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）指某基因座的观测基因型频率偏离预期孟德尔分离比例的现象，如今该现象作为一种潜在的强效进化驱动力，已日益受到学界的广泛认可。分离扭曲的核心诱因在于，分离后代中的活力基因座会导致配子与合子的活力出现差异。不过，母本细胞质也可能参与配子和合子的活力选择过程。本研究的目标是对玉米中的分离扭曲基因座（Segregation distortion loci, SDL）进行定位，并验证“配子与合子的活力或与母本细胞质环境相关”这一假说。本研究采用互交育种设计构建了F₂分离群体，利用126个微卫星标记构建了连锁图谱。通过全基因组扫描，对不同母本细胞质环境下的分离群体进行SDL检测。最终，在专门设计的F₂群体中，共鉴定出14个具有较高LOD（logarithm (base 10) of odds）支持度的SDL。有趣的是，我们发现在两种母本细胞质背景下，SDL的基因型频率发生了显著变化，这表明不同细胞质环境下配子与合子的活力发生了改变。此外，在JB细胞质背景中，多数检测到的SDL以及完全扭曲的标记均表现出偏向Y53等位基因的相似偏倚模式。上述结果表明，自私性细胞质元件可能通过调控配子与合子的选择性活力，在塑造F₂群体的分离扭曲模式中发挥重要作用。