1
|
Tränkner C, Pfeiffer N, Kirchhoff M, Kopisch-Obuch FJ, van Dijk H, Schilhabel M, Hasler M, Emrani N. Deciphering the complex nature of bolting time regulation in Beta vulgaris. Theor Appl Genet 2017; 130:1649-1667. [PMID: 28478574 DOI: 10.1007/s00122-017-2916-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 04/27/2017] [Indexed: 06/07/2023]
Abstract
Only few genetic loci are sufficient to increase the variation of bolting time in Beta vulgaris dramatically, regarding vernalization requirement, seasonal bolting time and reproduction type. Beta species show a wide variation of bolting time regarding the year of first reproduction, seasonal bolting time and the number of reproduction cycles. To elucidate the genetics of bolting time control, we used three F3 mapping populations that were produced by crossing a semelparous, annual sugar beet with iteroparous, vernalization-requiring wild beet genotypes. The semelparous plants died after reproduction, whereas iteroparous plants reproduced at least twice. All populations segregated for vernalization requirement, seasonal bolting time and the number of reproduction cycles. We found that vernalization requirement co-segregated with the bolting locus B on chromosome 2 and was inherited independently from semel- or iteroparous reproduction. Furthermore, we found that seasonal bolting time is a highly heritable trait (h 2 > 0.84), which is primarily controlled by two major QTL located on chromosome 4 and 9. Late bolting alleles of both loci act in a partially recessive manner and were identified in both iteroparous pollinators. We observed an additive interaction of both loci for bolting delay. The QTL region on chromosome 4 encompasses the floral promoter gene BvFT2, whereas the QTL on chromosome 9 co-localizes with the BR 1 locus, which controls post-winter bolting resistance. Our findings are applicable for marker-assisted sugar beet breeding regarding early bolting to accelerate generation cycles and late bolting to develop bolting-resistant spring and winter beets. Unexpectedly, one population segregated also for dwarf growth that was found to be controlled by a single locus on chromosome 9.
Collapse
Affiliation(s)
- Conny Tränkner
- Plant Breeding Institute, University of Kiel, Am Botanischen Garten 1-9, 24118, Kiel, Germany.
- Leibniz Institute of Vegetable and Ornamental Crops, Kühnhäuser Straße 101, 99090, Erfurt, Germany.
| | - Nina Pfeiffer
- Plant Breeding Institute, University of Kiel, Am Botanischen Garten 1-9, 24118, Kiel, Germany
- KWS LOCHOW GMBH, Zuchtstation Wetze, 37154, Northeim, Germany
| | - Martin Kirchhoff
- Plant Breeding Institute, University of Kiel, Am Botanischen Garten 1-9, 24118, Kiel, Germany
- Nordsaat Saatzucht GmbH, Böhnshauser Straße 1, 38895, Langenstein, Germany
| | - Friedrich J Kopisch-Obuch
- Plant Breeding Institute, University of Kiel, Am Botanischen Garten 1-9, 24118, Kiel, Germany
- KWS SAAT SE, Grimsehlstraße 31, 37555, Einbeck, Germany
| | - Henk van Dijk
- Universite Lille, CNRS, UMR 8198 - Evo-Eco-Paleo, 59000, Lille, France
| | - Markus Schilhabel
- Institute of Clinical Molecular Biology, University of Kiel, Schittenhelmstr. 12, 24105, Kiel, Germany
| | - Mario Hasler
- Lehrfach Variationsstatistik, University of Kiel, Hermann-Rodewald-Straße 9, 24098, Kiel, Germany
| | - Nazgol Emrani
- Plant Breeding Institute, University of Kiel, Am Botanischen Garten 1-9, 24118, Kiel, Germany
| |
Collapse
|
2
|
Capistrano-Gossmann GG, Ries D, Holtgräwe D, Minoche A, Kraft T, Frerichmann SLM, Rosleff Soerensen T, Dohm JC, González I, Schilhabel M, Varrelmann M, Tschoep H, Uphoff H, Schütze K, Borchardt D, Toerjek O, Mechelke W, Lein JC, Schechert AW, Frese L, Himmelbauer H, Weisshaar B, Kopisch-Obuch FJ. Crop wild relative populations of Beta vulgaris allow direct mapping of agronomically important genes. Nat Commun 2017; 8:15708. [PMID: 28585529 PMCID: PMC5467160 DOI: 10.1038/ncomms15708] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [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: 08/02/2016] [Accepted: 04/21/2017] [Indexed: 01/13/2023] Open
Abstract
Rapid identification of agronomically important genes is of pivotal interest for crop breeding. One source of such genes are crop wild relative (CWR) populations. Here we used a CWR population of <200 wild beets (B. vulgaris ssp. maritima), sampled in their natural habitat, to identify the sugar beet (Beta vulgaris ssp. vulgaris) resistance gene Rz2 with a modified version of mapping-by-sequencing (MBS). For that, we generated a draft genome sequence of the wild beet. Our results show the importance of preserving CWR in situ and demonstrate the great potential of CWR for rapid discovery of causal genes relevant for crop improvement. The candidate gene for Rz2 was identified by MBS and subsequently corroborated via RNA interference (RNAi). Rz2 encodes a CC-NB-LRR protein. Access to the DNA sequence of Rz2 opens the path to improvement of resistance towards rhizomania not only by marker-assisted breeding but also by genome editing. Variation among wild relatives of crop plants can be used to identify genes underlying traits of agronomic importance. Here, the authors show that a modified mapping-by-sequencing approach can rapidly identify the genetic basis for viral resistance in sugar beet using wild beet populations in their natural habitat.
Collapse
Affiliation(s)
| | - D Ries
- CeBiTec &Faculty of Biology, Bielefeld University, Universitätsstraße 25, Bielefeld 33615, Germany
| | - D Holtgräwe
- CeBiTec &Faculty of Biology, Bielefeld University, Universitätsstraße 25, Bielefeld 33615, Germany
| | - A Minoche
- Max Planck Institute for Molecular Genetics, Ihnestraße 73, Berlin 14195, Germany.,Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney NSW 2010, Australia
| | - T Kraft
- Syngenta Seeds AB, Box 302, Landskrona 26123, Sweden
| | - S L M Frerichmann
- Plant Breeding Institute, Kiel University, Am Botanischen Garten 1-9, Kiel 24118, Germany
| | - T Rosleff Soerensen
- CeBiTec &Faculty of Biology, Bielefeld University, Universitätsstraße 25, Bielefeld 33615, Germany
| | - J C Dohm
- Department of Biotechnology, University of Natural Resources and Life Sciences (BOKU), Muthgasse 18, 1190 Vienna, Austria
| | - I González
- Centre for Genomic Regulation (CRG), Carrer del Dr. Aiguader 88, Barcelona 08003, Spain
| | - M Schilhabel
- Plant Breeding Institute, Kiel University, Am Botanischen Garten 1-9, Kiel 24118, Germany
| | - M Varrelmann
- Department of Phytopathology, Institute of Sugar Beet Research (IfZ), Holtenser Landstraße 77, Göttingen 37079, Germany
| | - H Tschoep
- SESVanderHave N.V., Industriepark, Tienen 3300, Belgium
| | - H Uphoff
- Syngenta Seeds AB, Box 302, Landskrona 26123, Sweden
| | - K Schütze
- KWS SAAT SE, Grimsehlstraße 31, Einbeck 37555, Germany
| | - D Borchardt
- KWS SAAT SE, Grimsehlstraße 31, Einbeck 37555, Germany
| | - O Toerjek
- KWS SAAT SE, Grimsehlstraße 31, Einbeck 37555, Germany
| | - W Mechelke
- KWS SAAT SE, Grimsehlstraße 31, Einbeck 37555, Germany
| | - J C Lein
- KWS SAAT SE, Grimsehlstraße 31, Einbeck 37555, Germany
| | - A W Schechert
- Strube Research GmbH &Co. KG, Hauptstraße 1, Söllingen 38387, Germany
| | - L Frese
- Federal Research Centre for Cultivated Plants (JKI), Erwin-Baur-Str. 27, Quedlinburg 06484, Germany
| | - H Himmelbauer
- Max Planck Institute for Molecular Genetics, Ihnestraße 73, Berlin 14195, Germany.,Department of Biotechnology, University of Natural Resources and Life Sciences (BOKU), Muthgasse 18, 1190 Vienna, Austria.,Centre for Genomic Regulation (CRG), Carrer del Dr. Aiguader 88, Barcelona 08003, Spain
| | - B Weisshaar
- CeBiTec &Faculty of Biology, Bielefeld University, Universitätsstraße 25, Bielefeld 33615, Germany
| | - F J Kopisch-Obuch
- Plant Breeding Institute, Kiel University, Am Botanischen Garten 1-9, Kiel 24118, Germany.,KWS SAAT SE, Grimsehlstraße 31, Einbeck 37555, Germany
| |
Collapse
|
3
|
Tränkner C, Lemnian IM, Emrani N, Pfeiffer N, Tiwari SP, Kopisch-Obuch FJ, Vogt SH, Müller AE, Schilhabel M, Jung C, Grosse I. A Detailed Analysis of the BR1 Locus Suggests a New Mechanism for Bolting after Winter in Sugar Beet ( Beta vulgaris L.). Front Plant Sci 2016; 7:1662. [PMID: 27895650 PMCID: PMC5107561 DOI: 10.3389/fpls.2016.01662] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/21/2016] [Indexed: 05/29/2023]
Abstract
Sugar beet (Beta vulgaris ssp. vulgaris) is a biennial, sucrose-storing plant, which is mainly cultivated as a spring crop and harvested in the vegetative stage before winter. For increasing beet yield, over-winter cultivation would be advantageous. However, bolting is induced after winter and drastically reduces yield. Thus, post-winter bolting control is essential for winter beet cultivation. To identify genetic factors controlling bolting after winter, a F2 population was previously developed by crossing the sugar beet accessions BETA 1773 with reduced bolting tendency and 93161P with complete bolting after winter. For a mapping-by-sequencing analysis, pools of 26 bolting-resistant and 297 bolting F2 plants were used. Thereby, a single continuous homozygous region of 103 kb was co-localized to the previously published BR1 QTL for post-winter bolting resistance (Pfeiffer et al., 2014). The BR1 locus was narrowed down to 11 candidate genes from which a homolog of the Arabidopsis CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR 73-I (CPSF73-I) was identified as the most promising candidate. A 2 bp deletion within the BETA 1773 allele of BvCPSF73-Ia results in a truncated protein. However, the null allele of BvCPSF73-Ia might partially be compensated by a second BvCPSF73-Ib gene. This gene is located 954 bp upstream of BvCPSF73-Ia and could be responsible for the incomplete penetrance of the post-winter bolting resistance allele of BETA 1773. This result is an important milestone for breeding winter beets with complete bolting resistance after winter.
Collapse
Affiliation(s)
- Conny Tränkner
- Plant Breeding Institute, University of KielKiel, Germany
| | - Ioana M. Lemnian
- Institute of Computer Science, Martin Luther University Halle-WittenbergHalle, Germany
| | - Nazgol Emrani
- Plant Breeding Institute, University of KielKiel, Germany
| | - Nina Pfeiffer
- Plant Breeding Institute, University of KielKiel, Germany
| | | | | | | | | | - Markus Schilhabel
- Institute of Clinical Molecular Biology, University of KielKiel, Germany
| | - Christian Jung
- Plant Breeding Institute, University of KielKiel, Germany
| | - Ivo Grosse
- Institute of Computer Science, Martin Luther University Halle-WittenbergHalle, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Leipzig-JenaLeipzig, Germany
| |
Collapse
|
4
|
Pfeiffer N, Tränkner C, Lemnian I, Grosse I, Müller AE, Jung C, Kopisch-Obuch FJ. Genetic analysis of bolting after winter in sugar beet (Beta vulgaris L.). Theor Appl Genet 2014; 127:2479-89. [PMID: 25212110 DOI: 10.1007/s00122-014-2392-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 08/28/2014] [Indexed: 05/08/2023]
Abstract
This study reveals for the first time a major QTL for post-winter bolting resistance in sugar beet ( Beta vulgaris L.). The knowledge of this QTL is a major contribution towards the development of a winter sugar beet with controlled bolting behavior. In cool temperate climates, sugar beets are currently grown as a spring crop. They are sown in spring and harvested in autumn. Growing sugar beet as a winter crop with an extended vegetation period fails due to bolting after winter. Bolting after winter might be controlled by accumulating genes for post-winter bolting resistance. Previously, we had observed in field experiments a low post-winter bolting rate of 0.5 for sugar beet accession BETA 1773. This accession was crossed with a biennial sugar beet with regular bolting behavior to develop a F3 mapping population. The population was grown in the greenhouse, exposed to artificial cold treatment for 16 weeks and transplanted to the field. Bolting was recorded twice a week from May until October. Post-winter bolting behavior was assessed by two different factors, bolting delay (determined as days to bolt after cold treatment) and post-winter bolting resistance (bolting rate after winter). For days to bolt, means of F3 families ranged from 25 to 164 days while for bolting rate F3 families ranged from 0 to 1. For each factor one QTL explaining about 65% of the phenotypic variation was mapped to the same region on linkage group 9 with a partially recessive allele increasing bolting delay and post-winter bolting resistance. The results are discussed in relation to the potential use of marker-assisted breeding of winter sugar beets with controlled bolting.
Collapse
Affiliation(s)
- Nina Pfeiffer
- Plant Breeding Institute, Christian Albrechts University of Kiel, Olshausenstrasse 40, 24118, Kiel, Germany
| | | | | | | | | | | | | |
Collapse
|
5
|
Frerichmann SLM, Kirchhoff M, Müller AE, Scheidig AJ, Jung C, Kopisch-Obuch FJ. EcoTILLING in Beta vulgaris reveals polymorphisms in the FLC-like gene BvFL1 that are associated with annuality and winter hardiness. BMC Plant Biol 2013; 13:52. [PMID: 23531083 PMCID: PMC3636108 DOI: 10.1186/1471-2229-13-52] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [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: 09/12/2012] [Accepted: 02/21/2013] [Indexed: 05/21/2023]
Abstract
BACKGROUND Sugar beet (Beta vulgaris ssp. vulgaris L.) is an important crop for sugar and biomass production in temperate climate regions. Currently sugar beets are sown in spring and harvested in autumn. Autumn-sown sugar beets that are grown for a full year have been regarded as a cropping system to increase the productivity of sugar beet cultivation. However, for the development of these "winter beets" sufficient winter hardiness and a system for bolting control is needed. Both require a thorough understanding of the underlying genetics and its natural variation. RESULTS We screened a diversity panel of 268 B. vulgaris accessions for three flowering time genes via EcoTILLING. This panel had been tested in the field for bolting behaviour and winter hardiness. EcoTILLING identified 20 silent SNPs and one non-synonymous SNP within the genes BTC1, BvFL1 and BvFT1, resulting in 55 haplotypes. Further, we detected associations of nucleotide polymorphisms in BvFL1 with bolting before winter as well as winter hardiness. CONCLUSIONS These data provide the first genetic indication for the function of the FLC homolog BvFL1 in beet. Further, it demonstrates for the first time that EcoTILLING is a powerful method for exploring genetic diversity and allele mining in B. vulgaris.
Collapse
Affiliation(s)
- Sebastian LM Frerichmann
- Plant Breeding Institute, Christian-Albrechts-University of Kiel, Olshausenstr. 40, Kiel, 24098, Germany
| | - Martin Kirchhoff
- Plant Breeding Institute, Christian-Albrechts-University of Kiel, Olshausenstr. 40, Kiel, 24098, Germany
- Nordsaat Saatzucht GmbH, Böhnshauser Straße, Langenstein, 38895, Germany
| | - Andreas E Müller
- Plant Breeding Institute, Christian-Albrechts-University of Kiel, Olshausenstr. 40, Kiel, 24098, Germany
- Strube Research GmbH & Co. KG, Hauptstr. 1, Söllingen, 38387, Germany
| | - Axel J Scheidig
- Zoological Institute, Department of Structural Biology, Christian-Albrechts-University of Kiel, Am Botanischen Garten 1-9, Kiel, 24118, Germany
| | - Christian Jung
- Plant Breeding Institute, Christian-Albrechts-University of Kiel, Olshausenstr. 40, Kiel, 24098, Germany
| | - Friedrich J Kopisch-Obuch
- Plant Breeding Institute, Christian-Albrechts-University of Kiel, Olshausenstr. 40, Kiel, 24098, Germany
| |
Collapse
|
6
|
Fritsche S, Wang X, Li J, Stich B, Kopisch-Obuch FJ, Endrigkeit J, Leckband G, Dreyer F, Friedt W, Meng J, Jung C. A candidate gene-based association study of tocopherol content and composition in rapeseed (Brassica napus). Front Plant Sci 2012; 3:129. [PMID: 22740840 PMCID: PMC3382996 DOI: 10.3389/fpls.2012.00129] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 05/30/2012] [Indexed: 05/06/2023]
Abstract
Rapeseed (Brassica napus L.) is the most important oil crop of temperate climates. Rapeseed oil contains tocopherols, also known as vitamin E, which is an indispensable nutrient for humans and animals due to its antioxidant and radical scavenging abilities. Moreover, tocopherols are also important for the oxidative stability of vegetable oils. Therefore, seed oil with increased tocopherol content or altered tocopherol composition is a target for breeding. We investigated the role of nucleotide variations within candidate genes from the tocopherol biosynthesis pathway. Field trials were carried out with 229 accessions from a worldwide B. napus collection which was divided into two panels of 96 and 133 accessions. Seed tocopherol content and composition were measured by HPLC. High heritabilities were found for both traits, ranging from 0.62 to 0.94. We identified polymorphisms by sequencing selected regions of the tocopherol genes from the 96 accession panel. Subsequently, we determined the population structure (Q) and relative kinship (K) as detected by genotyping with genome-wide distributed SSR markers. Association studies were performed using two models, the structure-based GLM + Q and the PK-mixed model. Between 26 and 12 polymorphisms within two genes (BnaX.VTE3.a, BnaA.PDS1.c) were significantly associated with tocopherol traits. The SNPs explained up to 16.93% of the genetic variance for tocopherol composition and up to 10.48% for total tocopherol content. Based on the sequence information we designed CAPS markers for genotyping the 133 accessions from the second panel. Significant associations with various tocopherol traits confirmed the results from the first experiment. We demonstrate that the polymorphisms within the tocopherol genes clearly impact tocopherol content and composition in B. napus seeds. We suggest that these nucleotide variations may be used as selectable markers for breeding rapeseed with enhanced tocopherol quality.
Collapse
Affiliation(s)
- Steffi Fritsche
- Faculty of Agricultural and Nutritional Sciences, Plant Breeding Institute, Christian-Albrechts-UniversityKiel, Germany
| | - Xingxing Wang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural UniversityWuhan, China
| | - Jinquan Li
- Quantitative Crop Genetics, Max Planck Institute for Plant Breeding ResearchCologne, Germany
| | - Benjamin Stich
- Quantitative Crop Genetics, Max Planck Institute for Plant Breeding ResearchCologne, Germany
| | - Friedrich J. Kopisch-Obuch
- Faculty of Agricultural and Nutritional Sciences, Plant Breeding Institute, Christian-Albrechts-UniversityKiel, Germany
| | - Jessica Endrigkeit
- Faculty of Agricultural and Nutritional Sciences, Plant Breeding Institute, Christian-Albrechts-UniversityKiel, Germany
| | - Gunhild Leckband
- Norddeutsche Pflanzenzucht Hans-Georg Lembke KGHohenlieth, Germany
| | - Felix Dreyer
- Norddeutsche Pflanzenzucht Hans-Georg Lembke KGHohenlieth, Germany
| | - Wolfgang Friedt
- Faculty of Agricultural Sciences, Nutritional Sciences and Environmental Management, Institute of Agronomy and Plant Breeding I, Justus-Liebig-UniversityGiessen, Germany
| | - Jinling Meng
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural UniversityWuhan, China
| | - Christian Jung
- Faculty of Agricultural and Nutritional Sciences, Plant Breeding Institute, Christian-Albrechts-UniversityKiel, Germany
- *Correspondence: Christian Jung, Plant Breeding Institute, Christian-Albrechts-University, Olshausenstrasse 40, 24118 Kiel, Germany. e-mail:
| |
Collapse
|
7
|
Sharma S, Sharma S, Kopisch-Obuch FJ, Keil T, Laubach E, Stein N, Graner A, Jung C. QTL analysis of root-lesion nematode resistance in barley: 1. Pratylenchus neglectus. Theor Appl Genet 2011; 122:1321-30. [PMID: 21298411 DOI: 10.1007/s00122-011-1533-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 01/06/2011] [Indexed: 05/20/2023]
Abstract
The root-lesion nematode Pratylenchus neglectus can cause severe losses in barley cultivation. Multiplication rates had been found to vary greatly between different barley accessions. Two winter barley cultivars, Igri and Franka, had been found to differ in their ability to resist this parasite. An existing Igri × Franka doubled haploid population was chosen to genetically map resistance genes after artificial inoculation with P. neglectus in the greenhouse and climate chamber. A continuous phenotypic variation was found indicating a quantitative inheritance of P. neglectus resistance. An existing map was enriched by 527 newly developed Diversity Array Technology markers (DArTs). The new genetic linkage map was comprised of 857 molecular markers that cover 1,157 cM on seven linkage groups. Using phenotypic data collected from four different experiments in 3 years, five quantitative trait loci were mapped by composite interval mapping on four (3H, 5H, 6H and 7H) linkage groups. A quantitative trait locus with a large phenotypic effect of 16% and likelihood of odds (LOD) score of 6.35 was mapped on linkage group 3H. The remaining four QTLs were classified as minor or moderate with LOD scores ranging from 2.71 to 3.55 and R (2) values ranging from 8 to 10%. The DNA markers linked to the resistance QTLs should be quite useful for marker-assisted selection in barley breeding because phenotypic selection is limited due to time constraints and labor costs.
Collapse
Affiliation(s)
- Shiveta Sharma
- Plant Breeding Institute, Christian-Albrechts-University of Kiel, Olshausenstrasse 40, Kiel, Germany
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Ofori A, Becker HC, Kopisch-Obuch FJ. Effect of crop improvement on genetic diversity in oilseed Brassica rapa (turnip-rape) cultivars, detected by SSR markers. J Appl Genet 2008; 49:207-12. [PMID: 18670055 DOI: 10.1007/bf03195615] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
With the improvement of seed quality, Brassica rapa oilseed germplasm went through 2 major breeding bottlenecks during the introgression of genes for zero erucic acid content and low glucosinolate content, respectively. This study investigates the impact of these bottlenecks on the genetic diversity in European winter B. rapa by comparing 3 open-pollinated cultivars, each representing a different breeding period. Diversity was estimated on 32 plants per cultivar, with 16 simple sequence repeat (SSR) markers covering each of the B. rapa linkage groups. There was no significant loss of genetic diversity over the 3 cultivars as indicated by allele number (ranging from 59 to 55), mean allele number (from 3.68 to 3.50), Shannon information index (from 0.94 to 0.87) and expected heterozygosity (from 0.53 to 0.48). About 83% of the total variation was attributed to within-cultivar variation, and the remaining 17% to between-cultivar variation by analysis of molecular variance (AMOVA). Individual plants were separated into the 3 cultivars by principal coordinate analysis (PCoA). In conclusion, genetic diversity within cultivars was high and quality breeding in B. rapa did not significantly reduce the genetic diversity of B. rapa winter cultivars, so there is no risk of decline in performance due to quality improvement.
Collapse
Affiliation(s)
- Atta Ofori
- Department of Crop Sciences, Georg-August-University Göttingen, Von-Siebold-Str. 8, 37075, Göttingen, Germany.
| | | | | |
Collapse
|
9
|
Kopisch-Obuch FJ, Diers BW. Segregation at the SCN resistance locus rhg1 in soybean is distorted by an association between the resistance allele and reduced field emergence. Theor Appl Genet 2006; 112:199-207. [PMID: 16292671 DOI: 10.1007/s00122-005-0104-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 09/01/2005] [Indexed: 05/05/2023]
Abstract
Segregation distortion has been reported repeatedly in soybean (Glycine max [L.] Merr.) inbred line populations segregating for the soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) resistance gene rhg1. In each reported case, the frequency of the SCN resistance allele at the rhg1 locus was lower than expected. Segregation distortion was studied in 51 F4 populations by counting the number of plants predicted to be homozygous resistant, susceptible, and heterozygous for rhg1 based on the genetic markers Satt309, CTA, or TMA5. Significant (P<0.05) segregation distortion was observed in 44 out of the 51 F4 populations. When the heterozygotes were ignored, there were significantly fewer homozygous-resistant plants than expected in 33 populations. To study whether differential field emergence was a cause of the segregation distortion, three near isogenic line (NIL) populations segregating at the rhg1 locus for SCN resistance from plant introduction 88788 were tested. Population sizes ranged from 32 to 44 NILs and emergence was determined in field experiments in three environments. In each population, SCN-resistant NILs had significantly (P<0.05) less field emergence than susceptible NILs. In the population with the greatest effect, field emergence of resistant NILs was 6% less than susceptible NILs, with the entire population having an average emergence rate of 46%. Equations were derived to describe the effect of selection on segregation ratios over generations of population development and the observed emergence rates were transformed into fitness factors. Depending on assumptions of gene action, it was predicted from these fitness factors that segregation distortions were in the range of those reported previously for the rhg1 locus and were similar to what was observed on average across the 51 F4 populations. While other factors might also be involved, the results suggest that reduced field emergence associated with the SCN resistance allele contributes to previously reported segregation distortion at the rhg1 locus.
Collapse
Affiliation(s)
- F J Kopisch-Obuch
- Institute of Agronomy and Plant Breeding, Georg-August-University, Von-Siebold-Str. 8, 37075 Göttingen, Germany
| | | |
Collapse
|