Data from: The maternal cytoplasmic environment may be involved in the viability selection of gametes and zygotes

Segregation distortion is the phenomenon whereby the observed genotypic frequencies of a locus fall outside the expected Mendelian segregation ratio, and it is increasingly recognised as a potentially powerful evolutionary force. The main reason for segregation distortion is a difference in the viability of gametes and zygotes caused by viability loci in the segregating progeny. However, the maternal cytoplasm may also be involved in the viability selection of gametes and zygotes. The objectives of this study were to map the segregation distortion loci (SDL) in maize and to test the hypothesis that the viability of gametes and zygotes may also be associated with the maternal cytoplasmic environment. In the present study, a reciprocal mating design was conducted to generate an F2-segregating population. A linkage map was constructed with 126 microsatellite markers. A whole-genome scan was performed to detect the SDL in segregating populations with different maternal cytoplasm environments. Altogether, 14 SDL with strong LOD (logarithm (base 10) of odds) supports were identified in the specifically designed F2 populations. Interestingly, we found dramatic changes in the genotypic frequencies of the SDL in the two maternal cytoplasmic backgrounds, which indicated a change in the viability of gametes and zygotes in different cytoplasmic environments. Furthermore, in the JB cytoplasmic background, most of the detected SDL and complete distortion markers exhibited similar bias patterns favouring the Y53 alleles. These results suggested that selfish cytoplasmic elements may have an important role in shaping the patterns of segregation distortion in F2 populations through selective viability of gametes and zygotes.分离扭曲（segregation distortion）是指某一位点（locus）的实测基因型频率偏离预期孟德尔分离比例的现象，如今该现象已被学界广泛认可为一类极具潜力的进化动力。分离扭曲的核心成因是分离后代中生活力位点（viability loci）介导的配子与合子生活力差异。此外，母本细胞质（maternal cytoplasm）也可能参与配子与合子的生活力选择过程。本研究的目标为定位玉米中的分离扭曲位点（segregation distortion loci, SDL），并验证“配子与合子的生活力或与母本细胞质环境相关”这一假说。 本研究通过互交交配设计（reciprocal mating design）构建了F2分离群体（F2-segregating population），利用126个微卫星标记（microsatellite markers）构建连锁图谱，并针对携带不同母本细胞质环境的分离群体开展全基因组扫描（whole-genome scan）以检测分离扭曲位点。最终在专门设计的F2群体中，共鉴定出14个具有显著LOD（对数优势比，logarithm (base 10) of odds）值支持的分离扭曲位点。 值得注意的是，我们发现两种母本细胞质背景下，分离扭曲位点的基因型频率存在显著变化，这提示不同细胞质环境下配子与合子的生活力发生了改变。进一步分析显示，在JB细胞质背景中，多数检测到的分离扭曲位点以及完全扭曲的标记均表现出偏向Y53等位基因（allele）的相似偏态模式。上述结果表明，自私细胞质元件（selfish cytoplasmic elements）或可通过调控配子与合子的选择性生活力，在塑造F2群体的分离扭曲模式中发挥关键作用。