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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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Xiong W, Berke L, Michelmore R, van Workum DJM, Becker FFM, Schijlen E, Bakker LV, Peters S, van Treuren R, Jeuken M, Bouwmeester K, Schranz ME. The genome of Lactuca saligna, a wild relative of lettuce, provides insight into non-host resistance to the downy mildew Bremia lactucae. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 115:108-126. [PMID: 36987839 DOI: 10.1111/tpj.16212] [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: 10/29/2022] [Revised: 02/20/2023] [Accepted: 02/27/2023] [Indexed: 06/19/2023]
Abstract
Lactuca saligna L. is a wild relative of cultivated lettuce (Lactuca sativa L.), with which it is partially interfertile. Hybrid progeny suffer from hybrid incompatibility (HI), resulting in reduced fertility and distorted transmission ratios. Lactuca saligna displays broad-spectrum resistance against lettuce downy mildew caused by Bremia lactucae Regel and is considered a non-host species. This phenomenon of resistance in L. saligna is called non-host resistance (NHR). One possible mechanism behind this NHR is through the plant-pathogen interaction triggered by pathogen recognition receptors, including nucleotide-binding leucine-rich repeat (NLR) proteins and receptor-like kinases (RLKs). We report a chromosome-level genome assembly of L. saligna (accession CGN05327), leading to the identification of two large paracentric inversions (>50 Mb) between L. saligna and L. sativa. Genome-wide searches delineated the major resistance clusters as regions enriched in NLRs and RLKs. Three of the enriched regions co-locate with previously identified NHR intervals. RNA-seq analysis of Bremia-infected lettuce identified several differentially expressed RLKs in NHR regions. Three tandem wall-associated kinase-encoding genes (WAKs) in the NHR8 interval display particularly high expression changes at an early stage of infection. We propose RLKs as strong candidates for determinants of the NHR phenotype of L. saligna.
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Affiliation(s)
- Wei Xiong
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Lidija Berke
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Richard Michelmore
- Genome Center and Department of Plant Sciences, University of California, Davis, CA, USA
| | | | - Frank F M Becker
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Elio Schijlen
- Bioscience, Wageningen University and Research, Wageningen, The Netherlands
| | - Linda V Bakker
- Bioscience, Wageningen University and Research, Wageningen, The Netherlands
| | - Sander Peters
- Bioscience, Wageningen University and Research, Wageningen, The Netherlands
| | - Rob van Treuren
- Centre for Genetic Resources, The Netherlands (CGN), Wageningen University and Research, Wageningen, The Netherlands
| | - Marieke Jeuken
- Plant Breeding, Wageningen University and Research, Wageningen, The Netherlands
| | - Klaas Bouwmeester
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
| | - M Eric Schranz
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
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Id-Lahoucine S, Casellas J, Miglior F, Schenkel FS, Cánovas A. Parent-offspring genotyped trios unravelling genomic regions with gametic and genotypic epistatic transmission bias on the cattle genome. Front Genet 2023; 14:1132796. [PMID: 37091801 PMCID: PMC10117652 DOI: 10.3389/fgene.2023.1132796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 03/20/2023] [Indexed: 04/08/2023] Open
Abstract
Several biological mechanisms affecting the sperm and ova fertility and viability at developmental stages of the reproductive cycle resulted in observable transmission ratio distortion (i.e., deviation from Mendelian expectations). Gene-by-gene interactions (or epistasis) could also potentially cause specific transmission ratio distortion patterns at different loci as unfavorable allelic combinations are under-represented, exhibiting deviation from Mendelian proportions. Here, we aimed to detect pairs of loci with epistatic transmission ratio distortion using 283,817 parent-offspring genotyped trios (sire-dam-offspring) of Holstein cattle. Allelic and genotypic parameterization for epistatic transmission ratio distortion were developed and implemented to scan the whole genome. Different epistatic transmission ratio distortion patterns were observed. Using genotypic models, 7, 19 and 6 pairs of genomic regions were found with decisive evidence with additive-by-additive, additive-by-dominance/dominance-by-additive and dominance-by-dominance effects, respectively. Using the allelic transmission ratio distortion model, more insight was gained in understanding the penetrance of single-locus distortions, revealing 17 pairs of SNPs. Scanning for the depletion of individuals carrying pairs of homozygous genotypes for unlinked loci, revealed 56 pairs of SNPs with recessive epistatic transmission ratio distortion patterns. The maximum number of expected homozygous offspring, with none of them observed, was 23. Finally, in this study, we identified candidate genomic regions harboring epistatic interactions with potential biological implications in economically important traits, such as reproduction.
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Affiliation(s)
- Samir Id-Lahoucine
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | - Joaquim Casellas
- Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Filippo Miglior
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | - Flavio S. Schenkel
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | - Angela Cánovas
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
- *Correspondence: Angela Cánovas,
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Zhang C, Wang J, Xiao X, Wang D, Yuan Z, Zhang X, Sun W, Yu S. Fine Mapping of Two Interacting Loci for Transmission Ratio Distortion in Rice ( Oryza sativa L.). FRONTIERS IN PLANT SCIENCE 2022; 13:866276. [PMID: 35422832 PMCID: PMC9002327 DOI: 10.3389/fpls.2022.866276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/01/2022] [Indexed: 06/14/2023]
Abstract
Transmission ratio distortion (TRD) denotes the observed allelic or genotypic frequency deviation from the expected Mendelian segregation ratios in the offspring of a heterozygote. TRD can severely hamper gene flow between and within rice species. Here, we report the fine mapping and characterization of two loci (TRD4.1 and TRD4.2) for TRD using large F2 segregating populations, which are derived from rice chromosome segment substitution lines, each containing a particular genomic segment introduced from the japonica cultivar Nipponbare (NIP) into the indica cultivar Zhenshan (ZS97). The two loci exhibited a preferential transmission of ZS97 alleles in the derived progeny. Reciprocal crossing experiments using near-isogenic lines harboring three different alleles at TRD4.1 suggest that the gene causes male gametic selection. Moreover, the transmission bias of TRD4.2 was diminished in heterozygotes when they carried homozygous TRD4.1 ZS97. This indicates an epistatic interaction between these two loci. TRD4.2 was mapped into a 35-kb region encompassing one candidate gene that is specifically expressed in the reproductive organs in rice. These findings broaden the understanding of the genetic mechanisms of TRD and offer an approach to overcome the barrier of gene flow between the subspecies in rice, thus facilitating rice improvement by introgression breeding.
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Affiliation(s)
- Chaopu Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jilin Wang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Xiongfeng Xiao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Dianwen Wang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Zhiyang Yuan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Xiaodan Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Wenqiang Sun
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Sibin Yu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, China
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Xia F, Ouyang Y. Recurrent breakdown and rebalance of segregation distortion in the genomes: battle for the transmission advantage. ABIOTECH 2020; 1:246-254. [PMID: 36304131 PMCID: PMC9590546 DOI: 10.1007/s42994-020-00023-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 05/28/2020] [Indexed: 01/25/2023]
Abstract
Mendel's laws state that each of the two alleles would segregate during gamete formation and show the same transmission ratio in the next generation. However, an unexpected biased allele transmission was first detected in Drosophila a century ago, and was subsequently observed in other animals, plants, and microorganisms. Such segregation distortion (SD) shows substantial effects in population structure and fitness of the progenies, which would ultimately lead to reproductive isolation and speciation. Here, we trace the early investigations on the violation of Mendelian genetic principle, which appears as a wide-existence phenomenon rather than a case of exception. The occurence of SD in the whole genome was observed in a number of plant species at the single- and multi-locus level. Biased transmission ratio might occur at meiosis stage due to asymmetric movement of the chromosome; transmission ratio advantage is also caused by interaction and battle between the alleles from respective genomes at the genetic and molecular level. The origin of a SD system is likely to be determined by coevolution of the killer and protector via recurrent breakdown or rebalance loop. These updated understandings also promote genetic improvement of hybrid crops.
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Affiliation(s)
- Fan Xia
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, 430070 China
| | - Yidan Ouyang
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, 430070 China
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Zhang C, Wang D, Wang J, Sun Q, Tian L, Tang X, Yuan Z, He H, Yu S. Genetic Dissection and Validation of Chromosomal Regions for Transmission Ratio Distortion in Intersubspecific Crosses of Rice. FRONTIERS IN PLANT SCIENCE 2020; 11:563548. [PMID: 33193492 PMCID: PMC7655136 DOI: 10.3389/fpls.2020.563548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 09/17/2020] [Indexed: 05/17/2023]
Abstract
Transmission ratio distortion (TRD) refers to a widespread phenomenon in which one allele is transmitted by heterozygotes more frequently to the progeny than the opposite allele. TRD is considered as a mark suggesting the presence of a reproductive barrier. However, the genetic and molecular mechanisms underlying TRD in rice remain largely unknown. In the present study, a population of backcross inbred lines (BILs) derived from the cross of a japonica cultivar Nipponbare (NIP) and an indica variety 9311 was utilized to study the genetic base of TRD. A total of 18 genomic regions were identified for TRD in the BILs. Among them, 12 and 6 regions showed indica (9311) and japonica (NIP) alleles with preferential transmission, respectively. A series of F2 populations were used to confirm the TRD effects, including six genomic regions that were confirmed by chromosome segment substitution line (CSSL)-derived F2 populations from intersubspecific allelic combinations. However, none of the regions was confirmed by the CSSL-derived populations from intrasubspecific allelic combination. Furthermore, significant epistatic interaction was found between TRD1.3 and TRD8.1 suggesting that TRD could positively contribute to breaking intersubspecific reproductive barriers. Our results have laid the foundation for identifying the TRD genes and provide an effective strategy to breakdown TRD for breeding wide-compatible lines, which will be further utilized in the intersubspecific hybrid breeding programs.
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Affiliation(s)
- Chaopu Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Dianwen Wang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jilin Wang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Qiang Sun
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Li Tian
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Xinxin Tang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Zhiyang Yuan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Hanzi He
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- *Correspondence: Hanzi He,
| | - Sibin Yu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- Sibin Yu,
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Fishman L, McIntosh M. Standard Deviations: The Biological Bases of Transmission Ratio Distortion. Annu Rev Genet 2019; 53:347-372. [DOI: 10.1146/annurev-genet-112618-043905] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The rule of Mendelian inheritance is remarkably robust, but deviations from the equal transmission of alternative alleles at a locus [a.k.a. transmission ratio distortion (TRD)] are also commonly observed in genetic mapping populations. Such TRD reveals locus-specific selection acting at some point between the diploid heterozygous parents and progeny genotyping and therefore can provide novel insight into otherwise-hidden genetic and evolutionary processes. Most of the classic selfish genetic elements were discovered through their biasing of transmission, but many unselfish evolutionary and developmental processes can also generate TRD. In this review, we describe methodologies for detecting TRD in mapping populations, detail the arenas and genetic interactions that shape TRD during plant and animal reproduction, and summarize patterns of TRD from across the genetic mapping literature. Finally, we point to new experimental approaches that can accelerate both detection of TRD and characterization of the underlying genetic mechanisms.
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Affiliation(s)
- Lila Fishman
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812, USA
| | - Mariah McIntosh
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812, USA
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