Segregation distortion in Arabidopsis C24/Col-0 and Col-0/C24 recombinant inbred line populations is due to reduced fertility caused by epistatic interaction of two loci.
ABSTRACT A new large set of reciprocal recombinant inbred lines (RILs) was created between the Arabidopsis accessions Col-0 and C24 for quantitative trait mapping approaches, consisting of 209 Col-0 x C24 and 214 C24 x Col-0 F(7 )RI lines. Genotyping was performed using 110 evenly distributed framework single nucleotide polymorphism markers, yielding a genetic map of 425.70 cM, with an average interval of 3.87 cM. Segregation distortion (SD) was observed in several genomic regions during the construction of the genetic map. Linkage disequilibrium analysis revealed an association between a distorted region at the bottom of chromosome V and a non-distorted region on chromosome IV. A detailed analysis of the RILs for these two regions showed that an SD occurred when homozygous Col-0 alleles on chromosome IV coincided with homozygous C24 alleles at the bottom of chromosome V. Using nearly isogenic lines segregating for the distorted region we confirmed that this genotypic composition leads to reduced fertility and fitness.
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ABSTRACT: Crossing experiments indicate that hybrid sterility barriers frequently have developed within diploid, circumpolar plant species of the genus Draba. To gain insight into the rapid evolution of postzygotic reproductive isolation in this system, we augmented the linkage map of one of these species, D. nivalis, and searched for quantitative trait loci (QTLs) associated with reproductive isolation. The map adds 63 new dominant markers to a previously published dataset of 31 co-dominant microsatellites. These markers include 52 amplified fragment length polymorphisms (AFLPs) and 11 sequence-specific amplified polymorphisms (SSAPs) based on retrotransposon sequence. 22 markers displaying transmission ratio distortion were further included in the map. We resolved eight linkage groups with a total map length of 894 cM. Significant genotype-trait associations, or quantitative trait loci (QTL), were detected for reproductive phenotypes including pollen fertility (4 QTLs), seed set (3 QTLs), flowering time (3 QTLs) and number of flowers (4 QTLs). Observed patterns of inheritance were consistent with the influence of both nuclear-nuclear interactions and chromosomal changes on these traits. All seed set QTLs and one pollen fertility QTL displayed underdominant effects suggestive of the involvement of chromosomal rearrangements in hybrid sterility. Interestingly, D. nivalis is predominantly self-fertilizing, which may facilitate the establishment of underdominant loci and contribute to reproductive isolation.PLoS ONE 01/2014; 9(4):e93834. · 3.53 Impact Factor
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ABSTRACT: Cryptic genetic variation (CGV) is invisible under normal conditions, but it can fuel evolution when circumstances change. In theory, CGV can represent a massive cache of adaptive potential or a pool of deleterious alleles that are in need of constant suppression. CGV emerges from both neutral and selective processes, and it may inform about how human populations respond to change. CGV facilitates adaptation in experimental settings, but does it have an important role in the real world? Here, we review the empirical support for widespread CGV in natural populations, including its potential role in emerging human diseases and the growing evidence of its contribution to evolution.Nature Reviews Genetics 03/2014; · 41.06 Impact Factor
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ABSTRACT: Female control of nonrandom mating has never been genetically established, despite being linked to inbreeding depression and sexual selection. In order to map the loci that control female-mediated nonrandom mating, we constructed a new advanced intercross recombinant inbred line (RIL) population derived from a cross between Arabidopsis thaliana accessions Vancouver (Van-0) and Columbia (Col-0) and mapped quantitative trait loci (QTL) responsible for nonrandom mating and seed yield traits. We genotyped a population of 490 recombinant inbred lines. A subset of these lines was used to construct an expanded map of 1061.4 cM with an average interval of 6.7±5.3 cM between markers. QTL were then mapped for female- and male-mediated nonrandom mating and seed yield traits. To map the genetic loci responsible for female-mediated nonrandom mating and seed yield, we performed mixed pollinations with Col-NPTII and Van-0 pollen on RIL pistils. To map the loci responsible for male-mediated nonrandom mating and seed yield, we performed mixed pollinations with Col-NPTII and RIL pollen on Van-0 pistils. Composite interval mapping of these data identified four QTLs that control female-mediated nonrandom mating, and five QTLs that control female-mediated seed yield. We also identified four QTLs that control male-mediated nonrandom mating, and three QTLs that control male-mediated seed yield. Epistasis analysis indicates that several of these loci interact. To our knowledge, the results of these experiments represent the first time female-mediated nonrandom mating has been genetically defined.Plant physiology 03/2014; · 6.56 Impact Factor