1
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Laforest M, Martin SL, Bisaillon K, Soufiane B, Meloche S, Tardif FJ, Page E. The ancestral karyotype of the Heliantheae Alliance, herbicide resistance, and human allergens: Insights from the genomes of common and giant ragweed. THE PLANT GENOME 2024; 17:e20442. [PMID: 38481294 DOI: 10.1002/tpg2.20442] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 01/23/2024] [Accepted: 02/04/2024] [Indexed: 07/02/2024]
Abstract
Ambrosia artemisiifolia and Ambrosia trifida (Asteraceae) are important pest species and the two greatest sources of aeroallergens globally. Here, we took advantage of a hybrid to simplify genome assembly and present chromosome-level assemblies for both species. These assemblies show high levels of completeness with Benchmarking Universal Single-Copy Ortholog (BUSCO) scores of 94.5% for A. artemisiifolia and 96.1% for A. trifida and long terminal repeat (LTR) Assembly Index values of 26.6 and 23.6, respectively. The genomes were annotated using RNA data identifying 41,642 genes in A. artemisiifolia and 50,203 in A. trifida. More than half of the genome is composed of repetitive elements, with 62% in A. artemisiifolia and 69% in A. trifida. Single copies of herbicide resistance-associated genes PPX2L, HPPD, and ALS were found, while two copies of the EPSPS gene were identified; this latter observation may reveal a possible mechanism of resistance to the herbicide glyphosate. Ten of the 12 main allergenicity genes were also localized, some forming clusters with several copies, especially in A. artemisiifolia. The evolution of genome structure has differed among these two species. The genome of A. trifida has undergone greater rearrangement, possibly the result of chromoplexy. In contrast, the genome of A. artemisiifolia retains a structure that makes the allotetraploidization of the most recent common ancestor of the Heliantheae Alliance the clearest feature of its genome. When compared to other Heliantheae Alliance species, this allowed us to reconstruct the common ancestor's karyotype-a key step for furthering of our understanding of the evolution and diversification of this economically and allergenically important group.
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Affiliation(s)
- Martin Laforest
- Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, Quebec, Canada
| | - Sara L Martin
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada
| | - Katherine Bisaillon
- Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, Quebec, Canada
| | - Brahim Soufiane
- Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, Quebec, Canada
| | - Sydney Meloche
- Harrow Research and Development Centre, Agriculture and Agri-Food Canada, Harrow, Ontario, Canada
| | - François J Tardif
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada
| | - Eric Page
- Harrow Research and Development Centre, Agriculture and Agri-Food Canada, Harrow, Ontario, Canada
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2
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Wang S, Wang A, Chen R, Xu D, Wang H, Jiang F, Liu H, Qian W, Fan W. Haplotype-resolved chromosome-level genome of hexaploid Jerusalem artichoke provides insights into its origin, evolution, and inulin metabolism. PLANT COMMUNICATIONS 2024; 5:100767. [PMID: 37974403 PMCID: PMC10943552 DOI: 10.1016/j.xplc.2023.100767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/12/2023] [Accepted: 11/14/2023] [Indexed: 11/19/2023]
Abstract
Jerusalem artichoke (Helianthus tuberosus) is a global multifunctional crop. It has wide applications in the food, health, feed, and biofuel industries and in ecological protection; it also serves as a germplasm pool for breeding of the global oil crop common sunflower (Helianthus annuus). However, biological studies of Jerusalem artichoke have been hindered by a lack of genome sequences, and its high polyploidy and large genome size have posed challenges to genome assembly. Here, we report a 21-Gb chromosome-level assembly of the hexaploid Jerusalem artichoke genome, which comprises 17 homologous groups, each with 6 pseudochromosomes. We found multiple large-scale chromosome rearrangements between Jerusalem artichoke and common sunflower, and our results show that the hexaploid genome of Jerusalem artichoke was formed by a hybridization event between a tetraploid and a diploid Helianthus species, followed by chromosome doubling of the hybrid, which occurred approximately 2 million years ago. Moreover, we identified more copies of actively expressed genes involved in inulin metabolism and showed that these genes may still be undergoing loss of function or sub- or neofunctionalization. These genomic resources will promote further biological studies, breeding improvement, and industrial utilization of Helianthus crops.
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Affiliation(s)
- Sen Wang
- Guangdong Laboratory for Lingnan Modern Agriculture (Shenzhen Branch), Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China; Guangdong Provincial Key Laboratory for Crop Germplasm Resources Preservation and Utilization, Agro-Biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
| | - Anqi Wang
- Guangdong Laboratory for Lingnan Modern Agriculture (Shenzhen Branch), Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
| | - Rong Chen
- Guangdong Laboratory for Lingnan Modern Agriculture (Shenzhen Branch), Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China; College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China
| | - Dong Xu
- Guangdong Laboratory for Lingnan Modern Agriculture (Shenzhen Branch), Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
| | - Hengchao Wang
- Guangdong Laboratory for Lingnan Modern Agriculture (Shenzhen Branch), Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
| | - Fan Jiang
- Guangdong Laboratory for Lingnan Modern Agriculture (Shenzhen Branch), Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
| | - Hangwei Liu
- Guangdong Laboratory for Lingnan Modern Agriculture (Shenzhen Branch), Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
| | - Wanqiang Qian
- Guangdong Laboratory for Lingnan Modern Agriculture (Shenzhen Branch), Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China
| | - Wei Fan
- Guangdong Laboratory for Lingnan Modern Agriculture (Shenzhen Branch), Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangdong 518120, China.
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3
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Ostevik KL, Alabady M, Zhang M, Rausher MD. Whole-genome sequence and annotation of Penstemon davidsonii. G3 (BETHESDA, MD.) 2024; 14:jkad296. [PMID: 38155402 PMCID: PMC10917496 DOI: 10.1093/g3journal/jkad296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/30/2023] [Accepted: 12/01/2023] [Indexed: 12/30/2023]
Abstract
Penstemon is the most speciose flowering plant genus endemic to North America. Penstemon species' diverse morphology and adaptation to various environments have made them a valuable model system for studying evolution. Here, we report the first full reference genome assembly and annotation for Penstemon davidsonii. Using PacBio long-read sequencing and Hi-C scaffolding technology, we constructed a de novo reference genome of 437,568,744 bases, with a contig N50 of 40 Mb and L50 of 5. The annotation includes 18,199 gene models, and both the genome and transcriptome assembly contain over 95% complete eudicot BUSCOs. This genome assembly will serve as a valuable reference for studying the evolutionary history and genetic diversity of the Penstemon genus.
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Affiliation(s)
- Kate L Ostevik
- Department of Evolution, Ecology, and Organismal Biology, University of California Riverside, Riverside, CA 92521, USA
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Magdy Alabady
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
| | - Mengrui Zhang
- Department of Statistics, University of Georgia, Athens, GA 30602, USA
| | - Mark D Rausher
- Department of Biology, Duke University, Durham, NC 27708, USA
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4
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Fernández-Melero B, Del Moral L, Todesco M, Rieseberg LH, Owens GL, Carrère S, Chabaud M, Muños S, Velasco L, Pérez-Vich B. Development and characterization of a new sunflower source of resistance to race G of Orobanche cumana Wallr. derived from Helianthus anomalus. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2024; 137:56. [PMID: 38386181 PMCID: PMC10884359 DOI: 10.1007/s00122-024-04558-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/20/2024] [Indexed: 02/23/2024]
Abstract
KEY MESSAGE A new OrAnom1 gene introgressed in cultivated sunflower from wild Helianthus anomalus confers late post-attachment resistance to Orobanche cumana race G and maps to a target interval in Chromosome 4 where two receptor-like kinases (RLKs) have been identified in the H. anomalus genome as putative candidates. Sunflower broomrape is a parasitic weed that infects sunflower (Helianthus annuus L.) roots causing severe yield losses. Breeding for resistance is the most effective and sustainable control method. In this study, we report the identification, introgression, and genetic and physiological characterization of a new sunflower source of resistance to race G of broomrape developed from the wild annual sunflower H. anomalus (accession PI 468642). Crosses between PI 468642 and the susceptible line P21 were carried out, and the genetic study was conducted in BC1F1, BC1F2, and its derived BC1F3 populations. A BC1F5 germplasm named ANOM1 was developed through selection for race G resistance and resemblance to cultivated sunflower. The resistant trait showed monogenic and dominant inheritance. The gene, named OrAnom1, was mapped to Chromosome 4 within a 1.2 cM interval and co-segregated with 7 SNP markers. This interval corresponds to a 1.32 Mb region in the sunflower reference genome, housing a cluster of receptor-like kinase and receptor-like protein (RLK-RLP) genes. Notably, the analysis of the H. anomalus genome revealed the absence of RLPs in the OrAnom1 target region but featured two RLKs as possible OrAnom1 candidates. Rhizotron and histological studies showed that OrAnom1 determines a late post-attachment resistance mechanism. Broomrape can establish a vascular connection with the host, but parasite growth is stopped before tubercle development, showing phenolic compounds accumulation and tubercle necrosis. ANOM1 will contribute to broadening the genetic basis of broomrape resistance in the cultivated sunflower pool and to a better understanding of the molecular basis of the sunflower-broomrape interaction.
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Affiliation(s)
- Belén Fernández-Melero
- Instituto de Agricultura Sostenible (IAS-CSIC), Alameda del Obispo S/N, 14004, Córdoba, Spain
| | - Lidia Del Moral
- Instituto de Agricultura Sostenible (IAS-CSIC), Alameda del Obispo S/N, 14004, Córdoba, Spain
| | - Marco Todesco
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Biodiversity Research Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Loren H Rieseberg
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Biodiversity Research Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Gregory L Owens
- Department of Biology, University of Victoria, Victoria, BC, V8W 2Y2, Canada
| | - Sébastien Carrère
- Laboratoire des Interactions Plantes Microbes-Environnement (LIPME), Université de Toulouse, CNRS, INRAE, Castanet-Tolosan, France
| | - Mireille Chabaud
- Laboratoire des Interactions Plantes Microbes-Environnement (LIPME), Université de Toulouse, CNRS, INRAE, Castanet-Tolosan, France
| | - Stéphane Muños
- Laboratoire des Interactions Plantes Microbes-Environnement (LIPME), Université de Toulouse, CNRS, INRAE, Castanet-Tolosan, France
| | - Leonardo Velasco
- Instituto de Agricultura Sostenible (IAS-CSIC), Alameda del Obispo S/N, 14004, Córdoba, Spain
| | - Begoña Pérez-Vich
- Instituto de Agricultura Sostenible (IAS-CSIC), Alameda del Obispo S/N, 14004, Córdoba, Spain.
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5
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Sotola VA, Berg CS, Samuli M, Chen H, Mantel SJ, Beardsley PA, Yuan YW, Sweigart AL, Fishman L. Genomic mechanisms and consequences of diverse postzygotic barriers between monkeyflower species. Genetics 2023; 225:iyad156. [PMID: 37603838 DOI: 10.1093/genetics/iyad156] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/15/2023] [Accepted: 07/18/2023] [Indexed: 08/23/2023] Open
Abstract
The evolution of genomic incompatibilities causing postzygotic barriers to hybridization is a key step in species divergence. Incompatibilities take 2 general forms-structural divergence between chromosomes leading to severe hybrid sterility in F1 hybrids and epistatic interactions between genes causing reduced fitness of hybrid gametes or zygotes (Dobzhansky-Muller incompatibilities). Despite substantial recent progress in understanding the molecular mechanisms and evolutionary origins of both types of incompatibility, how each behaves across multiple generations of hybridization remains relatively unexplored. Here, we use genetic mapping in F2 and recombinant inbred line (RIL) hybrid populations between the phenotypically divergent but naturally hybridizing monkeyflowers Mimulus cardinalis and M. parishii to characterize the genetic basis of hybrid incompatibility and examine its changing effects over multiple generations of experimental hybridization. In F2s, we found severe hybrid pollen inviability (<50% reduction vs parental genotypes) and pseudolinkage caused by a reciprocal translocation between Chromosomes 6 and 7 in the parental species. RILs retained excess heterozygosity around the translocation breakpoints, which caused substantial pollen inviability when interstitial crossovers had not created compatible heterokaryotypic configurations. Strong transmission ratio distortion and interchromosomal linkage disequilibrium in both F2s and RILs identified a novel 2-locus genic incompatibility causing sex-independent gametophytic (haploid) lethality. The latter interaction eliminated 3 of the expected 9 F2 genotypic classes via F1 gamete loss without detectable effects on the pollen number or viability of F2 double heterozygotes. Along with the mapping of numerous milder incompatibilities, these key findings illuminate the complex genetics of plant hybrid breakdown and are an important step toward understanding the genomic consequences of natural hybridization in this model system.
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Affiliation(s)
- V Alex Sotola
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Colette S Berg
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Matthew Samuli
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Hongfei Chen
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Samuel J Mantel
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Paul A Beardsley
- Department of Biological Sciences, California State Polytechnic University, Pomona, CA 91768, USA
| | - Yao-Wu Yuan
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Andrea L Sweigart
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Lila Fishman
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
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6
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Bock DG, Cai Z, Elphinstone C, González-Segovia E, Hirabayashi K, Huang K, Keais GL, Kim A, Owens GL, Rieseberg LH. Genomics of plant speciation. PLANT COMMUNICATIONS 2023; 4:100599. [PMID: 37050879 PMCID: PMC10504567 DOI: 10.1016/j.xplc.2023.100599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/21/2023] [Accepted: 04/06/2023] [Indexed: 06/19/2023]
Abstract
Studies of plants have been instrumental for revealing how new species originate. For several decades, botanical research has complemented and, in some cases, challenged concepts on speciation developed via the study of other organisms while also revealing additional ways in which species can form. Now, the ability to sequence genomes at an unprecedented pace and scale has allowed biologists to settle decades-long debates and tackle other emerging challenges in speciation research. Here, we review these recent genome-enabled developments in plant speciation. We discuss complications related to identification of reproductive isolation (RI) loci using analyses of the landscape of genomic divergence and highlight the important role that structural variants have in speciation, as increasingly revealed by new sequencing technologies. Further, we review how genomics has advanced what we know of some routes to new species formation, like hybridization or whole-genome duplication, while casting doubt on others, like population bottlenecks and genetic drift. While genomics can fast-track identification of genes and mutations that confer RI, we emphasize that follow-up molecular and field experiments remain critical. Nonetheless, genomics has clarified the outsized role of ancient variants rather than new mutations, particularly early during speciation. We conclude by highlighting promising avenues of future study. These include expanding what we know so far about the role of epigenetic and structural changes during speciation, broadening the scope and taxonomic breadth of plant speciation genomics studies, and synthesizing information from extensive genomic data that have already been generated by the plant speciation community.
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Affiliation(s)
- Dan G Bock
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Zhe Cai
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Cassandra Elphinstone
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Eric González-Segovia
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | | | - Kaichi Huang
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Graeme L Keais
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Amy Kim
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Gregory L Owens
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.
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7
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Pazhenkova EA, Lukhtanov VA. Chromosomal conservatism vs chromosomal megaevolution: enigma of karyotypic evolution in Lepidoptera. Chromosome Res 2023; 31:16. [PMID: 37300756 DOI: 10.1007/s10577-023-09725-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 05/21/2023] [Accepted: 05/23/2023] [Indexed: 06/12/2023]
Abstract
In the evolution of many organisms, periods of slow genome reorganization (= chromosomal conservatism) are interrupted by bursts of numerous chromosomal changes (= chromosomal megaevolution). Using comparative analysis of chromosome-level genome assemblies, we investigated these processes in blue butterflies (Lycaenidae). We demonstrate that the phase of chromosome number conservatism is characterized by the stability of most autosomes and dynamic evolution of the sex chromosome Z, resulting in multiple variants of NeoZ chromosomes due to autosome-sex chromosome fusions. In contrast during the phase of rapid chromosomal evolution, the explosive increase in chromosome number occurs mainly through simple chromosomal fissions. We show that chromosomal megaevolution is a highly non-random canalized process, and in two phylogenetically independent Lysandra lineages, the drastic parallel increase in number of fragmented chromosomes was achieved, at least partially, through reuse of the same ancestral chromosomal breakpoints. In species showing chromosome number doubling, we found no blocks of duplicated sequences or duplicated chromosomes, thus refuting the hypothesis of polyploidy. In the studied taxa, long blocks of interstitial telomere sequences (ITSs) consist of (TTAGG)n arrays interspersed with telomere-specific retrotransposons. ITSs are sporadically present in rapidly evolving Lysandra karyotypes, but not in the species with ancestral chromosome number. Therefore, we hypothesize that the transposition of telomeric sequences may be triggers of the rapid chromosome number increase. Finally, we discuss the hypothetical genomic and population mechanisms of chromosomal megaevolution and argue that the disproportionally high evolutionary role of the Z sex chromosome can be additionally reinforced by sex chromosome-autosome fusions and Z-chromosome inversions.
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Affiliation(s)
- Elena A Pazhenkova
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna Pot 111, 1000, Ljubljana, Slovenia.
| | - Vladimir A Lukhtanov
- Department of Karyosystematics, Zoological Institute of Russian Academy of Sciences, Universitetskaya Nab. 1, 199034, St. Petersburg, Russia.
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8
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Makarenko MS, Azarin KV, Gavrilova VA. Mitogenomic Research of Silverleaf Sunflower ( Helianthus argophyllus) and Its Interspecific Hybrids. Curr Issues Mol Biol 2023; 45:4841-4849. [PMID: 37367057 DOI: 10.3390/cimb45060308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/28/2023] [Accepted: 05/30/2023] [Indexed: 06/28/2023] Open
Abstract
Interspecific hybridization is widespread for sunflowers, both in wild populations and commercial breeding. One of the most common species that can efficiently cross with Helianthus annuus is the Silverleaf sunflower-Helianthus argophyllus. The current study carried out structural and functional organization analyses of mitochondrial DNA in H. argophyllus and the interspecific hybrid, H. annuus (VIR114A line) × H. argophyllus. The complete mitogenome of H. argophyllus counts 300,843 bp, has a similar organization to the mitogenome of cultivated sunflower, and holds SNPs typical for wild sunflowers. RNA editing analysis predicted 484 sites in H. argophyllus mitochondrial CDS. The mitochondrial genome of the H. annuus × H. argophyllus hybrid is identical to the maternal line (VIR114A). We expected that significant rearrangements in the mitochondrial DNA of the hybrid would occur, due to the frequent recombination. However, the hybrid mitogenome lacks rearrangements, presumably due to the preservation of nuclear-cytoplasmic interaction paths.
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Affiliation(s)
- Maksim S Makarenko
- The Laboratory of Plant Genomics, The Institute for Information Transmission Problems, 127051 Moscow, Russia
| | - Kirill V Azarin
- The Laboratory of Molecular Genetics, Southern Federal University, 344006 Rostov-on-Don, Russia
| | - Vera A Gavrilova
- Oil and Fiber Crops Genetic Resources Department, The N.I. Vavilov All Russian Institute of Plant Genetic Resources, 190031 Saint Petersburg, Russia
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9
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Makarenko MS, Gavrilova VA. NGS Reads Dataset of Sunflower Interspecific Hybrids. DATA 2023. [DOI: 10.3390/data8040067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023] Open
Abstract
The sunflower (Helianthus annuus), which belongs to the family of Asteraceae, is a crop grown worldwide for consumption by humans and livestock. Interspecific hybridization is widespread for sunflowers both in wild populations and commercial breeding. The current dataset comprises 250 bp and 76 paired-end NGS reads for six interspecific sunflower hybrids (F1). The dataset aimed to expand Helianthus species genomic information and benefit genetic research, and is useful in alloploids’ features investigations and nuclear–organelle interactions studies. Mitochondrial genomes of perennial sunflower hybrids H. annuus × H. strumosus and H. annuus × H. occidentalis were assembled and compared with parental forms.
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10
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Owens GL, Huang K, Todesco M, Rieseberg LH. Re-evaluating Homoploid Reticulate Evolution in Helianthus Sunflowers. Mol Biol Evol 2023; 40:6989481. [PMID: 36648104 PMCID: PMC9907532 DOI: 10.1093/molbev/msad013] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 01/03/2023] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
Sunflowers of the genus Helianthus are models for hybridization research and contain three of the best-studied examples of homoploid hybrid speciation. To understand a broader picture of hybridization within the annual sunflowers, we used whole-genome resequencing to conduct a phylogenomic analysis and test for gene flow between lineages. We find that all annual sunflower species tested have evidence of admixture, suggesting hybridization was common during the radiation of the genus. Support for the major species tree decreases with increasing recombination rate, consistent with hybridization and introgression contributing to discordant topologies. Admixture graphs found hybridization to be associated with the origins of the three putative hybrid species (Helianthus anomalus, Helianthus deserticola, and Helianthus paradoxus). However, the hybridization events are more ancient than suggested by previous work. Furthermore, H. anomalus and H. deserticola appear to have arisen from a single hybridization event involving an unexpected donor, rather than through multiple independent events as previously proposed. This means our results are consistent with, but not definitive proof of, two ancient independent homoploid hybrid speciation events in the genus. Using a broader data set that covers the whole Helianthus genus, including perennial species, we find that signals of introgression span the genus and beyond, suggesting highly divergent introgression and/or the sorting of ancient haplotypes. Thus, Helianthus can be viewed as a syngameon in which largely reproductively isolated species are linked together by occasional or frequent gene flow.
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Affiliation(s)
| | - Kaichi Huang
- Department of Botany and Beaty Biodiversity Center, University of British Columbia, Vancouver, BC, Canada
| | - Marco Todesco
- Department of Botany and Beaty Biodiversity Center, University of British Columbia, Vancouver, BC, Canada
| | - Loren H Rieseberg
- Department of Botany and Beaty Biodiversity Center, University of British Columbia, Vancouver, BC, Canada
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11
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Huang K, Ostevik KL, Elphinstone C, Todesco M, Bercovich N, Owens GL, Rieseberg LH. Mutation load in sunflower inversions is negatively correlated with inversion heterozygosity. Mol Biol Evol 2022; 39:6583099. [PMID: 35535689 PMCID: PMC9127631 DOI: 10.1093/molbev/msac101] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recombination is critical both for accelerating adaptation and purging deleterious mutations. Chromosomal inversions can act as recombination modifiers that suppress local recombination in heterozygotes and thus, under some conditions, are predicted to accumulate such mutations. In this study, we investigated patterns of recombination, transposable element abundance and coding sequence evolution across the genomes of 1,445 individuals from three sunflower species, as well as within nine inversions segregating within species. We also analyzed the effects of inversion genotypes on 87 phenotypic traits to test for overdominance. We found significant negative correlations of long terminal repeat retrotransposon abundance and deleterious mutations with recombination rates across the genome in all three species. However, we failed to detect an increase in these features in the inversions, except for a modest increase in the proportion of stop codon mutations in several very large or rare inversions. Consistent with this finding, there was little evidence of overdominance of inversions in phenotypes that may relate to fitness. On the other hand, significantly greater load was observed for inversions in populations polymorphic for a given inversion compared to populations monomorphic for one of the arrangements, suggesting that the local state of inversion polymorphism affects deleterious load. These seemingly contradictory results can be explained by the low frequency of inversion heterozygotes in wild sunflower populations, apparently due to divergent selection and associated geographic structure. Inversions contributing to local adaptation represent ideal recombination modifiers, acting to facilitate adaptive divergence with gene flow, while largely escaping the accumulation of deleterious mutations.
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Affiliation(s)
- Kaichi Huang
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Kate L Ostevik
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.,Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
| | - Cassandra Elphinstone
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Marco Todesco
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Natalia Bercovich
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Gregory L Owens
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.,Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
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12
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Development of first linkage map for Silphium integrifolium (Asteraceae) enables identification of sporophytic self-incompatibility locus. Heredity (Edinb) 2022; 128:304-312. [PMID: 35437327 PMCID: PMC9076636 DOI: 10.1038/s41437-022-00530-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 11/08/2022] Open
Abstract
Silphium integrifolium (Asteraceae) has been identified as a candidate for domestication as a perennial oilseed crop and is assumed to have sporophytic self-incompatibility system-the genetic basis of which is not well understood in the Asteraceae. To address this gap, we sought to map the genomic location of the self-recognition locus (S-locus) in this species. We used a biparental population and genotyping-by-sequencing to create the first genetic linkage map for this species, which contained 198 SNP markers and resolved into the correct number of linkage groups. Then we developed a novel crossing scheme and set of analysis methods in order to infer S-locus genotypes for a subset of these individuals, allowing us to map the trait. Finally, we evaluated potential genes of interest using synteny analysis with the annual sunflower (Helianthus annuus) and lettuce (Lactuca sativa) genomes. Our results confirm that S. integrifolium does indeed have a sporophytic self-incompatibility system. Our method is effective and efficient, allowed us to map the S. integrifolium S-locus using fewer resources than existing methods, and could be readily applied to other species.
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13
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14
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Bayat S, Lysak MA, Mandáková T. Genome structure and evolution in the cruciferous tribe Thlaspideae (Brassicaceae). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:1768-1785. [PMID: 34661331 DOI: 10.1111/tpj.15542] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 09/30/2021] [Accepted: 10/11/2021] [Indexed: 06/13/2023]
Abstract
Whole-genome duplications (WGDs) and chromosome rearrangements (CRs) play the key role in driving the diversification and evolution of plant lineages. Although the direct link between WGDs and plant diversification is well documented, relatively few studies focus on the evolutionary significance of CRs. The cruciferous tribe Thlaspideae represents an ideal model system to address the role of large-scale chromosome alterations in genome evolution, as most Thlaspideae species share the same diploid chromosome number (2n = 2x = 14). Here we constructed the genome structure in 12 Thlaspideae species, including field pennycress (Thlaspi arvense) and garlic mustard (Alliaria petiolata). We detected and precisely characterized genus- and species-specific CRs, mostly pericentric inversions, as the main genome-diversifying drivers in the tribe. We reconstructed the structure of seven chromosomes of an ancestral Thlaspideae genome, identified evolutionary stable chromosomes versus chromosomes prone to CRs, estimated the rate of CRs, and uncovered an allohexaploid origin of garlic mustard from diploid taxa closely related to A. petiolata and Parlatoria cakiloidea. Furthermore, we performed detailed bioinformatic analysis of the Thlaspideae repeatomes, and identified repetitive elements applicable as unique species- and genus-specific barcodes and chromosome landmarks. This study deepens our general understanding of the evolutionary role of CRs, particularly pericentric inversions, in plant genome diversification, and provides a robust base for follow-up whole-genome sequencing efforts.
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Affiliation(s)
- Soheila Bayat
- CEITEC, Masaryk University, Brno, 62500, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, 62500, Czech Republic
| | - Martin A Lysak
- CEITEC, Masaryk University, Brno, 62500, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, 62500, Czech Republic
| | - Terezie Mandáková
- CEITEC, Masaryk University, Brno, 62500, Czech Republic
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, 62500, Czech Republic
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15
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Makarenko MS, Omelchenko DO, Usatov AV, Gavrilova VA. The Insights into Mitochondrial Genomes of Sunflowers. PLANTS (BASEL, SWITZERLAND) 2021; 10:1774. [PMID: 34579307 PMCID: PMC8466785 DOI: 10.3390/plants10091774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/13/2021] [Accepted: 08/20/2021] [Indexed: 12/24/2022]
Abstract
The significant difference in the mtDNA size and structure with simultaneous slow evolving genes makes the mitochondrial genome paradoxical among all three DNA carriers in the plant cell. Such features make mitochondrial genome investigations of particular interest. The genus Helianthus is a diverse taxonomic group, including at least two economically valuable species-common sunflower (H. annuus) and Jerusalem artichoke (H. tuberosus). The successful investigation of the sunflower nuclear genome provided insights into some genomics aspects and significantly intensified sunflower genetic studies. However, the investigations of organelles' genetic information in Helianthus, especially devoted to mitochondrial genomics, are presented by limited studies. Using NGS sequencing, we assembled the complete mitochondrial genomes for H. occidentalis (281,175 bp) and H. tuberosus (281,287 bp) in the current investigation. Besides the master circle chromosome, in the case of H. tuberosus, the 1361 bp circular plasmid was identified. The mitochondrial gene content was found to be identical for both sunflower species, counting 32 protein-coding genes, 3 rRNA, 23 tRNA genes, and 18 ORFs. The comparative analysis between perennial sunflowers revealed common and polymorphic SSR and SNPs. Comparison of perennial sunflowers with H. annuus allowed us to establish similar rearrangements in mitogenomes, which have possibly been inherited from a common ancestor after the divergence of annual and perennial sunflower species. It is notable that H. occidentalis and H. tuberosus mitogenomes are much more similar to H. strumosus than H. grosseserratus.
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Affiliation(s)
- Maksim S. Makarenko
- The Laboratory of Plant Genomics, The Institute for Information Transmission Problems, 127051 Moscow, Russia;
| | - Denis O. Omelchenko
- The Laboratory of Plant Genomics, The Institute for Information Transmission Problems, 127051 Moscow, Russia;
| | - Alexander V. Usatov
- The Department of Genetics, Southern Federal University, 344006 Rostov-on-Don, Russia;
| | - Vera A. Gavrilova
- Oil and Fiber Crops Genetic Resources Department, The N.I. Vavilov All-Russian Institute of Plant Genetic Resources, 190031 Saint Petersburg, Russia;
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16
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Owens GL, Todesco M, Bercovich N, Légaré JS, Mitchell N, Whitney KD, Rieseberg LH. Standing variation rather than recent adaptive introgression probably underlies differentiation of the texanus subspecies of Helianthus annuus. Mol Ecol 2021; 30:6229-6245. [PMID: 34080243 DOI: 10.1111/mec.16008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 05/17/2021] [Accepted: 05/26/2021] [Indexed: 12/24/2022]
Abstract
The origins of geographic races in wide-ranging species are poorly understood. In Texas, the texanus subspecies of Helianthus annuus has long been thought to have acquired its defining phenotypic traits via introgression from a local congener, H. debilis, but previous tests of this hypothesis were inconclusive. Here, we explore the origins of H. a. texanus using whole genome sequencing data from across the entire range of H. annuus and possible donor species, as well as phenotypic data from a common garden study. We found that although it is morphologically convergent with H. debilis, H. a. texanus has conflicting signals of introgression. Genome wide tests (Patterson's D and TreeMix) only found evidence of introgression from H. argophyllus (sister species to H. annuus and also sympatric), but not H. debilis, with the exception of one individual of 109 analysed. We further scanned the genome for localized signals of introgression using PCAdmix and found minimal but nonzero introgression from H. debilis and significant introgression from H. argophyllus in some populations. Given the paucity of introgression from H. debilis, we argue that the morphological convergence observed in Texas is probably from standing genetic variation. We also found that genomic differentiation in H. a. texanus is mostly driven by large segregating inversions, several of which have signatures of natural selection based on haplotype frequencies.
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Affiliation(s)
- Gregory L Owens
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Marco Todesco
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Natalia Bercovich
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Jean-Sébastien Légaré
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Nora Mitchell
- Department of Biology, University of Wisconsin - Eau Claire, Eau Claire, WI, USA.,Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Kenneth D Whitney
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
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17
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Turner KG, Ostevik KL, Grassa CJ, Rieseberg LH. Genomic Analyses of Phenotypic Differences Between Native and Invasive Populations of Diffuse Knapweed (Centaurea diffusa). Front Ecol Evol 2021. [DOI: 10.3389/fevo.2020.577635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Invasive species represent excellent opportunities to study the evolutionary potential of traits important to success in novel environments. Although some ecologically important traits have been identified in invasive species, little is typically known about the genetic mechanisms that underlie invasion success in non-model species. Here, we use a genome-wide association (GWAS) approach to identify the genetic basis of trait variation in the non-model, invasive, diffuse knapweed [Centaurea diffusa Lam. (Asteraceae)]. To assist with this analysis, we have assembled the first draft genome reference and fully annotated plastome assembly for this species, and one of the first from this large, weedy, genus, which is of major ecological and economic importance. We collected phenotype data from 372 individuals from four native and four invasive populations of C. diffusa grown in a common environment. Using these individuals, we produced reduced-representation genotype-by-sequencing (GBS) libraries and identified 7,058 SNPs. We identify two SNPs associated with leaf width in these populations, a trait which significantly varies between native and invasive populations. In this rosette forming species, increased leaf width is a major component of increased biomass, a common trait in invasive plants correlated with increased fitness. Finally, we use annotations from Arabidopsis thaliana to identify 98 candidate genes that are near the associated SNPs and highlight several good candidates for leaf width variation.
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18
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Martin G, Baurens F, Hervouet C, Salmon F, Delos J, Labadie K, Perdereau A, Mournet P, Blois L, Dupouy M, Carreel F, Ricci S, Lemainque A, Yahiaoui N, D’Hont A. Chromosome reciprocal translocations have accompanied subspecies evolution in bananas. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 104:1698-1711. [PMID: 33067829 PMCID: PMC7839431 DOI: 10.1111/tpj.15031] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 10/02/2020] [Indexed: 05/09/2023]
Abstract
Chromosome rearrangements and the way that they impact genetic differentiation and speciation have long raised questions from evolutionary biologists. They are also a major concern for breeders because of their bearing on chromosome recombination. Banana is a major crop that derives from inter(sub)specific hybridizations between various once geographically isolated Musa species and subspecies. We sequenced 155 accessions, including banana cultivars and representatives of Musa diversity, and genotyped-by-sequencing 1059 individuals from 11 progenies. We precisely characterized six large reciprocal translocations and showed that they emerged in different (sub)species of Musa acuminata, the main contributor to currently cultivated bananas. Most diploid and triploid cultivars analyzed were structurally heterozygous for 1 to 4 M. acuminata translocations, highlighting their complex origin. We showed that all translocations induced a recombination reduction of variable intensity and extent depending on the translocations, involving only the breakpoint regions, a chromosome arm, or an entire chromosome. The translocated chromosomes were found preferentially transmitted in many cases. We explore and discuss the possible mechanisms involved in this preferential transmission and its impact on translocation colonization.
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Affiliation(s)
- Guillaume Martin
- CIRADUMR AGAPMontpellierF‐34398France
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
| | - Franc‐Christophe Baurens
- CIRADUMR AGAPMontpellierF‐34398France
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
| | - Catherine Hervouet
- CIRADUMR AGAPMontpellierF‐34398France
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
| | - Frédéric Salmon
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
- CIRADUMR AGAPCapesterre‐Belle‐EauGuadeloupeF‐97130France
| | - Jean‐Marie Delos
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
- CIRADUMR AGAPCapesterre‐Belle‐EauGuadeloupeF‐97130France
| | - Karine Labadie
- GenoscopeInstitut de biologie François JacobCommissariat à l'Energie Atomique (CEA)Université Paris‐SaclayEvryFrance
| | - Aude Perdereau
- GenoscopeInstitut de biologie François JacobCommissariat à l'Energie Atomique (CEA)Université Paris‐SaclayEvryFrance
| | - Pierre Mournet
- CIRADUMR AGAPMontpellierF‐34398France
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
| | - Louis Blois
- CIRADUMR AGAPMontpellierF‐34398France
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
| | - Marion Dupouy
- CIRADUMR AGAPMontpellierF‐34398France
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
| | - Françoise Carreel
- CIRADUMR AGAPMontpellierF‐34398France
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
| | - Sébastien Ricci
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
- CIRADUMR AGAPCapesterre‐Belle‐EauGuadeloupeF‐97130France
| | - Arnaud Lemainque
- GenoscopeInstitut de biologie François JacobCommissariat à l'Energie Atomique (CEA)Université Paris‐SaclayEvryFrance
| | - Nabila Yahiaoui
- CIRADUMR AGAPMontpellierF‐34398France
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
| | - Angélique D’Hont
- CIRADUMR AGAPMontpellierF‐34398France
- AGAPUniv MontpellierCIRADINRAEInstitut AgroMontpellier34060France
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The Investigation of Perennial Sunflower Species ( Helianthus L.) Mitochondrial Genomes. Genes (Basel) 2020; 11:genes11090982. [PMID: 32846894 PMCID: PMC7565312 DOI: 10.3390/genes11090982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/23/2022] Open
Abstract
The genus Helianthus is a diverse taxonomic group with approximately 50 species. Most sunflower genomic investigations are devoted to economically valuable species, e.g., H. annuus, while other Helianthus species, especially perennial, are predominantly a blind spot. In the current study, we have assembled the complete mitogenomes of two perennial species: H. grosseserratus (273,543 bp) and H. strumosus (281,055 bp). We analyzed their sequences and gene profiles in comparison to the available complete mitogenomes of H. annuus. Except for sdh4 and trnA-UGC, both perennial sunflower species had the same gene content and almost identical protein-coding sequences when compared with each other and with annual sunflowers (H. annuus). Common mitochondrial open reading frames (ORFs) (orf117, orf139, and orf334) in sunflowers and unique ORFs for H. grosseserratus (orf633) and H. strumosus (orf126, orf184, orf207) were identified. The maintenance of plastid-derived coding sequences in the mitogenomes of both annual and perennial sunflowers and the low frequency of nonsynonymous mutations point at an extremely low variability of mitochondrial DNA (mtDNA) coding sequences in the Helianthus genus.
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20
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Massive haplotypes underlie ecotypic differentiation in sunflowers. Nature 2020; 584:602-607. [PMID: 32641831 DOI: 10.1038/s41586-020-2467-6] [Citation(s) in RCA: 177] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 04/16/2020] [Indexed: 12/22/2022]
Abstract
Species often include multiple ecotypes that are adapted to different environments1. However, it is unclear how ecotypes arise and how their distinctive combinations of adaptive alleles are maintained despite hybridization with non-adapted populations2-4. Here, by resequencing 1,506 wild sunflowers from 3 species (Helianthus annuus, Helianthus petiolaris and Helianthus argophyllus), we identify 37 large (1-100 Mbp in size), non-recombining haplotype blocks that are associated with numerous ecologically relevant traits, as well as soil and climate characteristics. Limited recombination in these haplotype blocks keeps adaptive alleles together, and these regions differentiate sunflower ecotypes. For example, haplotype blocks control a 77-day difference in flowering between ecotypes of the silverleaf sunflower H. argophyllus (probably through deletion of a homologue of FLOWERING LOCUS T (FT)), and are associated with seed size, flowering time and soil fertility in dune-adapted sunflowers. These haplotypes are highly divergent, frequently associated with structural variants and often appear to represent introgressions from other-possibly now-extinct-congeners. These results highlight a pervasive role of structural variation in ecotypic adaptation.
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