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Feldmann MJ, Pincot DDA, Cole GS, Knapp SJ. Genetic gains underpinning a little-known strawberry Green Revolution. Nat Commun 2024; 15:2468. [PMID: 38504104 PMCID: PMC10951273 DOI: 10.1038/s41467-024-46421-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 02/26/2024] [Indexed: 03/21/2024] Open
Abstract
The annual production of strawberry has increased by one million tonnes in the US and 8.4 million tonnes worldwide since 1960. Here we show that the US expansion was driven by genetic gains from Green Revolution breeding and production advances that increased yields by 2,755%. Using a California population with a century-long breeding history and phenotypes of hybrids observed in coastal California environments, we estimate that breeding has increased fruit yields by 2,974-6,636%, counts by 1,454-3,940%, weights by 228-504%, and firmness by 239-769%. Using genomic prediction approaches, we pinpoint the origin of the Green Revolution to the early 1950s and uncover significant increases in additive genetic variation caused by transgressive segregation and phenotypic diversification. Lastly, we show that the most consequential Green Revolution breeding breakthrough was the introduction of photoperiod-insensitive, PERPETUAL FLOWERING hybrids in the 1970s that doubled yields and drove the dramatic expansion of strawberry production in California.
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Affiliation(s)
- Mitchell J Feldmann
- Department of Plant Sciences, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Dominique D A Pincot
- Department of Plant Sciences, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA.
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2
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Feldmann MJ, Pincot DDA, Vachev MV, Famula RA, Cole GS, Knapp SJ. Accelerating genetic gains for quantitative resistance to verticillium wilt through predictive breeding in strawberry. Plant Genome 2024; 17:e20405. [PMID: 37961831 DOI: 10.1002/tpg2.20405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 10/12/2023] [Indexed: 11/15/2023]
Abstract
Verticillium wilt (VW), a devastating vascular wilt disease of strawberry (Fragaria × $\times$ ananassa), has caused economic losses for nearly a century. This disease is caused by the soil-borne pathogen Verticillium dahliae, which occurs nearly worldwide and causes disease in numerous agriculturally important plants. The development of VW-resistant cultivars is critically important for the sustainability of strawberry production. We previously showed that a preponderance of the genetic resources (asexually propagated hybrid individuals) preserved in public germplasm collections were moderately to highly susceptible and that genetic gains for increased resistance to VW have been negligible over the last 60 years. To more fully understand the challenges associated with breeding for increased quantitative resistance to this pathogen, we developed and phenotyped a training population of hybrids (n = 564 $n = 564$ ) among elite parents with a wide range of resistance phenotypes. When these data were combined with training data from a population of elite and exotic hybrids (n = 386 $n = 386$ ), genomic prediction accuracies of 0.47-0.48 were achieved and were predicted to explain 70%-75% of the additive genetic variance for resistance. We concluded that breeding values for resistance to VW can be predicted with sufficient accuracy for effective genomic selection with routine updating of training populations.
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Affiliation(s)
- Mitchell J Feldmann
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Dominique D A Pincot
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Mishi V Vachev
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Randi A Famula
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California Davis, Davis, California, USA
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3
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Knapp SJ, Cole GS, Pincot DDA, Dilla-Ermita CJ, Bjornson M, Famula RA, Gordon TR, Harshman JM, Henry PM, Feldmann MJ. Transgressive segregation, hopeful monsters, and phenotypic selection drove rapid genetic gains and breakthroughs in predictive breeding for quantitative resistance to Macrophomina in strawberry. Hortic Res 2024; 11:uhad289. [PMID: 38487295 PMCID: PMC10939388 DOI: 10.1093/hr/uhad289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 12/17/2023] [Indexed: 03/17/2024]
Abstract
Two decades have passed since the strawberry (Fragaria x ananassa) disease caused by Macrophomina phaseolina, a necrotrophic soilborne fungal pathogen, began surfacing in California, Florida, and elsewhere. This disease has since become one of the most common causes of plant death and yield losses in strawberry. The Macrophomina problem emerged and expanded in the wake of the global phase-out of soil fumigation with methyl bromide and appears to have been aggravated by an increase in climate change-associated abiotic stresses. Here we show that sources of resistance to this pathogen are rare in gene banks and that the favorable alleles they carry are phenotypically unobvious. The latter were exposed by transgressive segregation and selection in populations phenotyped for resistance to Macrophomina under heat and drought stress. The genetic gains were immediate and dramatic. The frequency of highly resistant individuals increased from 1% in selection cycle 0 to 74% in selection cycle 2. Using GWAS and survival analysis, we found that phenotypic selection had increased the frequencies of favorable alleles among 10 loci associated with resistance and that favorable alleles had to be accumulated among four or more of these loci for an individual to acquire resistance. An unexpectedly straightforward solution to the Macrophomina disease resistance breeding problem emerged from our studies, which showed that highly resistant cultivars can be developed by genomic selection per se or marker-assisted stacking of favorable alleles among a comparatively small number of large-effect loci.
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Affiliation(s)
- Steven J Knapp
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Dominique D A Pincot
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Christine Jade Dilla-Ermita
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
- Crop Improvement and Protection Research, USDA-ARS, 1636 E. Alisal Street, CA 93905, USA
| | - Marta Bjornson
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Randi A Famula
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Thomas R Gordon
- Department of Plant Pathology, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Julia M Harshman
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Peter M Henry
- Crop Improvement and Protection Research, USDA-ARS, 1636 E. Alisal Street, CA 93905, USA
| | - Mitchell J Feldmann
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
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4
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Hardigan MA, Feldmann MJ, Carling J, Zhu A, Kilian A, Famula RA, Cole GS, Knapp SJ. A medium-density genotyping platform for cultivated strawberry using DArTag technology. Plant Genome 2023; 16:e20399. [PMID: 37940627 DOI: 10.1002/tpg2.20399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 09/22/2023] [Indexed: 11/10/2023]
Abstract
Genomic prediction in breeding populations containing hundreds to thousands of parents and seedlings is prohibitively expensive with current high-density genetic marker platforms designed for strawberry. We developed mid-density panels of molecular inversion probes (MIPs) to be deployed with the "DArTag" marker platform to provide a low-cost, high-throughput genotyping solution for strawberry genomic prediction. In total, 7742 target single nucleotide polymorphism (SNP) regions were used to generate MIP assays that were tested with a screening panel of 376 octoploid Fragaria accessions. We evaluated the performance of DArTag assays based on genotype segregation, amplicon coverage, and their ability to produce subgenome-specific amplicon alignments to the FaRR1 assembly and subsequent alignment-based variant calls with strong concordance to DArT's alignment-free, count-based genotype reports. We used a combination of marker performance metrics and physical distribution in the FaRR1 assembly to select 3K and 5K production panels for genotyping of large strawberry populations. We show that the 3K and 5K DArTag panels are able to target and amplify homologous alleles within subgenomic sequences with low-amplification bias between reference and alternate alleles, supporting accurate genotype calling while producing marker genotypes that can be treated as functionally diploid for quantitative genetic analysis. The 3K and 5K target SNPs show high levels of polymorphism in diverse F. × ananassa germplasm and UC Davis cultivars, with mean pairwise diversity (π) estimates of 0.40 and 0.32 and mean heterozygous genotype frequencies of 0.35 and 0.33, respectively.
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Affiliation(s)
- Michael A Hardigan
- USDA-ARS, Horticultural Crops Production and Genetic Improvement Research Unit, Corvallis, Oregon, USA
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Mitchell J Feldmann
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Jason Carling
- Diversity Arrays Technology, University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Anyu Zhu
- Diversity Arrays Technology, University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Andrzej Kilian
- Diversity Arrays Technology, University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Randi A Famula
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California Davis, Davis, California, USA
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5
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Jacobs M, Thompson S, Platts AE, Body MJA, Kelsey A, Saad A, Abeli P, Teresi SJ, Schilmiller A, Beaudry R, Feldmann MJ, Knapp SJ, Song GQ, Miles T, Edger PP. Uncovering genetic and metabolite markers associated with resistance against anthracnose fruit rot in northern highbush blueberry. Hortic Res 2023; 10:uhad169. [PMID: 38025975 PMCID: PMC10660357 DOI: 10.1093/hr/uhad169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 08/29/2023] [Indexed: 12/01/2023]
Abstract
Anthracnose fruit rot (AFR), caused by the fungal pathogen Colletotrichum fioriniae, is among the most destructive and widespread fruit disease of blueberry, impacting both yield and overall fruit quality. Blueberry cultivars have highly variable resistance against AFR. To date, this pathogen is largely controlled by applying various fungicides; thus, a more cost-effective and environmentally conscious solution for AFR is needed. Here we report three quantitative trait loci associated with AFR resistance in northern highbush blueberry (Vaccinium corymbosum). Candidate genes within these genomic regions are associated with the biosynthesis of flavonoids (e.g. anthocyanins) and resistance against pathogens. Furthermore, we examined gene expression changes in fruits following inoculation with Colletotrichum in a resistant cultivar, which revealed an enrichment of significantly differentially expressed genes associated with certain specialized metabolic pathways (e.g. flavonol biosynthesis) and pathogen resistance. Using non-targeted metabolite profiling, we identified a flavonol glycoside with properties consistent with a quercetin rhamnoside as a compound exhibiting significant abundance differences among the most resistant and susceptible individuals from the genetic mapping population. Further analysis revealed that this compound exhibits significant abundance differences among the most resistant and susceptible individuals when analyzed as two groups. However, individuals within each group displayed considerable overlapping variation in this compound, suggesting that its abundance may only be partially associated with resistance against C. fioriniae. These findings should serve as a powerful resource that will enable breeding programs to more easily develop new cultivars with superior resistance to AFR and as the basis of future research studies.
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Affiliation(s)
- MacKenzie Jacobs
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
- Molecular Plant Science Program, Michigan State University, East Lansing, MI 48824, USA
| | - Samantha Thompson
- Molecular Plant Science Program, Michigan State University, East Lansing, MI 48824, USA
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA
| | - Adrian E Platts
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
| | - Melanie J A Body
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
| | - Alexys Kelsey
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
| | - Amanda Saad
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
| | - Patrick Abeli
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
- Department of Horticulture and Natural Resources, Kansas State University, Olathe, KS 66061, USA
| | - Scott J Teresi
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
- Genetics and Genome Sciences Program, Michigan State University, East Lansing, MI 48824, USA
| | - Anthony Schilmiller
- Mass Spectrometry & Metabolomics Core, Michigan State University, East Lansing, MI 48824, USA
| | - Randolph Beaudry
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
| | - Mitchell J Feldmann
- Department of Plant Sciences, University of California, Davis, CA 95616, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, CA 95616, USA
| | - Guo-qing Song
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
| | - Timothy Miles
- Molecular Plant Science Program, Michigan State University, East Lansing, MI 48824, USA
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA
- Genetics and Genome Sciences Program, Michigan State University, East Lansing, MI 48824, USA
| | - Patrick P Edger
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
- Molecular Plant Science Program, Michigan State University, East Lansing, MI 48824, USA
- Genetics and Genome Sciences Program, Michigan State University, East Lansing, MI 48824, USA
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Jiménez NP, Feldmann MJ, Famula RA, Pincot DDA, Bjornson M, Cole GS, Knapp SJ. Harnessing underutilized gene bank diversity and genomic prediction of cross usefulness to enhance resistance to Phytophthora cactorum in strawberry. Plant Genome 2023; 16:e20275. [PMID: 36480594 DOI: 10.1002/tpg2.20275] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/19/2022] [Indexed: 05/10/2023]
Abstract
The development of strawberry (Fragaria × ananassa Duchesne ex Rozier) cultivars resistant to Phytophthora crown rot (PhCR), a devastating disease caused by the soil-borne pathogen Phytophthora cactorum (Lebert & Cohn) J. Schröt., has been challenging partly because the resistance phenotypes are quantitative and only moderately heritable. To develop deeper insights into the genetics of resistance and build the foundation for applying genomic selection, a genetically diverse training population was screened for resistance to California isolates of the pathogen. Here we show that genetic gains in breeding for resistance to PhCR have been negligible (3% of the cultivars tested were highly resistant and none surpassed early 20th century cultivars). Narrow-sense genomic heritability for PhCR resistance ranged from 0.41 to 0.75 among training population individuals. Using multivariate genome-wide association studies (GWAS), we identified a large-effect locus (predicted to be RPc2) that explained 43.6-51.6% of the genetic variance, was necessary but not sufficient for resistance, and was associated with calcium channel and other candidate genes with known plant defense functions. The addition of underutilized gene bank resources to our training population doubled additive genetic variance, increased the accuracy of genomic selection, and enabled the discovery of individuals carrying favorable alleles that are either rare or not present in modern cultivars. The incorporation of an RPc2-associated single-nucleotide polymorphism (SNP) as a fixed effect increased genomic prediction accuracy from 0.40 to 0.55. Finally, we show that parent selection using genomic-estimated breeding values, genetic variances, and cross usefulness holds promise for enhancing resistance to PhCR in strawberry.
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Affiliation(s)
- Nicolás P Jiménez
- Dep. of Plant Sciences, Univ. of California, One Shields Ave, Davis, CA, 95616, USA
| | - Mitchell J Feldmann
- Dep. of Plant Sciences, Univ. of California, One Shields Ave, Davis, CA, 95616, USA
| | - Randi A Famula
- Dep. of Plant Sciences, Univ. of California, One Shields Ave, Davis, CA, 95616, USA
| | - Dominique D A Pincot
- Dep. of Plant Sciences, Univ. of California, One Shields Ave, Davis, CA, 95616, USA
| | - Marta Bjornson
- Dep. of Plant Sciences, Univ. of California, One Shields Ave, Davis, CA, 95616, USA
| | - Glenn S Cole
- Dep. of Plant Sciences, Univ. of California, One Shields Ave, Davis, CA, 95616, USA
| | - Steven J Knapp
- Dep. of Plant Sciences, Univ. of California, One Shields Ave, Davis, CA, 95616, USA
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7
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Fan Z, Tieman DM, Knapp SJ, Zerbe P, Famula R, Barbey CR, Folta KM, Amadeu RR, Lee M, Oh Y, Lee S, Whitaker VM. A multi-omics framework reveals strawberry flavor genes and their regulatory elements. New Phytol 2022; 236:1089-1107. [PMID: 35916073 PMCID: PMC9805237 DOI: 10.1111/nph.18416] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
Flavor is essential to consumer preference of foods and is an increasing focus of plant breeding programs. In fruit crops, identifying genes underlying volatile organic compounds has great promise to accelerate flavor improvement, but polyploidy and heterozygosity in many species have slowed progress. Here we use octoploid cultivated strawberry to demonstrate how genomic heterozygosity, transcriptomic intricacy and fruit metabolomic diversity can be treated as strengths and leveraged to uncover fruit flavor genes and their regulatory elements. Multi-omics datasets were generated including an expression quantitative trait loci map with 196 diverse breeding lines, haplotype-phased genomes of a highly-flavored breeding selection, a genome-wide structural variant map using five haplotypes, and volatile genome-wide association study (GWAS) with > 300 individuals. Overlaying regulatory elements, structural variants and GWAS-linked allele-specific expression of numerous genes to variation in volatile compounds important to flavor. In one example, the functional role of anthranilate synthase alpha subunit 1 in methyl anthranilate biosynthesis was supported via fruit transient gene expression assays. These results demonstrate a framework for flavor gene discovery in fruit crops and a pathway to molecular breeding of cultivars with complex and desirable flavor.
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Affiliation(s)
- Zhen Fan
- Horticultural Sciences DepartmentUniversity of Florida, IFAS Gulf Coast Research and Education CenterWimaumaFL33597USA
| | - Denise M. Tieman
- Horticultural Sciences DepartmentUniversity of FloridaGainesvilleFL32611USA
| | - Steven J. Knapp
- Department of Plant SciencesUniversity of CaliforniaDavisDavisCA95616USA
| | - Philipp Zerbe
- Department of Plant BiologyUniversity of California DavisDavisCA95616USA
| | - Randi Famula
- Department of Plant SciencesUniversity of CaliforniaDavisDavisCA95616USA
| | - Christopher R. Barbey
- Horticultural Sciences DepartmentUniversity of Florida, IFAS Gulf Coast Research and Education CenterWimaumaFL33597USA
| | - Kevin M. Folta
- Horticultural Sciences DepartmentUniversity of FloridaGainesvilleFL32611USA
| | - Rodrigo R. Amadeu
- Horticultural Sciences DepartmentUniversity of FloridaGainesvilleFL32611USA
| | - Manbo Lee
- Horticultural Sciences DepartmentUniversity of Florida, IFAS Gulf Coast Research and Education CenterWimaumaFL33597USA
| | - Youngjae Oh
- Horticultural Sciences DepartmentUniversity of Florida, IFAS Gulf Coast Research and Education CenterWimaumaFL33597USA
| | - Seonghee Lee
- Horticultural Sciences DepartmentUniversity of Florida, IFAS Gulf Coast Research and Education CenterWimaumaFL33597USA
| | - Vance M. Whitaker
- Horticultural Sciences DepartmentUniversity of Florida, IFAS Gulf Coast Research and Education CenterWimaumaFL33597USA
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Pincot DDA, Feldmann MJ, Hardigan MA, Vachev MV, Henry PM, Gordon TR, Bjornson M, Rodriguez A, Cobo N, Famula RA, Cole GS, Coaker GL, Knapp SJ. Novel Fusarium wilt resistance genes uncovered in natural and cultivated strawberry populations are found on three non-homoeologous chromosomes. Theor Appl Genet 2022; 135:2121-2145. [PMID: 35583656 PMCID: PMC9205853 DOI: 10.1007/s00122-022-04102-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/11/2022] [Indexed: 05/05/2023]
Abstract
Several Fusarium wilt resistance genes were discovered, genetically and physically mapped, and rapidly deployed via marker-assisted selection to develop cultivars resistant to Fusarium oxysporum f. sp. fragariae, a devastating soil-borne pathogen of strawberry. Fusarium wilt, a soilborne disease caused by Fusarium oxysporum f. sp. fragariae, poses a significant threat to strawberry (Fragaria [Formula: see text] ananassa) production in many parts of the world. This pathogen causes wilting, collapse, and death in susceptible genotypes. We previously identified a dominant gene (FW1) on chromosome 2B that confers resistance to race 1 of the pathogen, and hypothesized that gene-for-gene resistance to Fusarium wilt was widespread in strawberry. To explore this, a genetically diverse collection of heirloom and modern cultivars and octoploid ecotypes were screened for resistance to Fusarium wilt races 1 and 2. Here, we show that resistance to both races is widespread in natural and domesticated populations and that resistance to race 1 is conferred by partially to completely dominant alleles among loci (FW1, FW2, FW3, FW4, and FW5) found on three non-homoeologous chromosomes (1A, 2B, and 6B). The underlying genes have not yet been cloned and functionally characterized; however, plausible candidates were identified that encode pattern recognition receptors or other proteins known to confer gene-for-gene resistance in plants. High-throughput genotyping assays for SNPs in linkage disequilibrium with FW1-FW5 were developed to facilitate marker-assisted selection and accelerate the development of race 1 resistant cultivars. This study laid the foundation for identifying the genes encoded by FW1-FW5, in addition to exploring the genetics of resistance to race 2 and other races of the pathogen, as a precaution to averting a Fusarium wilt pandemic.
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Affiliation(s)
- Dominique D. A. Pincot
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616 USA
| | - Mitchell J. Feldmann
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616 USA
| | - Michael A. Hardigan
- Horticultural Crops Research Unit, United States Department of Agriculture, Agricultural Research Service, Corvallis, OR 97331 USA
| | - Mishi V. Vachev
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616 USA
| | - Peter M. Henry
- United States Department of Agriculture Agricultural Research Service, 1636 East Alisal Street, Salinas, CA 93905 USA
| | - Thomas R. Gordon
- Department of Plant Pathology, One Shields Avenue, University of California, Davis, CA 95616 USA
| | - Marta Bjornson
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616 USA
| | - Alan Rodriguez
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616 USA
| | - Nicolas Cobo
- Departamento de Producción, Agropecuaria Universidad de La Frontera, Temuco, Chile
| | - Randi A. Famula
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616 USA
| | - Glenn S. Cole
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616 USA
| | - Gitta L. Coaker
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616 USA
| | - Steven J. Knapp
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, CA 95616 USA
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Feldmann MJ, Piepho HP, Knapp SJ. Average semivariance directly yields accurate estimates of the genomic variance in complex trait analyses. G3 Genes|Genomes|Genetics 2022; 12:6571389. [PMID: 35442424 PMCID: PMC9157152 DOI: 10.1093/g3journal/jkac080] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 03/17/2022] [Indexed: 11/23/2022]
Abstract
Many important traits in plants, animals, and microbes are polygenic and challenging to improve through traditional marker-assisted selection. Genomic prediction addresses this by incorporating all genetic data in a mixed model framework. The primary method for predicting breeding values is genomic best linear unbiased prediction, which uses the realized genomic relationship or kinship matrix (K) to connect genotype to phenotype. Genomic relationship matrices share information among entries to estimate the observed entries’ genetic values and predict unobserved entries’ genetic values. One of the main parameters of such models is genomic variance (σg2), or the variance of a trait associated with a genome-wide sample of DNA polymorphisms, and genomic heritability (hg2); however, the seminal papers introducing different forms of K often do not discuss their effects on the model estimated variance components despite their importance in genetic research and breeding. Here, we discuss the effect of several standard methods for calculating the genomic relationship matrix on estimates of σg2 and hg2. With current approaches, we found that the genomic variance tends to be either overestimated or underestimated depending on the scaling and centering applied to the marker matrix (Z), the value of the average diagonal element of K, and the assortment of alleles and heterozygosity (H) in the observed population. Using the average semivariance, we propose a new matrix, KASV, that directly yields accurate estimates of σg2 and hg2 in the observed population and produces best linear unbiased predictors equivalent to routine methods in plants and animals.
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Affiliation(s)
- Mitchell J Feldmann
- Department of Plant Sciences, University of California , Davis, CA 95616, USA
| | - Hans-Peter Piepho
- Biostatistics Unit, Institute of Crop Science, University of Hohenheim , 70593 Stuttgart, Germany
| | - Steven J Knapp
- Department of Plant Sciences, University of California , Davis, CA 95616, USA
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10
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Petrasch S, Mesquida-Pesci SD, Pincot DDA, Feldmann MJ, López CM, Famula R, Hardigan MA, Cole GS, Knapp SJ, Blanco-Ulate B. Genomic prediction of strawberry resistance to postharvest fruit decay caused by the fungal pathogen Botrytis cinerea. G3 (Bethesda) 2022; 12:6427547. [PMID: 34791166 PMCID: PMC8728004 DOI: 10.1093/g3journal/jkab378] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 10/08/2021] [Indexed: 12/18/2022]
Abstract
Gray mold, a disease of strawberry (Fragaria × ananassa) caused by the ubiquitous necrotroph Botrytis cinerea, renders fruit unmarketable and causes economic losses in the postharvest supply chain. To explore the feasibility of selecting for increased resistance to gray mold, we undertook genetic and genomic prediction studies in strawberry populations segregating for fruit quality and shelf life traits hypothesized to pleiotropically affect susceptibility. As predicted, resistance to gray mold was heritable but quantitative and genetically complex. While every individual was susceptible, the speed of symptom progression and severity differed. Narrow-sense heritability ranged from 0.38 to 0.71 for lesion diameter (LD) and 0.39 to 0.44 for speed of emergence of external mycelium (EM). Even though significant additive genetic variation was observed for LD and EM, the phenotypic ranges were comparatively narrow and genome-wide analyses did not identify any large-effect loci. Genomic selection (GS) accuracy ranged from 0.28 to 0.59 for LD and 0.37 to 0.47 for EM. Additive genetic correlations between fruit quality and gray mold resistance traits were consistent with prevailing hypotheses: LD decreased as titratable acidity increased, whereas EM increased as soluble solid content decreased and firmness increased. We concluded that phenotypic and GS could be effective for reducing LD and increasing EM, especially in long shelf life populations, but that a significant fraction of the genetic variation for resistance to gray mold was caused by the pleiotropic effects of fruit quality traits that differ among market and shelf life classes.
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Affiliation(s)
- Stefan Petrasch
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | | | - Dominique D A Pincot
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Mitchell J Feldmann
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Cindy M López
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Randi Famula
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Michael A Hardigan
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Barbara Blanco-Ulate
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
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11
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Bird KA, Hardigan MA, Ragsdale AP, Knapp SJ, VanBuren R, Edger PP. Diversification, spread, and admixture of octoploid strawberry in the Western Hemisphere. Am J Bot 2021; 108:2269-2281. [PMID: 34636416 PMCID: PMC9299191 DOI: 10.1002/ajb2.1776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 08/13/2021] [Accepted: 08/18/2021] [Indexed: 05/11/2023]
Abstract
PREMISE Polyploid species often have complex evolutionary histories that have, until recently, been intractable due to limitations of genomic resources. While recent work has further uncovered the evolutionary history of the octoploid strawberry (Fragaria L.), there are still open questions. Much is unknown about the evolutionary relationship of the wild octoploid species, Fragaria virginiana and Fragaria chiloensis, and gene flow within and among species after the formation of the octoploid genome. METHODS We leveraged a collection of wild octoploid ecotypes of strawberry representing the recognized subspecies and ranging from Alaska to southern Chile, and a high-density SNP array to investigate wild octoploid strawberry evolution. Evolutionary relationships were interrogated with phylogenetic analysis and genetic clustering algorithms. Additionally, admixture among and within species is assessed with model-based and tree-based approaches. RESULTS Phylogenetic analysis revealed that the two octoploid strawberry species are monophyletic sister lineages. The genetic clustering results show substructure between North and South American F. chiloensis populations. Additionally, model-based and tree-based methods support gene flow within and among the two octoploid species, including newly identified admixture in the Hawaiian F. chiloensis subsp. sandwicensis population. CONCLUSIONS F. virginiana and F. chiloensis are supported as monophyletic and sister lineages. All but one of the subspecies show extensive paraphyly. Furthermore, phylogenetic relationships among F. chiloensis populations supports a single population range expansion southward from North America. The inter- and intraspecific relationships of octoploid strawberry are complex and suggest substantial gene flow between sympatric populations among and within species.
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Affiliation(s)
- Kevin A. Bird
- Department of HorticultureMichigan State UniversityEast LansingMichigan48823USA
- Ecology, Evolution and Behavior ProgramMichigan State UniversityEast LansingMichigan48823USA
| | | | - Aaron P. Ragsdale
- National Laboratory of Genomics for Biodiversity (LANGEBIO)Unit of Advanced Genomics, CINVESTAVIrapuatoMexico
| | - Steven J. Knapp
- Department of Plant SciencesUniversity of CaliforniaDavisCalifornia95616USA
| | - Robert VanBuren
- Department of HorticultureMichigan State UniversityEast LansingMichigan48823USA
- Plant Resilience InstituteMichigan State UniversityEast LansingMichigan48824USA
| | - Patrick P. Edger
- Department of HorticultureMichigan State UniversityEast LansingMichigan48823USA
- Ecology, Evolution and Behavior ProgramMichigan State UniversityEast LansingMichigan48823USA
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12
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Pincot DDA, Ledda M, Feldmann MJ, Hardigan MA, Poorten TJ, Runcie DE, Heffelfinger C, Dellaporta SL, Cole GS, Knapp SJ. Corrigendum to: "Social network analysis of the genealogy of strawberry: retracing the wild roots of heirloom and modern cultivars". G3 (Bethesda) 2021; 11:6358300. [PMID: 34568936 PMCID: PMC8473969 DOI: 10.1093/g3journal/jkab257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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13
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Feldmann MJ, Piepho HP, Bridges WC, Knapp SJ. Average semivariance yields accurate estimates of the fraction of marker-associated genetic variance and heritability in complex trait analyses. PLoS Genet 2021; 17:e1009762. [PMID: 34437540 PMCID: PMC8425577 DOI: 10.1371/journal.pgen.1009762] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 09/08/2021] [Accepted: 08/09/2021] [Indexed: 12/15/2022] Open
Abstract
The development of genome-informed methods for identifying quantitative trait loci (QTL) and studying the genetic basis of quantitative variation in natural and experimental populations has been driven by advances in high-throughput genotyping. For many complex traits, the underlying genetic variation is caused by the segregation of one or more ‘large-effect’ loci, in addition to an unknown number of loci with effects below the threshold of statistical detection. The large-effect loci segregating in populations are often necessary but not sufficient for predicting quantitative phenotypes. They are, nevertheless, important enough to warrant deeper study and direct modelling in genomic prediction problems. We explored the accuracy of statistical methods for estimating the fraction of marker-associated genetic variance (p) and heritability ( HM2) for large-effect loci underlying complex phenotypes. We found that commonly used statistical methods overestimate p and HM2. The source of the upward bias was traced to inequalities between the expected values of variance components in the numerators and denominators of these parameters. Algebraic solutions for bias-correcting estimates of p and HM2 were found that only depend on the degrees of freedom and are constant for a given study design. We discovered that average semivariance methods, which have heretofore not been used in complex trait analyses, yielded unbiased estimates of p and HM2, in addition to best linear unbiased predictors of the additive and dominance effects of the underlying loci. The cryptic bias problem described here is unrelated to selection bias, although both cause the overestimation of p and HM2. The solutions we described are predicted to more accurately describe the contributions of large-effect loci to the genetic variation underlying complex traits of medical, biological, and agricultural importance. The contributions of individual genes to the phenotypic variation observed for genetically complex traits has been an ongoing and important challenge in biology, medicine, and agriculture. While many genes have statistically undetectable effects, those with large effects often warrant in-depth study and can be important predictors of complex phenotypes such as disease risk in humans or disease resistance in domesticated plants and animals. The genes identified through associations with genetic markers in complex trait analyses typically account for a fraction of the heritable variation, a genetic parameter we called ‘marker heritability’. We discovered that textbook statistical methods systematically overestimate marker heritability and thus overestimate the contributions of specific genes to the phenotypic variation observed for complex traits in natural and experimental populations. We describe the source of the upward bias, validate our findings through computer simulation, describe methods for bias-correcting estimates of marker heritability, and illustrate their application through empirical examples. The statistical methods we describe supply investigators with more accurate estimates of the contributions of specific genes or networks of interacting genes to the heritable variation observed in complex trait studies.
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Affiliation(s)
- Mitchell J. Feldmann
- Department of Plant Sciences, University of California, Davis, California, United States of America
| | - Hans-Peter Piepho
- Biostatistics Unit, Institute of Crop Science, University of Hohenheim, Stuttgart, Germany
| | - William C. Bridges
- Department of Mathematical Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Steven J. Knapp
- Department of Plant Sciences, University of California, Davis, California, United States of America
- * E-mail:
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14
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Hardigan MA, Lorant A, Pincot DDA, Feldmann MJ, Famula RA, Acharya CB, Lee S, Verma S, Whitaker VM, Bassil N, Zurn J, Cole GS, Bird K, Edger PP, Knapp SJ. Unraveling the Complex Hybrid Ancestry and Domestication History of Cultivated Strawberry. Mol Biol Evol 2021; 38:2285-2305. [PMID: 33507311 PMCID: PMC8136507 DOI: 10.1093/molbev/msab024] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cultivated strawberry (Fragaria × ananassa) is one of our youngest domesticates, originating in early eighteenth-century Europe from spontaneous hybrids between wild allo-octoploid species (Fragaria chiloensis and Fragaria virginiana). The improvement of horticultural traits by 300 years of breeding has enabled the global expansion of strawberry production. Here, we describe the genomic history of strawberry domestication from the earliest hybrids to modern cultivars. We observed a significant increase in heterozygosity among interspecific hybrids and a decrease in heterozygosity among domesticated descendants of those hybrids. Selective sweeps were found across the genome in early and modern phases of domestication—59–76% of the selectively swept genes originated in the three less dominant ancestral subgenomes. Contrary to the tenet that genetic diversity is limited in cultivated strawberry, we found that the octoploid species harbor massive allelic diversity and that F. × ananassa harbors as much allelic diversity as either wild founder. We identified 41.8 M subgenome-specific DNA variants among resequenced wild and domesticated individuals. Strikingly, 98% of common alleles and 73% of total alleles were shared between wild and domesticated populations. Moreover, genome-wide estimates of nucleotide diversity were virtually identical in F. chiloensis,F. virginiana, and F. × ananassa (π = 0.0059–0.0060). We found, however, that nucleotide diversity and heterozygosity were significantly lower in modern F. × ananassa populations that have experienced significant genetic gains and have produced numerous agriculturally important cultivars.
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Affiliation(s)
- Michael A Hardigan
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Anne Lorant
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Dominique D A Pincot
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Mitchell J Feldmann
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Randi A Famula
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Charlotte B Acharya
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Seonghee Lee
- IFAS Gulf Coast Research and Education Center, Department of Horticulture, University of Florida, Wimauma, FL 33598, USA
| | - Sujeet Verma
- IFAS Gulf Coast Research and Education Center, Department of Horticulture, University of Florida, Wimauma, FL 33598, USA
| | - Vance M Whitaker
- IFAS Gulf Coast Research and Education Center, Department of Horticulture, University of Florida, Wimauma, FL 33598, USA
| | - Nahla Bassil
- USDA-ARS, National Clonal Germplasm Repository, Corvallis, OR 92182, USA
| | - Jason Zurn
- USDA-ARS, National Clonal Germplasm Repository, Corvallis, OR 92182, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Kevin Bird
- Department of Horticultural Science, Michigan State University, East Lansing, MI 48824, USA
| | - Patrick P Edger
- Department of Horticultural Science, Michigan State University, East Lansing, MI 48824, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
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15
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Alger EI, Platts AE, Deb SK, Luo X, Ou S, Cao Y, Hummer KE, Xiong Z, Knapp SJ, Liu Z, McKain MR, Edger PP. Chromosome-Scale Genome for a Red-Fruited, Perpetual Flowering and Runnerless Woodland Strawberry ( Fragaria vesca). Front Genet 2021; 12:671371. [PMID: 34335685 PMCID: PMC8323839 DOI: 10.3389/fgene.2021.671371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/31/2021] [Indexed: 12/04/2022] Open
Affiliation(s)
- Elizabeth I Alger
- Department of Horticulture, Michigan State University, East Lansing, MI, United States
| | - Adrian E Platts
- Department of Horticulture, Michigan State University, East Lansing, MI, United States
| | - Sontosh K Deb
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, United States.,Department of Forestry and Environmental Science, Shahjalal University of Science and Technology, Sylhet, Bangladesh
| | - Xi Luo
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, United States
| | - Shujun Ou
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, United States
| | - Yao Cao
- College of Life Science, Inner Mongolia University, Hohhot, China
| | - Kim E Hummer
- USDA ARS National Clonal Germplasm Repository, Corvallis, OR, United States
| | - Zhiyong Xiong
- College of Life Science, Inner Mongolia University, Hohhot, China
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Zhongchi Liu
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, United States
| | - Michael R McKain
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, United States
| | - Patrick P Edger
- Department of Horticulture, Michigan State University, East Lansing, MI, United States.,Genetics and Genome Sciences Program, Michigan State University, East Lansing, MI, United States
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16
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Pincot DDA, Ledda M, Feldmann MJ, Hardigan MA, Poorten TJ, Runcie DE, Heffelfinger C, Dellaporta SL, Cole GS, Knapp SJ. Social network analysis of the genealogy of strawberry: retracing the wild roots of heirloom and modern cultivars. G3 (Bethesda) 2021; 11:6117203. [PMID: 33772307 PMCID: PMC8022721 DOI: 10.1093/g3journal/jkab015] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/12/2020] [Indexed: 01/22/2023]
Abstract
The widely recounted story of the origin of cultivated strawberry (Fragaria × ananassa) oversimplifies the complex interspecific hybrid ancestry of the highly admixed populations from which heirloom and modern cultivars have emerged. To develop deeper insights into the three-century-long domestication history of strawberry, we reconstructed the genealogy as deeply as possible—pedigree records were assembled for 8,851 individuals, including 2,656 cultivars developed since 1775. The parents of individuals with unverified or missing pedigree records were accurately identified by applying an exclusion analysis to array-genotyped single-nucleotide polymorphisms. We identified 187 wild octoploid and 1,171 F. × ananassa founders in the genealogy, from the earliest hybrids to modern cultivars. The pedigree networks for cultivated strawberry are exceedingly complex labyrinths of ancestral interconnections formed by diverse hybrid ancestry, directional selection, migration, admixture, bottlenecks, overlapping generations, and recurrent hybridization with common ancestors that have unequally contributed allelic diversity to heirloom and modern cultivars. Fifteen to 333 ancestors were predicted to have transmitted 90% of the alleles found in country-, region-, and continent-specific populations. Using parent–offspring edges in the global pedigree network, we found that selection cycle lengths over the past 200 years of breeding have been extraordinarily long (16.0-16.9 years/generation), but decreased to a present-day range of 6.0-10.0 years/generation. Our analyses uncovered conspicuous differences in the ancestry and structure of North American and European populations, and shed light on forces that have shaped phenotypic diversity in F. × ananassa.
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Affiliation(s)
- Dominique D A Pincot
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Mirko Ledda
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Mitchell J Feldmann
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Michael A Hardigan
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Thomas J Poorten
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Daniel E Runcie
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Christopher Heffelfinger
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Stephen L Dellaporta
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
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17
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Henry PM, Pincot DD, Jenner BN, Borrero C, Aviles M, Nam M, Epstein L, Knapp SJ, Gordon TR. Horizontal chromosome transfer and independent evolution drive diversification in Fusarium oxysporum f. sp. fragariae. New Phytol 2021; 230:327-340. [PMID: 33616938 PMCID: PMC7986148 DOI: 10.1111/nph.17141] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 12/02/2020] [Indexed: 05/13/2023]
Abstract
The genes required for host-specific pathogenicity in Fusarium oxysporum can be acquired through horizontal chromosome transfer (HCT). However, it is unknown if HCT commonly contributes to the diversification of pathotypes. Using comparative genomics and pathogenicity phenotyping, we explored the role of HCT in the evolution of F. oxysporum f. sp. fragariae, the cause of Fusarium wilt of strawberry, with isolates from four continents. We observed two distinct syndromes: one included chlorosis ('yellows-fragariae') and the other did not ('wilt-fragariae'). All yellows-fragariae isolates carried a predicted pathogenicity chromosome, 'chrY-frag ', that was horizontally transferred at least four times. chrY-frag was associated with virulence on specific cultivars and encoded predicted effectors that were highly upregulated during infection. chrY-frag was not present in wilt-fragariae; isolates causing this syndrome evolved pathogenicity independently. All origins of F. oxysporum f. sp. fragariae occurred outside of the host's native range. Our data support the conclusion that HCT is widespread in F. oxysporum, but pathogenicity can also evolve independently. The absence of chrY-frag in wilt-fragariae suggests that multiple, distinct pathogenicity chromosomes can confer the same host specificity. The wild progenitors of cultivated strawberry (Fragaria × ananassa) did not co-evolve with this pathogen, yet we discovered several sources of genetic resistance.
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Affiliation(s)
- Peter M. Henry
- United States Department of AgricultureAgricultural Research Service1636 E. Alisal St.SalinasCA93905USA
| | - Dominique D.A. Pincot
- Department of Plant SciencesUniversity of CaliforniaOne Shields AvenueDavisCA95616USA
| | - Bradley N. Jenner
- Department of Plant PathologyUniversity of CaliforniaOne Shields AvenueDavisCA95616USA
| | - Celia Borrero
- Department of Ciencias AgroforestalesEscuela Técnica Superior de Ingeniería AgronómicaUniversidad de SevillaCtra. Utrera km 1Sevilla41013Spain
| | - Manuel Aviles
- Department of Ciencias AgroforestalesEscuela Técnica Superior de Ingeniería AgronómicaUniversidad de SevillaCtra. Utrera km 1Sevilla41013Spain
| | - Myeong‐Hyeon Nam
- Strawberry Research InstituteChungcheongnam‐do Agricultural Research & Extension ServicesNonsan32914Korea
| | - Lynn Epstein
- Department of Plant PathologyUniversity of CaliforniaOne Shields AvenueDavisCA95616USA
| | - Steven J. Knapp
- Department of Plant SciencesUniversity of CaliforniaOne Shields AvenueDavisCA95616USA
| | - Thomas R. Gordon
- Department of Plant PathologyUniversity of CaliforniaOne Shields AvenueDavisCA95616USA
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18
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Nelson JR, Verma S, Bassil NV, Finn CE, Hancock JF, Cole GS, Knapp SJ, Whitaker VM. Discovery of three loci increasing resistance to charcoal rot caused by Macrophomina phaseolina in octoploid strawberry. G3 (Bethesda) 2021; 11:jkab037. [PMID: 33565594 PMCID: PMC8022958 DOI: 10.1093/g3journal/jkab037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 01/25/2021] [Indexed: 11/12/2022]
Abstract
Charcoal rot caused by Macrophomina phaseolinais an increasing economic problem in annualized strawberry production systems around the world. Currently there are no effective postfumigation chemical controls for managing charcoal rot, and no information is available on the genetic architecture of resistance to M. phaseolina in strawberry (Fragaria ×ananassa). In this study, three multiparental discovery populations and two validation populations were inoculated at planting and evaluated for mortality in three consecutive growing seasons. Genome-wide SNP genotyping and pedigree-based analysis with FlexQTL™ software were performed. Two large-effect quantitative trait loci (QTL) increasing charcoal rot resistance were discovered and validated in cultivated germplasm. FaRMp1 was located on linkage group 2A in the interval 20.4to 24.9 cM, while FaRMp2 was located on linkage group 4B in the interval 41.1to 61.2 cM. Together these QTLs explained 27% and 17% of the phenotypic variance in two discovery populations consisting of elite breeding germplasm. For both QTLs, the resistant allele showed some evidence of partial dominance, but no significant interaction was detected between the two loci. As the dosage of resistant alleles increased from 0 to 4 across the two QTLs, mortality decreased regardless of the combination of alleles.A third locus, FaRMp3 on 4D, was discovered in FVC 11-58, a reconstituted F.×ananassa originating from diverse F. virginiana and F. chiloensis accessions. This locus accounted for 44% of phenotypic variation in four segregating crosses. These findings will form the basis for DNA-informed breeding for resistance to charcoal rot in cultivated strawberry.
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Affiliation(s)
- Jonathan R Nelson
- Department of Horticultural Science, University of Florida, IFAS Gulf Coast Research and Education Center, 14625 CR 672 Wimauma, FL 33598, USA
| | - Sujeet Verma
- Department of Horticultural Science, University of Florida, IFAS Gulf Coast Research and Education Center, 14625 CR 672 Wimauma, FL 33598, USA
| | - Nahla V Bassil
- USDA-ARS National Clonal Germplasm Repository, Corvallis, OR 97333, USA
| | - Chad E Finn
- USDA-ARS, HCRU, 3420 NW Orchard Avenue, Corvallis, OR 97330, USA (posthumous)
| | - James F Hancock
- Department of Horticulture, Michigan State University, East Lansing, MI 48824, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California, Davis, CA 95616, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, CA 95616, USA
| | - Vance M Whitaker
- Department of Horticultural Science, University of Florida, IFAS Gulf Coast Research and Education Center, 14625 CR 672 Wimauma, FL 33598, USA
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19
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Castillejo C, Waurich V, Wagner H, Ramos R, Oiza N, Muñoz P, Triviño JC, Caruana J, Liu Z, Cobo N, Hardigan MA, Knapp SJ, Vallarino JG, Osorio S, Martín-Pizarro C, Posé D, Toivainen T, Hytönen T, Oh Y, Barbey CR, Whitaker VM, Lee S, Olbricht K, Sánchez-Sevilla JF, Amaya I. Allelic Variation of MYB10 Is the Major Force Controlling Natural Variation in Skin and Flesh Color in Strawberry ( Fragaria spp.) Fruit. Plant Cell 2020; 32:3723-3749. [PMID: 33004617 PMCID: PMC7721342 DOI: 10.1105/tpc.20.00474] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/13/2020] [Accepted: 09/25/2020] [Indexed: 05/02/2023]
Abstract
The fruits of diploid and octoploid strawberry (Fragaria spp) show substantial natural variation in color due to distinct anthocyanin accumulation and distribution patterns. Anthocyanin biosynthesis is controlled by a clade of R2R3 MYB transcription factors, among which MYB10 is the main activator in strawberry fruit. Here, we show that mutations in MYB10 cause most of the variation in anthocyanin accumulation and distribution observed in diploid woodland strawberry (F. vesca) and octoploid cultivated strawberry (F ×ananassa). Using a mapping-by-sequencing approach, we identified a gypsy-transposon in MYB10 that truncates the protein and knocks out anthocyanin biosynthesis in a white-fruited F. vesca ecotype. Two additional loss-of-function mutations in MYB10 were identified among geographically diverse white-fruited F. vesca ecotypes. Genetic and transcriptomic analyses of octoploid Fragaria spp revealed that FaMYB10-2, one of three MYB10 homoeologs identified, regulates anthocyanin biosynthesis in developing fruit. Furthermore, independent mutations in MYB10-2 are the underlying cause of natural variation in fruit skin and flesh color in octoploid strawberry. We identified a CACTA-like transposon (FaEnSpm-2) insertion in the MYB10-2 promoter of red-fleshed accessions that was associated with enhanced expression. Our findings suggest that cis-regulatory elements in FaEnSpm-2 are responsible for enhanced MYB10-2 expression and anthocyanin biosynthesis in strawberry fruit flesh.
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Affiliation(s)
- Cristina Castillejo
- Laboratorio de Genómica y Biotecnología, Instituto Andaluz de Investigación y Formación Agraria y Pesquera (IFAPA) Centro de Málaga, 29140 Málaga, Spain
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
| | - Veronika Waurich
- Hansabred GmbH & Co. KG, 01108 Dresden, Germany
- Institut für Botanik, Technische Universität Dresden, 01062 Dresden, Germany
| | - Henning Wagner
- Hansabred GmbH & Co. KG, 01108 Dresden, Germany
- Institut für Botanik, Technische Universität Dresden, 01062 Dresden, Germany
| | - Rubén Ramos
- Laboratorio de Genómica y Biotecnología, Instituto Andaluz de Investigación y Formación Agraria y Pesquera (IFAPA) Centro de Málaga, 29140 Málaga, Spain
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
| | - Nicolás Oiza
- Laboratorio de Genómica y Biotecnología, Instituto Andaluz de Investigación y Formación Agraria y Pesquera (IFAPA) Centro de Málaga, 29140 Málaga, Spain
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
| | - Pilar Muñoz
- Laboratorio de Genómica y Biotecnología, Instituto Andaluz de Investigación y Formación Agraria y Pesquera (IFAPA) Centro de Málaga, 29140 Málaga, Spain
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
| | | | - Julie Caruana
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
| | - Zhongchi Liu
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
| | - Nicolás Cobo
- Department of Plant Sciences, University of California, Davis, California 95616
- Departamento de Producción Agropecuaria, Universidad de La Frontera, Temuco 01145, Chile
| | - Michael A Hardigan
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, California 95616
| | - José G Vallarino
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
- Departmento de Biología Molecular y Bioquímica, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM), Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Campus de Teatinos 29071, Málaga, Spain
| | - Sonia Osorio
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
- Departmento de Biología Molecular y Bioquímica, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM), Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Campus de Teatinos 29071, Málaga, Spain
| | - Carmen Martín-Pizarro
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
- Departmento de Biología Molecular y Bioquímica, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM), Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Campus de Teatinos 29071, Málaga, Spain
| | - David Posé
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
- Departmento de Biología Molecular y Bioquímica, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM), Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Campus de Teatinos 29071, Málaga, Spain
| | - Tuomas Toivainen
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki 00790, Finland
| | - Timo Hytönen
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki 00790, Finland
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki 00790, Finland
- National Institute of Agricultural Botany East Malling Research (NIAB EMR), Kent ME19 6BJ, United Kingdom
| | - Youngjae Oh
- Department of Horticultural Sciences, University of Florida, Institute of Food and Agricultural Sciences (IFAS) Gulf Coast Research and Education Center, Wimauma, Florida 33598
| | - Christopher R Barbey
- Department of Horticultural Sciences, University of Florida, Institute of Food and Agricultural Sciences (IFAS) Gulf Coast Research and Education Center, Wimauma, Florida 33598
| | - Vance M Whitaker
- Department of Horticultural Sciences, University of Florida, Institute of Food and Agricultural Sciences (IFAS) Gulf Coast Research and Education Center, Wimauma, Florida 33598
| | - Seonghee Lee
- Department of Horticultural Sciences, University of Florida, Institute of Food and Agricultural Sciences (IFAS) Gulf Coast Research and Education Center, Wimauma, Florida 33598
| | | | - José F Sánchez-Sevilla
- Laboratorio de Genómica y Biotecnología, Instituto Andaluz de Investigación y Formación Agraria y Pesquera (IFAPA) Centro de Málaga, 29140 Málaga, Spain
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
| | - Iraida Amaya
- Laboratorio de Genómica y Biotecnología, Instituto Andaluz de Investigación y Formación Agraria y Pesquera (IFAPA) Centro de Málaga, 29140 Málaga, Spain
- Unidad Asociada de I + D + i IFAPA-Consejo Superior de Investigaciones Científicas-Universidad de Málaga (IFAPA-IHSM) Biotecnología y Mejora en Fresa, Málaga 29071, Spain
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20
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Hon T, Mars K, Young G, Tsai YC, Karalius JW, Landolin JM, Maurer N, Kudrna D, Hardigan MA, Steiner CC, Knapp SJ, Ware D, Shapiro B, Peluso P, Rank DR. Highly accurate long-read HiFi sequencing data for five complex genomes. Sci Data 2020; 7:399. [PMID: 33203859 PMCID: PMC7673114 DOI: 10.1038/s41597-020-00743-4] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 10/27/2020] [Indexed: 02/06/2023] Open
Abstract
The PacBio® HiFi sequencing method yields highly accurate long-read sequencing datasets with read lengths averaging 10–25 kb and accuracies greater than 99.5%. These accurate long reads can be used to improve results for complex applications such as single nucleotide and structural variant detection, genome assembly, assembly of difficult polyploid or highly repetitive genomes, and assembly of metagenomes. Currently, there is a need for sample data sets to both evaluate the benefits of these long accurate reads as well as for development of bioinformatic tools including genome assemblers, variant callers, and haplotyping algorithms. We present deep coverage HiFi datasets for five complex samples including the two inbred model genomes Mus musculus and Zea mays, as well as two complex genomes, octoploid Fragaria × ananassa and the diploid anuran Rana muscosa. Additionally, we release sequence data from a mock metagenome community. The datasets reported here can be used without restriction to develop new algorithms and explore complex genome structure and evolution. Data were generated on the PacBio Sequel II System. Measurement(s) | DNA • genome • Metagenome | Technology Type(s) | DNA sequencing • PacBio Sequel System | Factor Type(s) | organism that had its genome sequenced | Sample Characteristic - Organism | Mus musculus • Rana muscosa • Fragaria x ananassa • Zea mays |
Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.12855527
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Affiliation(s)
- Ting Hon
- Pacific Biosciences of California Inc., 1305 O'Brien Dr., Menlo Park, CA, 94025, USA
| | - Kristin Mars
- Pacific Biosciences of California Inc., 1305 O'Brien Dr., Menlo Park, CA, 94025, USA
| | - Greg Young
- Pacific Biosciences of California Inc., 1305 O'Brien Dr., Menlo Park, CA, 94025, USA
| | - Yu-Chih Tsai
- Pacific Biosciences of California Inc., 1305 O'Brien Dr., Menlo Park, CA, 94025, USA
| | - Joseph W Karalius
- Pacific Biosciences of California Inc., 1305 O'Brien Dr., Menlo Park, CA, 94025, USA
| | - Jane M Landolin
- Ravel Biotechnology Inc., 953 Indiana St., San Francisco, CA, 94107, USA
| | - Nicholas Maurer
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, 95064, USA
| | - David Kudrna
- Arizona Genomics Institute and School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA
| | - Michael A Hardigan
- Department of Plant Sciences, University of California, Davis, One Shields Ave, Davis, CA, 95616-8571, USA
| | - Cynthia C Steiner
- Conservation Genetics, Beckman Center for Conservation Research, San Diego Zoo Global, 15600 San Pasqual Valley Road, Escondido, CA, 92027, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, One Shields Ave, Davis, CA, 95616-8571, USA
| | - Doreen Ware
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11724, USA.,USDA-ARS, Plant, Soil, and Nutrition Research Unit, Ithaca, NY, 14853, USA
| | - Beth Shapiro
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, 95064, USA.,Howard Hughes Medical Institute, University of California Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Paul Peluso
- Pacific Biosciences of California Inc., 1305 O'Brien Dr., Menlo Park, CA, 94025, USA
| | - David R Rank
- Pacific Biosciences of California Inc., 1305 O'Brien Dr., Menlo Park, CA, 94025, USA.
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21
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Pincot DDA, Hardigan MA, Cole GS, Famula RA, Henry PM, Gordon TR, Knapp SJ. Accuracy of genomic selection and long-term genetic gain for resistance to Verticillium wilt in strawberry. Plant Genome 2020; 13:e20054. [PMID: 33217217 DOI: 10.1002/tpg2.20054] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 07/03/2020] [Accepted: 07/21/2020] [Indexed: 05/17/2023]
Abstract
Verticillium wilt, a soil-borne disease caused by the fungal pathogen Verticillium dahliae, threatens strawberry (Fragaria × ananassa) production worldwide. The development of resistant cultivars has been a persistent challenge, in part because the genetics of resistance is complex. The heritability of resistance and genetic gains in breeding for resistance to this pathogen have not been well documented. To elucidate the genetics, assess long-term genetic gains, and estimate the accuracy of genomic selection for resistance to Verticillium wilt, we analyzed a genetically diverse population of elite and exotic germplasm accessions (n = 984), including 245 cultivars developed since 1854. We observed a full range of phenotypes, from highly susceptible to highly resistant: < 3% were classified as highly resistant, whereas > 50% were classified as moderately to highly susceptible. Broad-sense heritability estimates ranged from 0.70-0.76, whereas narrow-sense genomic heritability estimates ranged from 0.33-0.45. We found that genetic gains in breeding for resistance to Verticillium wilt have been negative over the last 165 years (mean resistance has decreased over time). We identified several highly resistant accessions that might harbor favorable alleles that are either rare or non-existent in modern populations. We did not observe the segregation of large-effect loci. The accuracy of genomic predictions ranged from 0.38-0.53 among years and whole-genome regression methods. We show that genomic selection has promise for increasing genetic gains and accelerating the development of resistant cultivars in strawberry by shortening selection cycles and enabling selection in early developmental stages without phenotyping.
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Affiliation(s)
- Dominique D A Pincot
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Michael A Hardigan
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Randi A Famula
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Peter M Henry
- United States Department of Agriculture, 1636 E. Alisal Street, Salinas, CA, 93905, USA
| | - Thomas R Gordon
- Department of Plant Pathology, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA
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22
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Feldmann MJ, Hardigan MA, Famula RA, López CM, Tabb A, Cole GS, Knapp SJ. Multi-dimensional machine learning approaches for fruit shape phenotyping in strawberry. Gigascience 2020; 9:giaa030. [PMID: 32352533 PMCID: PMC7191992 DOI: 10.1093/gigascience/giaa030] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 02/06/2020] [Accepted: 03/10/2020] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Shape is a critical element of the visual appeal of strawberry fruit and is influenced by both genetic and non-genetic determinants. Current fruit phenotyping approaches for external characteristics in strawberry often rely on the human eye to make categorical assessments. However, fruit shape is an inherently multi-dimensional, continuously variable trait and not adequately described by a single categorical or quantitative feature. Morphometric approaches enable the study of complex, multi-dimensional forms but are often abstract and difficult to interpret. In this study, we developed a mathematical approach for transforming fruit shape classifications from digital images onto an ordinal scale called the Principal Progression of k Clusters (PPKC). We use these human-recognizable shape categories to select quantitative features extracted from multiple morphometric analyses that are best fit for genetic dissection and analysis. RESULTS We transformed images of strawberry fruit into human-recognizable categories using unsupervised machine learning, discovered 4 principal shape categories, and inferred progression using PPKC. We extracted 68 quantitative features from digital images of strawberries using a suite of morphometric analyses and multivariate statistical approaches. These analyses defined informative feature sets that effectively captured quantitative differences between shape classes. Classification accuracy ranged from 68% to 99% for the newly created phenotypic variables for describing a shape. CONCLUSIONS Our results demonstrated that strawberry fruit shapes could be robustly quantified, accurately classified, and empirically ordered using image analyses, machine learning, and PPKC. We generated a dictionary of quantitative traits for studying and predicting shape classes and identifying genetic factors underlying phenotypic variability for fruit shape in strawberry. The methods and approaches that we applied in strawberry should apply to other fruits, vegetables, and specialty crops.
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Affiliation(s)
- Mitchell J Feldmann
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - Michael A Hardigan
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - Randi A Famula
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - Cindy M López
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - Amy Tabb
- USDA-ARS-AFRS, 2217 Wiltshire Rd, Kearneysville, WV 25430, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
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23
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Whitaker VM, Knapp SJ, Hardigan MA, Edger PP, Slovin JP, Bassil NV, Hytönen T, Mackenzie KK, Lee S, Jung S, Main D, Barbey CR, Verma S. A roadmap for research in octoploid strawberry. Hortic Res 2020; 7:33. [PMID: 32194969 PMCID: PMC7072068 DOI: 10.1038/s41438-020-0252-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 01/26/2020] [Indexed: 05/02/2023]
Abstract
The cultivated strawberry (Fragaria × ananassa) is an allo-octoploid species, originating nearly 300 years ago from wild progenitors from the Americas. Since that time the strawberry has become the most widely cultivated fruit crop in the world, universally appealing due to its sensory qualities and health benefits. The recent publication of the first high-quality chromosome-scale octoploid strawberry genome (cv. Camarosa) is enabling rapid advances in genetics, stimulating scientific debate and provoking new research questions. In this forward-looking review we propose avenues of research toward new biological insights and applications to agriculture. Among these are the origins of the genome, characterization of genetic variants, and big data approaches to breeding. Key areas of research in molecular biology will include the control of flowering, fruit development, fruit quality, and plant-pathogen interactions. In order to realize this potential as a global community, investments in genome resources must be continually augmented.
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Affiliation(s)
- Vance M Whitaker
- 1University of Florida, Institute of Food and Agricultural Sciences, Gulf Coast Research and Education Center, Wimauma, Florida 33598 USA
| | - Steven J Knapp
- 2Department of Plant Sciences, University of California, Davis, CA 95616 USA
| | - Michael A Hardigan
- 2Department of Plant Sciences, University of California, Davis, CA 95616 USA
| | - Patrick P Edger
- 3Department of Horticulture, Michigan State University, East Lansing, MI 48824 USA
| | - Janet P Slovin
- USDA-ARS Genetic Improvement of Fruits and Vegetables Laboratory, Beltsville, MA 20705 USA
| | - Nahla V Bassil
- 5USDA-ARS National Clonal Germplasm Repository, Corvallis, OR 97333 USA
| | - Timo Hytönen
- 6Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, 00790 Finland
- 7Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, 00790 Finland
- NIAB EMR, Kent, ME19 6BJ UK
| | - Kathryn K Mackenzie
- 6Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, 00790 Finland
| | - Seonghee Lee
- 1University of Florida, Institute of Food and Agricultural Sciences, Gulf Coast Research and Education Center, Wimauma, Florida 33598 USA
| | - Sook Jung
- 9Department of Horticulture, Washington State University, Pullman, WA 99164 USA
| | - Dorrie Main
- 9Department of Horticulture, Washington State University, Pullman, WA 99164 USA
| | - Christopher R Barbey
- 1University of Florida, Institute of Food and Agricultural Sciences, Gulf Coast Research and Education Center, Wimauma, Florida 33598 USA
| | - Sujeet Verma
- 1University of Florida, Institute of Food and Agricultural Sciences, Gulf Coast Research and Education Center, Wimauma, Florida 33598 USA
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24
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Edger PP, McKain MR, Yocca AE, Knapp SJ, Qiao Q, Zhang T. Reply to: Revisiting the origin of octoploid strawberry. Nat Genet 2019; 52:5-7. [PMID: 31844320 PMCID: PMC6960091 DOI: 10.1038/s41588-019-0544-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 11/04/2019] [Indexed: 11/09/2022]
Affiliation(s)
- Patrick P Edger
- Department of Horticulture, Michigan State University, East Lansing, MI, USA. .,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI, USA.
| | - Michael R McKain
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | - Alan E Yocca
- Department of Horticulture, Michigan State University, East Lansing, MI, USA.,Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California-Davis, Davis, CA, USA
| | - Qin Qiao
- School of Agriculture, Yunnan University, Kunming, China.
| | - Ticao Zhang
- College of Chinese Material Medica, Yunnan University of Chinese Medicine, Kunming, China.
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25
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Petrasch S, Knapp SJ, van Kan JAL, Blanco‐Ulate B. Grey mould of strawberry, a devastating disease caused by the ubiquitous necrotrophic fungal pathogen Botrytis cinerea. Mol Plant Pathol 2019; 20:877-892. [PMID: 30945788 PMCID: PMC6637890 DOI: 10.1111/mpp.12794] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The fungal pathogen Botrytis cinerea causes grey mould, a commercially damaging disease of strawberry. This pathogen affects fruit in the field, storage, transport and market. The presence of grey mould is the most common reason for fruit rejection by growers, shippers and consumers, leading to significant economic losses. Here, we review the biology and epidemiology of the pathogen, mechanisms of infection and the genetics of host plant resistance. The development of grey mould is affected by environmental and genetic factors; however, little is known about how B. cinerea and strawberry interact at the molecular level. Despite intensive efforts, breeding strawberry for resistance to grey mould has not been successful, and the mechanisms underlying tolerance to B. cinerea are poorly understood and under-investigated. Current control strategies against grey mould include pre- and postharvest fungicides, yet they are generally ineffective and expensive. In this review, we examine available research on horticultural management, chemical and biological control of the pathogen in the field and postharvest storage, and discuss their relevance for integrative disease management. Additionally, we identify and propose approaches for increasing resistance to B. cinerea in strawberry by tapping into natural genetic variation and manipulating host factors via genetic engineering and genome editing.
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Affiliation(s)
- Stefan Petrasch
- Department of Plant SciencesUniversity of California, DavisDavisCAUSA
| | - Steven J. Knapp
- Department of Plant SciencesUniversity of California, DavisDavisCAUSA
| | - Jan A. L. van Kan
- Laboratory of PhytopathologyWageningen UniversityWageningenNetherlands
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26
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Edger PP, Poorten TJ, VanBuren R, Hardigan MA, Colle M, McKain MR, Smith RD, Teresi SJ, Nelson ADL, Wai CM, Alger EI, Bird KA, Yocca AE, Pumplin N, Ou S, Ben-Zvi G, Brodt A, Baruch K, Swale T, Shiue L, Acharya CB, Cole GS, Mower JP, Childs KL, Jiang N, Lyons E, Freeling M, Puzey JR, Knapp SJ. Author Correction: Origin and evolution of the octoploid strawberry genome. Nat Genet 2019; 51:765. [PMID: 30842601 PMCID: PMC7608257 DOI: 10.1038/s41588-019-0380-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Patrick P Edger
- Department of Horticulture, Michigan State University, East Lansing, MI, USA. .,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI, USA.
| | - Thomas J Poorten
- Department of Plant Sciences, University of California-Davis, Davis, CA, USA
| | - Robert VanBuren
- Department of Horticulture, Michigan State University, East Lansing, MI, USA.,Plant Resilience Institute, Michigan State University, East Lansing, MI, USA
| | - Michael A Hardigan
- Department of Plant Sciences, University of California-Davis, Davis, CA, USA
| | - Marivi Colle
- Department of Horticulture, Michigan State University, East Lansing, MI, USA
| | - Michael R McKain
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | - Ronald D Smith
- Department of Biology, College of William and Mary, Williamsburg, VA, USA
| | - Scott J Teresi
- Department of Biology, College of William and Mary, Williamsburg, VA, USA
| | | | - Ching Man Wai
- Department of Horticulture, Michigan State University, East Lansing, MI, USA
| | - Elizabeth I Alger
- Department of Horticulture, Michigan State University, East Lansing, MI, USA
| | - Kevin A Bird
- Department of Horticulture, Michigan State University, East Lansing, MI, USA.,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI, USA
| | - Alan E Yocca
- Department of Horticulture, Michigan State University, East Lansing, MI, USA
| | - Nathan Pumplin
- Department of Plant Sciences, University of California-Davis, Davis, CA, USA
| | - Shujun Ou
- Department of Horticulture, Michigan State University, East Lansing, MI, USA.,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI, USA
| | | | | | | | | | | | - Charlotte B Acharya
- Department of Plant Sciences, University of California-Davis, Davis, CA, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California-Davis, Davis, CA, USA
| | - Jeffrey P Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, USA
| | - Kevin L Childs
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA.,Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, MI, USA
| | - Ning Jiang
- Department of Horticulture, Michigan State University, East Lansing, MI, USA.,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI, USA
| | - Eric Lyons
- School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Michael Freeling
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Joshua R Puzey
- School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California-Davis, Davis, CA, USA.
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27
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Petrasch S, Silva CJ, Mesquida-Pesci SD, Gallegos K, van den Abeele C, Papin V, Fernandez-Acero FJ, Knapp SJ, Blanco-Ulate B. Infection Strategies Deployed by Botrytis cinerea, Fusarium acuminatum, and Rhizopus stolonifer as a Function of Tomato Fruit Ripening Stage. Front Plant Sci 2019; 10:223. [PMID: 30881367 PMCID: PMC6405687 DOI: 10.3389/fpls.2019.00223] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 02/08/2019] [Indexed: 05/12/2023]
Abstract
Worldwide, 20-25% of all harvested fruit and vegetables are lost annually in the field and throughout the postharvest supply chain due to rotting by fungal pathogens. Most postharvest pathogens exhibit necrotrophic or saprotrophic lifestyles, resulting in decomposition of the host tissues and loss of marketable commodities. Necrotrophic fungi can readily infect ripe fruit leading to the rapid establishment of disease symptoms. However, these pathogens generally fail to infect unripe fruit or remain quiescent until host conditions stimulate a successful infection. Previous research on infections of fruit has mainly been focused on the host's genetic and physicochemical factors that inhibit or promote disease. Here, we investigated if fruit pathogens can modify their own infection strategies in response to the ripening stage of the host. To test this hypothesis, we profiled global gene expression of three fungal pathogens that display necrotrophic behavior-Botrytis cinerea, Fusarium acuminatum, and Rhizopus stolonifer-during interactions with unripe and ripe tomato fruit. We assembled and functionally annotated the transcriptomes of F. acuminatum and R. stolonifer as no genomic resources were available. Then, we conducted differential gene expression analysis to compare each pathogen during inoculations versus in vitro conditions. Through characterizing patterns of overrepresented pathogenicity and virulence functions (e.g., phytotoxin production, cell wall degradation, and proteolysis) among the differentially expressed genes, we were able to determine shared strategies among the three fungi during infections of compatible (ripe) and incompatible (unripe) fruit tissues. Though each pathogen's strategy differed in the details, interactions with unripe fruit were commonly characterized by an emphasis on the degradation of cell wall components, particularly pectin, while colonization of ripe fruit featured more heavily redox processes, proteolysis, metabolism of simple sugars, and chitin biosynthesis. Furthermore, we determined that the three fungi were unable to infect fruit from the non-ripening (nor) tomato mutant, confirming that to cause disease, these pathogens require the host tissues to undergo specific ripening processes. By enabling a better understanding of fungal necrotrophic infection strategies, we move closer to generating accurate models of fruit diseases and the development of early detection tools and effective management strategies.
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Affiliation(s)
- Stefan Petrasch
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Christian J. Silva
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Saskia D. Mesquida-Pesci
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- Laboratory of Phytopathology, Wageningen University, Wageningen, Netherlands
| | - Karina Gallegos
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Casper van den Abeele
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- Laboratory of Plant Physiology, Wageningen University, Wageningen, Netherlands
| | - Victor Papin
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- Ecole Nationale Supérieure Agronomique de Toulouse, Toulouse, France
| | - Francisco J. Fernandez-Acero
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- Microbiology Laboratory, Institute of Viticulture and Agri-Food Research, Marine and Environmental Sciences Faculty, University of Cádiz, Cádiz, Spain
| | - Steven J. Knapp
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Barbara Blanco-Ulate
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
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28
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Edger PP, Poorten TJ, VanBuren R, Hardigan MA, Colle M, McKain MR, Smith RD, Teresi SJ, Nelson ADL, Wai CM, Alger EI, Bird KA, Yocca AE, Pumplin N, Ou S, Ben-Zvi G, Brodt A, Baruch K, Swale T, Shiue L, Acharya CB, Cole GS, Mower JP, Childs KL, Jiang N, Lyons E, Freeling M, Puzey JR, Knapp SJ. Origin and evolution of the octoploid strawberry genome. Nat Genet 2019; 51:541-547. [PMID: 30804557 PMCID: PMC6882729 DOI: 10.1038/s41588-019-0356-4] [Citation(s) in RCA: 304] [Impact Index Per Article: 60.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 01/15/2019] [Indexed: 01/19/2023]
Abstract
Cultivated strawberry emerged from the hybridization of two wild octoploid species, both descendants from the merger of four diploid progenitor species into a single nucleus more than 1 million years ago. Here we report a near-complete chromosome-scale assembly for cultivated octoploid strawberry (Fragaria × ananassa) and uncovered the origin and evolutionary processes that shaped this complex allopolyploid. We identified the extant relatives of each diploid progenitor species and provide support for the North American origin of octoploid strawberry. We examined the dynamics among the four subgenomes in octoploid strawberry and uncovered the presence of a single dominant subgenome with significantly greater gene content, gene expression abundance, and biased exchanges between homoeologous chromosomes, as compared with the other subgenomes. Pathway analysis showed that certain metabolomic and disease-resistance traits are largely controlled by the dominant subgenome. These findings and the reference genome should serve as a powerful platform for future evolutionary studies and enable molecular breeding in strawberry. Chromosome-scale assembly for the cultivated octoploid strawberry (Fragaria × ananassa) uncovers the origin and evolutionary processes that shaped this complex allopolyploid, providing a useful resource for genome-wide analyses and molecular breeding.
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Affiliation(s)
- Patrick P Edger
- Department of Horticulture, Michigan State University, East Lansing, MI, USA. .,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI, USA.
| | - Thomas J Poorten
- Department of Plant Sciences, University of California-Davis, Davis, California, USA
| | - Robert VanBuren
- Department of Horticulture, Michigan State University, East Lansing, MI, USA.,Plant Resilience Institute, Michigan State University, East Lansing, MI, USA
| | - Michael A Hardigan
- Department of Plant Sciences, University of California-Davis, Davis, California, USA
| | - Marivi Colle
- Department of Horticulture, Michigan State University, East Lansing, MI, USA
| | - Michael R McKain
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | - Ronald D Smith
- Department of Biology, College of William and Mary, Williamsburg, VA, USA
| | - Scott J Teresi
- Department of Biology, College of William and Mary, Williamsburg, VA, USA
| | | | - Ching Man Wai
- Department of Horticulture, Michigan State University, East Lansing, MI, USA
| | - Elizabeth I Alger
- Department of Horticulture, Michigan State University, East Lansing, MI, USA
| | - Kevin A Bird
- Department of Horticulture, Michigan State University, East Lansing, MI, USA.,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI, USA
| | - Alan E Yocca
- Department of Horticulture, Michigan State University, East Lansing, MI, USA
| | - Nathan Pumplin
- Department of Plant Sciences, University of California-Davis, Davis, California, USA
| | - Shujun Ou
- Department of Horticulture, Michigan State University, East Lansing, MI, USA.,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI, USA
| | | | | | | | | | | | - Charlotte B Acharya
- Department of Plant Sciences, University of California-Davis, Davis, California, USA
| | - Glenn S Cole
- Department of Plant Sciences, University of California-Davis, Davis, California, USA
| | - Jeffrey P Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, USA
| | - Kevin L Childs
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA.,Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, MI, USA
| | - Ning Jiang
- Department of Horticulture, Michigan State University, East Lansing, MI, USA.,Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, MI, USA
| | - Eric Lyons
- School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Michael Freeling
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Joshua R Puzey
- Department of Biology, College of William and Mary, Williamsburg, VA, USA
| | - Steven J Knapp
- Department of Plant Sciences, University of California-Davis, Davis, California, USA.
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29
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Hardigan MA, Feldmann MJ, Lorant A, Bird KA, Famula R, Acharya C, Cole G, Edger PP, Knapp SJ. Genome Synteny Has Been Conserved Among the Octoploid Progenitors of Cultivated Strawberry Over Millions of Years of Evolution. Front Plant Sci 2019; 10:1789. [PMID: 32158449 PMCID: PMC7020885 DOI: 10.3389/fpls.2019.01789] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 12/20/2019] [Indexed: 05/18/2023]
Abstract
Allo-octoploid cultivated strawberry (Fragaria × ananassa) originated through a combination of polyploid and homoploid hybridization, domestication of an interspecific hybrid lineage, and continued admixture of wild species over the last 300 years. While genes appear to flow freely between the octoploid progenitors, the genome structures and diversity of the octoploid species remain poorly understood. The complexity and absence of an octoploid genome frustrated early efforts to study chromosome evolution, resolve subgenomic structure, and develop a single coherent linkage group nomenclature. Here, we show that octoploid Fragaria species harbor millions of subgenome-specific DNA variants. Their diversity was sufficient to distinguish duplicated (homoeologous and paralogous) DNA sequences and develop 50K and 850K SNP genotyping arrays populated with co-dominant, disomic SNP markers distributed throughout the octoploid genome. Whole-genome shotgun genotyping of an interspecific segregating population yielded 1.9M genetically mapped subgenome variants in 5,521 haploblocks spanning 3,394 cM in F. chiloensis subsp. lucida, and 1.6M genetically mapped subgenome variants in 3,179 haploblocks spanning 2,017 cM in F. × ananassa. These studies provide a dense genomic framework of subgenome-specific DNA markers for seamlessly cross-referencing genetic and physical mapping information and unifying existing chromosome nomenclatures. Using comparative genomics, we show that geographically diverse wild octoploids are effectively diploidized, nearly completely collinear, and retain strong macro-synteny with diploid progenitor species. The preservation of genome structure among allo-octoploid taxa is a critical factor in the unique history of garden strawberry, where unimpeded gene flow supported its origin and domestication through repeated cycles of interspecific hybridization.
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Affiliation(s)
- Michael A. Hardigan
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Mitchell J. Feldmann
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Anne Lorant
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Kevin A. Bird
- Department of Horticulture, Michigan State University, East Lansing, MI, United States
| | - Randi Famula
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Charlotte Acharya
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Glenn Cole
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Patrick P. Edger
- Department of Horticulture, Michigan State University, East Lansing, MI, United States
| | - Steven J. Knapp
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- *Correspondence: Steven J. Knapp,
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Edger PP, VanBuren R, Colle M, Poorten TJ, Wai CM, Niederhuth CE, Alger EI, Ou S, Acharya CB, Wang J, Callow P, McKain MR, Shi J, Collier C, Xiong Z, Mower JP, Slovin JP, Hytönen T, Jiang N, Childs KL, Knapp SJ. Single-molecule sequencing and optical mapping yields an improved genome of woodland strawberry (Fragaria vesca) with chromosome-scale contiguity. Gigascience 2018; 7:1-7. [PMID: 29253147 PMCID: PMC5801600 DOI: 10.1093/gigascience/gix124] [Citation(s) in RCA: 154] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 11/30/2017] [Indexed: 12/18/2022] Open
Abstract
Background Although draft genomes are available for most agronomically important plant species, the majority are incomplete, highly fragmented, and often riddled with assembly and scaffolding errors. These assembly issues hinder advances in tool development for functional genomics and systems biology. Findings Here we utilized a robust, cost-effective approach to produce high-quality reference genomes. We report a near-complete genome of diploid woodland strawberry (Fragaria vesca) using single-molecule real-time sequencing from Pacific Biosciences (PacBio). This assembly has a contig N50 length of ∼7.9 million base pairs (Mb), representing a ∼300-fold improvement of the previous version. The vast majority (>99.8%) of the assembly was anchored to 7 pseudomolecules using 2 sets of optical maps from Bionano Genomics. We obtained ∼24.96 Mb of sequence not present in the previous version of the F. vesca genome and produced an improved annotation that includes 1496 new genes. Comparative syntenic analyses uncovered numerous, large-scale scaffolding errors present in each chromosome in the previously published version of the F. vesca genome. Conclusions Our results highlight the need to improve existing short-read based reference genomes. Furthermore, we demonstrate how genome quality impacts commonly used analyses for addressing both fundamental and applied biological questions.
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Affiliation(s)
- Patrick P Edger
- Department of Horticulture, Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823.,Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Robert VanBuren
- Department of Horticulture, Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Marivi Colle
- Department of Horticulture, Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Thomas J Poorten
- Department of Plant Sciences, University of California - Davis, Davis, California, 95616
| | - Ching Man Wai
- Department of Horticulture, Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Chad E Niederhuth
- Department of Genetics, University of Georgia, Athens, Georgia, 30602
| | - Elizabeth I Alger
- Department of Horticulture, Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Shujun Ou
- Department of Horticulture, Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823.,Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Charlotte B Acharya
- Department of Plant Sciences, University of California - Davis, Davis, California, 95616
| | - Jie Wang
- Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Pete Callow
- Department of Horticulture, Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Michael R McKain
- Donald Danforth Plant Science Center, St. Louis, Missouri, 63132
| | - Jinghua Shi
- Bionano Genomics, San Diego, California, 92121
| | | | - Zhiyong Xiong
- Potato Engineering and Technology Research Center, Inner Mongolia University, Hohhot, 010021, China
| | - Jeffrey P Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska, 68588
| | - Janet P Slovin
- USDA/ARS, Genetic Improvement of Fruits and Vegetables Laboratory, Beltsville, Maryland, 20705
| | - Timo Hytönen
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, 00014, Finland
| | - Ning Jiang
- Department of Horticulture, Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823.,Ecology, Evolutionary Biology, and Behavior, Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Kevin L Childs
- Department of Plant Biology, and Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823.,Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, Michigan, 48823
| | - Steven J Knapp
- Department of Plant Sciences, University of California - Davis, Davis, California, 95616
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31
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Hardigan MA, Poorten TJ, Acharya CB, Cole GS, Hummer KE, Bassil N, Edger PP, Knapp SJ. Domestication of Temperate and Coastal Hybrids with Distinct Ancestral Gene Selection in Octoploid Strawberry. Plant Genome 2018; 11:180049. [PMID: 30512037 DOI: 10.3835/plantgenome2018.07.0049] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Garden strawberry ( × Duchesne ex Rozier) arose from spontaneous hybridization of distinct octoploid species 300 yr ago. Since its discovery in the 1700s, migration and selection restructured the genetic diversity of early hybrids to produce elite fruit-bearing groups. Breeders' understanding of the genetic architecture of domesticated populations is incomplete. To resolve the impacts of domestication on strawberry genetic diversity, we analyzed genome-wide DNA profiles of 1300 octoploid individuals (1814-present), including wild species, historic varieties, and the University of California germplasm collection. Commercially important California genotypes, adapted to mild coastal climates and accounting for a large fraction of global production, have diverged from temperate cultivars originating in eastern North America and Europe. Whereas temperate cultivars were shown to have selected North American Miller ssp. ancestral diversity at higher frequencies, coastal breeding increased selection of (L.) Miller (beach strawberry) alleles in . × , in addition to photoperiod-insensitive flowering alleles from nonancestral (S.Watson) Staudt ssp. , underscoring the role of continued adaptive introgressions in the domestication of artificial hybrids. Selection for mass production traits in coastal climates over the last 20 to 30 yr has restructured domesticated strawberry diversity on a scale similar to the first 200 yr of breeding; coastal × has diverged further from temperate × than the latter from their wild progenitors. Selection signatures indicate that strawberry domestication targeted genes regulating hormone-mediated fruit expansion, providing a blueprint for genetic factors underlying elite phenotypes.
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32
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Slabaugh MB, Cooper LD, Kishore VK, Knapp SJ, Kling JG. Genes affecting novel seed constituents in Limnanthes alba Benth: transcriptome analysis of developing embryos and a new genetic map of meadowfoam. PeerJ 2015; 3:e915. [PMID: 26038713 PMCID: PMC4451031 DOI: 10.7717/peerj.915] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 04/06/2015] [Indexed: 01/19/2023] Open
Abstract
The seed oil of meadowfoam, a new crop in the Limnanthaceae family, is highly enriched in very long chain fatty acids that are desaturated at the Δ5 position. The unusual oil is desirable for cosmetics and innovative industrial applications and the seed meal remaining after oil extraction contains glucolimnanthin, a methoxylated benzylglucosinolate whose degradation products are herbicidal and anti-microbial. Here we describe EST analysis of the developing seed transcriptome that identified major genes involved in biosynthesis and assembly of the seed oil and in glucosinolate metabolic pathways. mRNAs encoding acyl-CoA Δ5 desaturase were notably abundant. The library was searched for simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs). Fifty-four new SSR markers and eight candidate gene markers were developed and combined with previously developed SSRs to construct a new genetic map for Limnanthes alba. Mapped genes in the lipid biosynthetic pathway encode 3-ketoacyl-CoA synthase (KCS), Δ5 desaturase (Δ5DS), lysophosphatidylacyl-acyl transferase (LPAT), and acyl-CoA diacylglycerol acyl transferase (DGAT). Mapped genes in glucosinolate biosynthetic and degradation pathways encode CYP79A, myrosinase (TGG), and epithiospecifier modifier protein (ESM). The resources developed in this study will further the domestication and improvement of meadowfoam as an oilseed crop.
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Affiliation(s)
- Mary B Slabaugh
- Department of Crop and Soil Science, Oregon State University , Corvallis, OR , United States of America
| | - Laurel D Cooper
- Department of Crop and Soil Science, Oregon State University , Corvallis, OR , United States of America ; Department of Botany and Plant Pathology, Oregon State University , Corvallis OR , United States of America
| | | | - Steven J Knapp
- Department of Plant Sciences, University of California-Davis , Davis, CA , United States of America
| | - Jennifer G Kling
- Department of Crop and Soil Science, Oregon State University , Corvallis, OR , United States of America
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Nambeesan SU, Mandel JR, Bowers JE, Marek LF, Ebert D, Corbi J, Rieseberg LH, Knapp SJ, Burke JM. Association mapping in sunflower (Helianthus annuus L.) reveals independent control of apical vs. basal branching. BMC Plant Biol 2015; 15:84. [PMID: 25887675 PMCID: PMC4407831 DOI: 10.1186/s12870-015-0458-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 02/13/2015] [Indexed: 05/20/2023]
Abstract
BACKGROUND Shoot branching is an important determinant of plant architecture and influences various aspects of growth and development. Selection on branching has also played an important role in the domestication of crop plants, including sunflower (Helianthus annuus L.). Here, we describe an investigation of the genetic basis of variation in branching in sunflower via association mapping in a diverse collection of cultivated sunflower lines. RESULTS Detailed phenotypic analyses revealed extensive variation in the extent and type of branching within the focal population. After correcting for population structure and kinship, association analyses were performed using a genome-wide collection of SNPs to identify genomic regions that influence a variety of branching-related traits. This work resulted in the identification of multiple previously unidentified genomic regions that contribute to variation in branching. Genomic regions that were associated with apical and mid-apical branching were generally distinct from those associated with basal and mid-basal branching. Homologs of known branching genes from other study systems (i.e., Arabidopsis, rice, pea, and petunia) were also identified from the draft assembly of the sunflower genome and their map positions were compared to those of associations identified herein. Numerous candidate branching genes were found to map in close proximity to significant branching associations. CONCLUSIONS In sunflower, variation in branching is genetically complex and overall branching patterns (i.e., apical vs. basal) were found to be influenced by distinct genomic regions. Moreover, numerous candidate branching genes mapped in close proximity to significant branching associations. Although the sunflower genome exhibits localized islands of elevated linkage disequilibrium (LD), these non-random associations are known to decay rapidly elsewhere. The subset of candidate genes that co-localized with significant associations in regions of low LD represents the most promising target for future functional analyses.
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Affiliation(s)
- Savithri U Nambeesan
- Department of Plant Biology, Miller Plant Sciences, University of Georgia, Athens, GA, 30602, USA.
- Present address: Department of Horticulture, University of Georgia, Athens, GA, 30602, USA.
| | - Jennifer R Mandel
- Department of Plant Biology, Miller Plant Sciences, University of Georgia, Athens, GA, 30602, USA.
- Present address: Department of Biological Sciences, University of Memphis, Memphis, TN, 38152, USA.
| | - John E Bowers
- Department of Plant Biology, Miller Plant Sciences, University of Georgia, Athens, GA, 30602, USA.
| | - Laura F Marek
- North Central Regional Plant Introduction Station, Iowa State University/USDA-ARS, Ames, IA, 50014, USA.
| | - Daniel Ebert
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Jonathan Corbi
- Department of Plant Biology, Miller Plant Sciences, University of Georgia, Athens, GA, 30602, USA.
- Present address: Department of Crop and Soil Sciences, University of Georgia, Athens, GA, 30602, USA.
| | - Loren H Rieseberg
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Steven J Knapp
- Department of Plant Sciences, University of California, Davis, CA, 95616, USA.
| | - John M Burke
- Department of Plant Biology, Miller Plant Sciences, University of Georgia, Athens, GA, 30602, USA.
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Brothers AN, Barb JG, Ballerini ES, Drury DW, Knapp SJ, Arnold ML. Genetic Architecture of Floral Traits in Iris hexagona and Iris fulva. J Hered 2013; 104:853-61. [DOI: 10.1093/jhered/est059] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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35
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Livaja M, Wang Y, Wieckhorst S, Haseneyer G, Seidel M, Hahn V, Knapp SJ, Taudien S, Schön CC, Bauer E. BSTA: a targeted approach combines bulked segregant analysis with next- generation sequencing and de novo transcriptome assembly for SNP discovery in sunflower. BMC Genomics 2013; 14:628. [PMID: 24330545 PMCID: PMC3848877 DOI: 10.1186/1471-2164-14-628] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 09/16/2013] [Indexed: 01/31/2023] Open
Abstract
Background Sunflower belongs to the largest plant family on earth, the genomically poorly explored Compositae. Downy mildew Plasmopara halstedii (Farlow) Berlese & de Toni is one of the major diseases of cultivated sunflower (Helianthus annuus L.). In the search for new sources of downy mildew resistance, the locus PlARG on linkage group 1 (LG1) originating from H. argophyllus is promising since it confers resistance against all known races of the pathogen. However, the mapping resolution in the PlARG region is hampered by significantly suppressed recombination and by limited availability of polymorphic markers. Here we examined a strategy developed for the enrichment of molecular markers linked to this specific genomic region. We combined bulked segregant analysis (BSA) with next-generation sequencing (NGS) and de novo assembly of the sunflower transcriptome for single nucleotide polymorphism (SNP) discovery in a sequence resource combining reads originating from two sunflower species, H. annuus and H. argophyllus. Results A computational pipeline developed for SNP calling and pattern detection identified 219 candidate genes. For a proof of concept, 42 resistance gene-like sequences were subjected to experimental SNP validation. Using a high-resolution mapping population, 12 SNP markers were mapped to LG1. We successfully verified candidate sequences either co-segregating with or closely flanking PlARG. Conclusions This study is the first successful example to improve bulked segregant analysis with de novo transcriptome assembly using next generation sequencing. The BSTA pipeline we developed provides a useful guide for similar studies in other non-model organisms. Our results demonstrate this method is an efficient way to enrich molecular markers and to identify candidate genes in a specific mapping interval.
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36
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Mandel JR, Nambeesan S, Bowers JE, Marek LF, Ebert D, Rieseberg LH, Knapp SJ, Burke JM. Association mapping and the genomic consequences of selection in sunflower. PLoS Genet 2013; 9:e1003378. [PMID: 23555290 PMCID: PMC3605098 DOI: 10.1371/journal.pgen.1003378] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 01/29/2013] [Indexed: 11/18/2022] Open
Abstract
The combination of large-scale population genomic analyses and trait-based mapping approaches has the potential to provide novel insights into the evolutionary history and genome organization of crop plants. Here, we describe the detailed genotypic and phenotypic analysis of a sunflower (Helianthus annuus L.) association mapping population that captures nearly 90% of the allelic diversity present within the cultivated sunflower germplasm collection. We used these data to characterize overall patterns of genomic diversity and to perform association analyses on plant architecture (i.e., branching) and flowering time, successfully identifying numerous associations underlying these agronomically and evolutionarily important traits. Overall, we found variable levels of linkage disequilibrium (LD) across the genome. In general, islands of elevated LD correspond to genomic regions underlying traits that are known to have been targeted by selection during the evolution of cultivated sunflower. In many cases, these regions also showed significantly elevated levels of differentiation between the two major sunflower breeding groups, consistent with the occurrence of divergence due to strong selection. One of these regions, which harbors a major branching locus, spans a surprisingly long genetic interval (ca. 25 cM), indicating the occurrence of an extended selective sweep in an otherwise recombinogenic interval.
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Affiliation(s)
- Jennifer R. Mandel
- Department of Plant Biology, Miller Plant Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Savithri Nambeesan
- Department of Plant Biology, Miller Plant Sciences, University of Georgia, Athens, Georgia, United States of America
| | - John E. Bowers
- Department of Plant Biology, Miller Plant Sciences, University of Georgia, Athens, Georgia, United States of America
| | - Laura F. Marek
- North Central Regional Plant Introduction Station, USDA–ARS, Ames, Iowa, United States of America
| | - Daniel Ebert
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Loren H. Rieseberg
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Steven J. Knapp
- Monsanto Company, Woodland, California, United States of America
| | - John M. Burke
- Department of Plant Biology, Miller Plant Sciences, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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Kane NC, Burke JM, Marek L, Seiler G, Vear F, Baute G, Knapp SJ, Vincourt P, Rieseberg LH. Sunflower genetic, genomic and ecological resources. Mol Ecol Resour 2013. [PMID: 23039950 DOI: 10.11111/1755-0998.12023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
Long a major focus of genetic research and breeding, sunflowers (Helianthus) are emerging as an increasingly important experimental system for ecological and evolutionary studies. Here, we review the various attributes of wild and domesticated sunflowers that make them valuable for ecological experimentation and describe the numerous publicly available resources that have enabled rapid advances in ecological and evolutionary genetics. Resources include seed collections available from germplasm centres at the USDA and INRA, genomic and EST sequences, mapping populations, genetic markers, genetic and physical maps and other forward- and reverse-genetic tools. We also discuss some of the key evolutionary, genetic and ecological questions being addressed in sunflowers, as well as gaps in our knowledge and promising areas for future research.
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Affiliation(s)
- Nolan C Kane
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO 80309, USA.
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Guo Y, Khanal S, Tang S, Bowers JE, Heesacker AF, Khalilian N, Nagy ED, Zhang D, Taylor CA, Stalker HT, Ozias-Akins P, Knapp SJ. Comparative mapping in intraspecific populations uncovers a high degree of macrosynteny between A- and B-genome diploid species of peanut. BMC Genomics 2012; 13:608. [PMID: 23140574 PMCID: PMC3532320 DOI: 10.1186/1471-2164-13-608] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 10/31/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Cultivated peanut or groundnut (Arachis hypogaea L.) is an important oilseed crop with an allotetraploid genome (AABB, 2n = 4x = 40). Both the low level of genetic variation within the cultivated gene pool and its polyploid nature limit the utilization of molecular markers to explore genome structure and facilitate genetic improvement. Nevertheless, a wealth of genetic diversity exists in diploid Arachis species (2n = 2x = 20), which represent a valuable gene pool for cultivated peanut improvement. Interspecific populations have been used widely for genetic mapping in diploid species of Arachis. However, an intraspecific mapping strategy was essential to detect chromosomal rearrangements among species that could be obscured by mapping in interspecific populations. To develop intraspecific reference linkage maps and gain insights into karyotypic evolution within the genus, we comparatively mapped the A- and B-genome diploid species using intraspecific F2 populations. Exploring genome organization among diploid peanut species by comparative mapping will enhance our understanding of the cultivated tetraploid peanut genome. Moreover, new sources of molecular markers that are highly transferable between species and developed from expressed genes will be required to construct saturated genetic maps for peanut. RESULTS A total of 2,138 EST-SSR (expressed sequence tag-simple sequence repeat) markers were developed by mining a tetraploid peanut EST assembly including 101,132 unigenes (37,916 contigs and 63,216 singletons) derived from 70,771 long-read (Sanger) and 270,957 short-read (454) sequences. A set of 97 SSR markers were also developed by mining 9,517 genomic survey sequences of Arachis. An SSR-based intraspecific linkage map was constructed using an F2 population derived from a cross between K 9484 (PI 298639) and GKBSPSc 30081 (PI 468327) in the B-genome species A. batizocoi. A high degree of macrosynteny was observed when comparing the homoeologous linkage groups between A (A. duranensis) and B (A. batizocoi) genomes. Comparison of the A- and B-genome genetic linkage maps also showed a total of five inversions and one major reciprocal translocation between two pairs of chromosomes under our current mapping resolution. CONCLUSIONS Our findings will contribute to understanding tetraploid peanut genome origin and evolution and eventually promote its genetic improvement. The newly developed EST-SSR markers will enrich current molecular marker resources in peanut.
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Affiliation(s)
- Yufang Guo
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
- Department of Horticulture, The University of Georgia, Tifton, GA, 31973, USA
| | - Sameer Khanal
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
| | - Shunxue Tang
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
| | - John E Bowers
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
| | - Adam F Heesacker
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
| | - Nelly Khalilian
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
| | - Ervin D Nagy
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
| | - Dong Zhang
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
| | - Christopher A Taylor
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
| | - H Thomas Stalker
- Department of Crop Science, North Carolina State University, Raleigh, NC, 27695, USA
| | - Peggy Ozias-Akins
- Department of Horticulture, The University of Georgia, Tifton, GA, 31973, USA
| | - Steven J Knapp
- Institute of Plant Breeding, Genetics, and Genomics, 111 Riverbend Road, The University of Georgia, Athens, GA, 30602, USA
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Mandel JR, Milton EF, Donovan LA, Knapp SJ, Burke JM. Genetic diversity and population structure in the rare Algodones sunflower (Helianthus niveus ssp. tephrodes). CONSERV GENET 2012. [DOI: 10.1007/s10592-012-0421-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Kane NC, Burke JM, Marek L, Seiler G, Vear F, Baute G, Knapp SJ, Vincourt P, Rieseberg LH. Sunflower genetic, genomic and ecological resources. Mol Ecol Resour 2012; 13:10-20. [PMID: 23039950 DOI: 10.1111/1755-0998.12023] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 08/22/2012] [Accepted: 08/24/2012] [Indexed: 11/29/2022]
Abstract
Long a major focus of genetic research and breeding, sunflowers (Helianthus) are emerging as an increasingly important experimental system for ecological and evolutionary studies. Here, we review the various attributes of wild and domesticated sunflowers that make them valuable for ecological experimentation and describe the numerous publicly available resources that have enabled rapid advances in ecological and evolutionary genetics. Resources include seed collections available from germplasm centres at the USDA and INRA, genomic and EST sequences, mapping populations, genetic markers, genetic and physical maps and other forward- and reverse-genetic tools. We also discuss some of the key evolutionary, genetic and ecological questions being addressed in sunflowers, as well as gaps in our knowledge and promising areas for future research.
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Affiliation(s)
- Nolan C Kane
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO 80309, USA.
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Ali MS, Knapp SJ. Cytogenetics off interpopulation Cuphea lanceolata hybrids. Genome 2012; 38:1148-52. [PMID: 18470238 DOI: 10.1139/g95-152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cuphea lanceolata Ait. (Lythraceae) is an annual diploid (x = 6) with medium-chain fatty acid rich seed oils. Wild C. lanceolata populations are classified as C. lanceolata f. silenoides or C. lanceolata f. lanceolata on the basis of flower pigment differences. Although these taxa are taxonomically close, their interfertility has not been demonstrated. We describe meiotic phenomena underlying the sterility of hybrids between C. lanceolata f. silenoides (LNS-43) and C. lanceolata f. lanceolata (LNC-78) populations. We assayed metaphase and anaphase I microsporocytes of the parent and hybrid populations. The hybrids were female and male sterile. The mean percentage of stainable pollen was 94.9% for the parents and 1.1% for the hybrids. Chromosomes paired and disjoined normally in the parents (LNS-43 and LNC-78) and abnormally in the hybrids (LNS-43 x LNC-78 and LNC-78 x LNS-43). Univalents, unequal chromosome distributions, and laggards were observed in the hybrids. The mean number of univalents per cell was 0.00 for the parents and 5.95 for the hybrids, the mean number of bivalents per cell was 6.00 for the parents and 1.51 for the hybrids, and the mean number of chiasmata per cell was 9.19 for the parents and 4.04 for the hybrids. The most frequently observed (75%) anaphase I chromosome distribution for the hybrids was 7:5:0 (pole-pole-laggards). The genome affinities of the hybrids were half those of the parents (a mean of 0.5 for the hybrids as opposed to 1.0 for the parents). Although C. lanceolata f. silenoides and C. lanceolata f. lanceolata freely hybridize, their progeny are sterile, and the genetic diversity of LNC-78, and perhaps of C. lanceolata f. lanceolata as a whole, cannot be accessed through hybrids with C. lanceolata f. silenoides or C. viscosissima.
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Scaglione D, Lanteri S, Acquadro A, Lai Z, Knapp SJ, Rieseberg L, Portis E. Large-scale transcriptome characterization and mass discovery of SNPs in globe artichoke and its related taxa. Plant Biotechnol J 2012; 10:956-69. [PMID: 22849342 DOI: 10.1111/j.1467-7652.2012.00725.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Cynara cardunculus (2n = 2× = 34) is a member of the Asteraceae family that contributes significantly to the agricultural economy of the Mediterranean basin. The species includes two cultivated varieties, globe artichoke and cardoon, which are grown mainly for food. Cynara cardunculus is an orphan crop species whose genome/transcriptome has been relatively unexplored, especially in comparison to other Asteraceae crops. Hence, there is a significant need to improve its genomic resources through the identification of novel genes and sequence-based markers, to design new breeding schemes aimed at increasing quality and crop productivity. We report the outcome of cDNA sequencing and assembly for eleven accessions of C. cardunculus. Sequencing of three mapping parental genotypes using Roche 454-Titanium technology generated 1.7 × 10⁶ reads, which were assembled into 38,726 reference transcripts covering 32 Mbp. Putative enzyme-encoding genes were annotated using the KEGG-database. Transcription factors and candidate resistance genes were surveyed as well. Paired-end sequencing was done for cDNA libraries of eight other representative C. cardunculus accessions on an Illumina Genome Analyzer IIx, generating 46 × 10⁶ reads. Alignment of the IGA and 454 reads to reference transcripts led to the identification of 195,400 SNPs with a Bayesian probability exceeding 95%; a validation rate of 90% was obtained by Sanger-sequencing of a subset of contigs. These results demonstrate that the integration of data from different NGS platforms enables large-scale transcriptome characterization, along with massive SNP discovery. This information will contribute to the dissection of key agricultural traits in C. cardunculus and facilitate the implementation of marker-assisted selection programs.
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Staton SE, Bakken BH, Blackman BK, Chapman MA, Kane NC, Tang S, Ungerer MC, Knapp SJ, Rieseberg LH, Burke JM. The sunflower (Helianthus annuus L.) genome reflects a recent history of biased accumulation of transposable elements. Plant J 2012; 72:142-53. [PMID: 22691070 DOI: 10.1111/j.1365-313x.2012.05072.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Aside from polyploidy, transposable elements are the major drivers of genome size increases in plants. Thus, understanding the diversity and evolutionary dynamics of transposable elements in sunflower (Helianthus annuus L.), especially given its large genome size (∼3.5 Gb) and the well-documented cases of amplification of certain transposons within the genus, is of considerable importance for understanding the evolutionary history of this emerging model species. By analyzing approximately 25% of the sunflower genome from random sequence reads and assembled bacterial artificial chromosome (BAC) clones, we show that it is composed of over 81% transposable elements, 77% of which are long terminal repeat (LTR) retrotransposons. Moreover, the LTR retrotransposon fraction in BAC clones harboring genes is disproportionately composed of chromodomain-containing Gypsy LTR retrotransposons ('chromoviruses'), and the majority of the intact chromoviruses contain tandem chromodomain duplications. We show that there is a bias in the efficacy of homologous recombination in removing LTR retrotransposon DNA, thereby providing insight into the mechanisms associated with transposable element (TE) composition in the sunflower genome. We also show that the vast majority of observed LTR retrotransposon insertions have likely occurred since the origin of this species, providing further evidence that biased LTR retrotransposon activity has played a major role in shaping the chromatin and DNA landscape of the sunflower genome. Although our findings on LTR retrotransposon age and structure could be influenced by the selection of the BAC clones analyzed, a global analysis of random sequence reads indicates that the evolutionary patterns described herein apply to the sunflower genome as a whole.
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Affiliation(s)
- S Evan Staton
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
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Nagy ED, Guo Y, Tang S, Bowers JE, Okashah RA, Taylor CA, Zhang D, Khanal S, Heesacker AF, Khalilian N, Farmer AD, Carrasquilla-Garcia N, Penmetsa RV, Cook D, Stalker HT, Nielsen N, Ozias-Akins P, Knapp SJ. A high-density genetic map of Arachis duranensis, a diploid ancestor of cultivated peanut. BMC Genomics 2012; 13:469. [PMID: 22967170 PMCID: PMC3542255 DOI: 10.1186/1471-2164-13-469] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 08/30/2012] [Indexed: 01/06/2023] Open
Abstract
Background Cultivated peanut (Arachis hypogaea) is an allotetraploid species whose ancestral genomes are most likely derived from the A-genome species, A. duranensis, and the B-genome species, A. ipaensis. The very recent (several millennia) evolutionary origin of A. hypogaea has imposed a bottleneck for allelic and phenotypic diversity within the cultigen. However, wild diploid relatives are a rich source of alleles that could be used for crop improvement and their simpler genomes can be more easily analyzed while providing insight into the structure of the allotetraploid peanut genome. The objective of this research was to establish a high-density genetic map of the diploid species A. duranensis based on de novo generated EST databases. Arachis duranensis was chosen for mapping because it is the A-genome progenitor of cultivated peanut and also in order to circumvent the confounding effects of gene duplication associated with allopolyploidy in A. hypogaea. Results More than one million expressed sequence tag (EST) sequences generated from normalized cDNA libraries of A. duranensis were assembled into 81,116 unique transcripts. Mining this dataset, 1236 EST-SNP markers were developed between two A. duranensis accessions, PI 475887 and Grif 15036. An additional 300 SNP markers also were developed from genomic sequences representing conserved legume orthologs. Of the 1536 SNP markers, 1054 were placed on a genetic map. In addition, 598 EST-SSR markers identified in A. hypogaea assemblies were included in the map along with 37 disease resistance gene candidate (RGC) and 35 other previously published markers. In total, 1724 markers spanning 1081.3 cM over 10 linkage groups were mapped. Gene sequences that provided mapped markers were annotated using similarity searches in three different databases, and gene ontology descriptions were determined using the Medicago Gene Atlas and TAIR databases. Synteny analysis between A. duranensis, Medicago and Glycine revealed significant stretches of conserved gene clusters spread across the peanut genome. A higher level of colinearity was detected between A. duranensis and Glycine than with Medicago. Conclusions The first high-density, gene-based linkage map for A. duranensis was generated that can serve as a reference map for both wild and cultivated Arachis species. The markers developed here are valuable resources for the peanut, and more broadly, to the legume research community. The A-genome map will have utility for fine mapping in other peanut species and has already had application for mapping a nematode resistance gene that was introgressed into A. hypogaea from A. cardenasii.
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Affiliation(s)
- Ervin D Nagy
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia,111 Riverbend Rd, Athens, GA 30605, USA
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Ballerini ES, Brothers AN, Tang S, Knapp SJ, Bouck A, Taylor SJ, Arnold ML, Martin NH. QTL mapping reveals the genetic architecture of loci affecting pre- and post-zygotic isolating barriers in Louisiana Iris. BMC Plant Biol 2012; 12:91. [PMID: 22702308 PMCID: PMC3490880 DOI: 10.1186/1471-2229-12-91] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 05/18/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND Hybridization among Louisiana Irises has been well established and the genetic architecture of reproductive isolation is known to affect the potential for and the directionality of introgression between taxa. Here we use co-dominant markers to identify regions where QTL are located both within and between backcross maps to compare the genetic architecture of reproductive isolation and fitness traits across treatments and years. RESULTS QTL mapping was used to elucidate the genetic architecture of reproductive isolation between Iris fulva and Iris brevicaulis. Homologous co-dominant EST-SSR markers scored in two backcross populations between I. fulva and I. brevicaulis were used to generate genetic linkage maps. These were used as the framework for mapping QTL associated with variation in 11 phenotypic traits likely responsible for reproductive isolation and fitness. QTL were dispersed throughout the genome, with the exception of one region of a single linkage group (LG) where QTL for flowering time, sterility, and fruit production clustered. In most cases, homologous QTL were not identified in both backcross populations, however, homologous QTL for flowering time, number of growth points per rhizome, number of nodes per inflorescence, and number of flowers per node were identified on several linkage groups. CONCLUSIONS Two different traits affecting reproductive isolation, flowering time and sterility, exhibit different genetic architectures, with numerous QTL across the Iris genome controlling flowering time and fewer, less distributed QTL affecting sterility. QTL for traits affecting fitness are largely distributed across the genome with occasional overlap, especially on LG 4, where several QTL increasing fitness and decreasing sterility cluster. Given the distribution and effect direction of QTL affecting reproductive isolation and fitness, we have predicted genomic regions where introgression may be more likely to occur (those regions associated with an increase in fitness and unlinked to loci controlling reproductive isolation) and those that are less likely to exhibit introgression (those regions linked to traits decreasing fitness and reproductive isolation).
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Affiliation(s)
| | | | | | | | | | - Sunni J Taylor
- Department of Biology, Texas State University, San Marcos, TX, USA
| | | | - Noland H Martin
- Department of Biology, Texas State University, San Marcos, TX, USA
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Bachlava E, Taylor CA, Tang S, Bowers JE, Mandel JR, Burke JM, Knapp SJ. SNP discovery and development of a high-density genotyping array for sunflower. PLoS One 2012; 7:e29814. [PMID: 22238659 PMCID: PMC3251610 DOI: 10.1371/journal.pone.0029814] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 12/06/2011] [Indexed: 11/23/2022] Open
Abstract
Recent advances in next-generation DNA sequencing technologies have made possible the development of high-throughput SNP genotyping platforms that allow for the simultaneous interrogation of thousands of single-nucleotide polymorphisms (SNPs). Such resources have the potential to facilitate the rapid development of high-density genetic maps, and to enable genome-wide association studies as well as molecular breeding approaches in a variety of taxa. Herein, we describe the development of a SNP genotyping resource for use in sunflower (Helianthus annuus L.). This work involved the development of a reference transcriptome assembly for sunflower, the discovery of thousands of high quality SNPs based on the generation and analysis of ca. 6 Gb of transcriptome re-sequencing data derived from multiple genotypes, the selection of 10,640 SNPs for inclusion in the genotyping array, and the use of the resulting array to screen a diverse panel of sunflower accessions as well as related wild species. The results of this work revealed a high frequency of polymorphic SNPs and relatively high level of cross-species transferability. Indeed, greater than 95% of successful SNP assays revealed polymorphism, and more than 90% of these assays could be successfully transferred to related wild species. Analysis of the polymorphism data revealed patterns of genetic differentiation that were largely congruent with the evolutionary history of sunflower, though the large number of markers allowed for finer resolution than has previously been possible.
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Affiliation(s)
- Eleni Bachlava
- Center for Applied Genetic Technologies, University of Georgia, Athens, Georgia, United States of America
| | - Christopher A. Taylor
- Center for Applied Genetic Technologies, University of Georgia, Athens, Georgia, United States of America
| | - Shunxue Tang
- Center for Applied Genetic Technologies, University of Georgia, Athens, Georgia, United States of America
| | - John E. Bowers
- Center for Applied Genetic Technologies, University of Georgia, Athens, Georgia, United States of America
- Department of Plant Biology, University of Georgia, Athens, Georgia, United States of America
| | - Jennifer R. Mandel
- Department of Plant Biology, University of Georgia, Athens, Georgia, United States of America
| | - John M. Burke
- Department of Plant Biology, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
| | - Steven J. Knapp
- Center for Applied Genetic Technologies, University of Georgia, Athens, Georgia, United States of America
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Scaglione D, Acquadro A, Portis E, Tirone M, Knapp SJ, Lanteri S. RAD tag sequencing as a source of SNP markers in Cynara cardunculus L. BMC Genomics 2012; 13:3. [PMID: 22214349 PMCID: PMC3269995 DOI: 10.1186/1471-2164-13-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2011] [Accepted: 01/03/2012] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The globe artichoke (Cynara cardunculus L. var. scolymus) genome is relatively poorly explored, especially compared to those of the other major Asteraceae crops sunflower and lettuce. No SNP markers are in the public domain. We have combined the recently developed restriction-site associated DNA (RAD) approach with the Illumina DNA sequencing platform to effect the rapid and mass discovery of SNP markers for C. cardunculus. RESULTS RAD tags were sequenced from the genomic DNA of three C. cardunculus mapping population parents, generating 9.7 million reads, corresponding to ~1 Gbp of sequence. An assembly based on paired ends produced ~6.0 Mbp of genomic sequence, separated into ~19,000 contigs (mean length 312 bp), of which ~21% were fragments of putative coding sequence. The shared sequences allowed for the discovery of ~34,000 SNPs and nearly 800 indels, equivalent to a SNP frequency of 5.6 per 1,000 nt, and an indel frequency of 0.2 per 1,000 nt. A sample of heterozygous SNP loci was mapped by CAPS assays and this exercise provided validation of our mining criteria. The repetitive fraction of the genome had a high representation of retrotransposon sequence, followed by simple repeats, AT-low complexity regions and mobile DNA elements. The genomic k-mers distribution and CpG rate of C. cardunculus, compared with data derived from three whole genome-sequenced dicots species, provided a further evidence of the random representation of the C. cardunculus genome generated by RAD sampling. CONCLUSION The RAD tag sequencing approach is a cost-effective and rapid method to develop SNP markers in a highly heterozygous species. Our approach permitted to generate a large and robust SNP datasets by the adoption of optimized filtering criteria.
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Affiliation(s)
- Davide Scaglione
- Di.Va.P.R.A. Plant Genetics and Breeding, University of Torino, via L. da Vinci 44, 10095 Grugliasco (Torino), Italy
| | - Alberto Acquadro
- Di.Va.P.R.A. Plant Genetics and Breeding, University of Torino, via L. da Vinci 44, 10095 Grugliasco (Torino), Italy
| | - Ezio Portis
- Di.Va.P.R.A. Plant Genetics and Breeding, University of Torino, via L. da Vinci 44, 10095 Grugliasco (Torino), Italy
| | - Matteo Tirone
- Di.Va.P.R.A. Plant Genetics and Breeding, University of Torino, via L. da Vinci 44, 10095 Grugliasco (Torino), Italy
| | - Steven J Knapp
- Institute for Plant Breeding, Genetics, and Genomics, University of Georgia, 111 Riverbend Rd., 30602 Athens, Georgia USA
| | - Sergio Lanteri
- Di.Va.P.R.A. Plant Genetics and Breeding, University of Torino, via L. da Vinci 44, 10095 Grugliasco (Torino), Italy
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Bachlava E, Radwan OE, Abratti G, Tang S, Gao W, Heesacker AF, Bazzalo ME, Zambelli A, Leon AJ, Knapp SJ. Downy mildew (Pl ( 8 ) and Pl ( 14 )) and rust (R ( Adv )) resistance genes reside in close proximity to tandemly duplicated clusters of non-TIR-like NBS-LRR-encoding genes on sunflower chromosomes 1 and 13. Theor Appl Genet 2011; 122:1211-21. [PMID: 21293840 DOI: 10.1007/s00122-010-1525-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 12/11/2010] [Indexed: 05/20/2023]
Abstract
Nucleotide binding site-leucine rich repeat (NBS-LRR) proteins are encoded by a ubiquitous gene family in sunflower and frequently harbor disease resistance genes. We investigated NBS-LRR-encoding resistance gene candidates (RGCs) flanking the downy mildew resistance genes Pl ( 8 ) and Pl ( 14 ) and the rust resistance gene R ( Adv ), which map on the NBS-LRR clusters of linkage groups 1 and 13 in sunflower genome. We shotgun sequenced bacterial artificial chromosome (BAC) clones proximal to Pl ( 8 ), Pl ( 14 ) , and R ( Adv ) and identified seven novel non-Toll/interleukin-1 receptor (TIR)-like NBS-LRR RGCs, which clustered with previously identified RGCs of linkage group 13 but were phylogenetically distant from the TIR- and non-TIR-NBS-LRR-encoding superfamilies of sunflower. Six of the seven predicted RGCs have intact open reading frames and reside in genomic segments with abundant transposable elements. The genomic localization and sequence similarity of the novel non-TIR-like predicted RGCs suggests that they originated from tandem duplications. RGCs in the proximity of Pl ( 8 ) and R ( Adv ) were likely introgressed from silverleaf sunflower genome, where the RGC cluster of linkage group 13 is duplicated in two independent chromosomes that have different architecture and level of recombination from the respective common sunflower chromosomes.
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Affiliation(s)
- Eleni Bachlava
- Institute of Plant Breeding, Genetics and Genomics, The University of Georgia, Athens, GA 30602, USA.
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Abstract
Following domestication, crop lineages typically undergo diversification either to adapt to disparate habitats or to fill novel agricultural roles. This process has produced the numerous varieties found in modern-day crop germplasm collections. Here, we mapped quantitative trait loci (QTLs) underlying unique traits in the Hopi sunflower, a primitive, Native American domesticate. These traits included a variety of achene (i.e., single-seeded fruit) characters as well as the extremely late flowering time of the Hopi sunflower. Composite interval mapping identified 42 QTLs underlying the 12 traits of interest. Although these QTLs were found on 10 of the 17 sunflower linkage groups, strong genetic correlations were evidenced by the clustering of QTLs across traits in certain genomic regions. The number of QTLs per trait ranged from 2 to 6, and the average QTL explained 14.7% of the variance (range: 2.5-46.9%). The apparent contribution of epistasis was minor, as has previously been observed for domestication-related traits. Unlike typical domestication-related traits in sunflower, the traits under consideration here exhibited a relatively simple genetic basis, with 2 QTL clusters being largely responsible for the unique characteristics of the Hopi sunflower. Based on the rarity of these traits in domesticated sunflower, it would appear that they evolved within the Hopi lineage following domestication. The simple genetic architecture of these traits may be a by-product of genetic constraints imposed by the genetically complex nature of domestication-related traits in sunflower, with the large number of domestication-related QTLs limiting the fraction of the genome that is available for subsequent diversification.
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Affiliation(s)
- David M Wills
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
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Tang S, Okashah RA, Knapp SJ, Arnold ML, Martin NH. Transmission ratio distortion results in asymmetric introgression in Louisiana Iris. BMC Plant Biol 2010; 10:48. [PMID: 20298609 PMCID: PMC2923522 DOI: 10.1186/1471-2229-10-48] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 03/18/2010] [Indexed: 05/03/2023]
Abstract
BACKGROUND Linkage maps are useful tools for examining both the genetic architecture of quantitative traits and the evolution of reproductive incompatibilities. We describe the generation of two genetic maps using reciprocal interspecific backcross 1 (BC1) mapping populations from crosses between Iris brevicaulis and Iris fulva. These maps were constructed using expressed sequence tag (EST)- derived codominant microsatellite markers. Such a codominant marker system allowed for the ability to link the two reciprocal maps, and compare patterns of transmission ratio distortion observed between the two. RESULTS Linkage mapping resulted in markers that coalesced into 21 linkage groups for each of the reciprocal backcross maps, presumably corresponding to the 21 haploid chromosomes of I. brevicaulis and I. fulva. The composite map was 1190.0-cM long, spanned 81% of the I. brevicaulis and I. fulva genomes, and had a mean density of 4.5 cM per locus. Transmission ratio distortion (TRD) was observed in 138 (48.5%) loci distributed in 19 of the 21 LGs in BCIB, BCIF, or both BC1 mapping populations. Of the distorted markers identified, I. fulva alleles were detected at consistently higher-than-expected frequencies in both mapping populations. CONCLUSIONS The observation that I. fulva alleles are overrepresented in both mapping populations suggests that I. fulva alleles are favored to introgress into I. brevicaulis genetic backgrounds, while I. brevicaulis alleles would tend to be prevented from introgressing into I. fulva. These data are consistent with the previously observed patterns of introgression in natural hybrid zones, where I. fulva alleles have been consistently shown to introgress across species boundaries.
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Affiliation(s)
- Shunxue Tang
- Center for Applied Genetic Technologies, The University of Georgia, Athens, GA 30602, USA
- Dow AgroSciences LLC, Indianapolis, IN 46268, USA
| | - Rebecca A Okashah
- Center for Applied Genetic Technologies, The University of Georgia, Athens, GA 30602, USA
| | - Steven J Knapp
- Center for Applied Genetic Technologies, The University of Georgia, Athens, GA 30602, USA
| | - Michael L Arnold
- Department of Genetics, The University of Georgia, Athens, GA 30602, USA
| | - Noland H Martin
- Department of Biology, Texas State University - San Marcos, San Marcos, TX 78666, USA
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