College of Life Sciences, Wuhan University, Wuhan, China.
Plant Biol (Stuttg). 2010 Sep 1;12(5):814-9. doi: 10.1111/j.1438-8677.2009.00283.x.
Many plants combine sexual reproduction with some form of asexual reproduction to different degrees, and lower genetic diversity is expected with asexuality. Moreover, the ratios of sexual morphs in species with gender dimorphism are expected to vary in proportion to the reproductive success of the sexual process. Hence, sex ratios can directly influence the genetic structure and diversity of a population. We investigated genotypic diversity in 23 populations of a facultative, apomictic gynodioecious orchid, Satyrium ciliatum, to examine the effect on genotypic diversity of variation in the frequency of females and in the amount of sexual reproduction. The study involved one pure female, seven gynodioecious (both females and hermaphrodites present) and 15 hermaphroditic populations. Pollinia receipt was higher in hermaphroditic than in gynodioecious populations. Analyses of variation in ISSRs demonstrated that genotypic diversity was high in all populations and was not significantly different between hermaphroditic and gynodioecious populations. We used character compatibility analysis to determine the extent to which recombination by sexual reproduction contributed to genotypic diversity. The results indicate that the contribution of recombination to genotypic diversity is higher in hermaphroditic than in gynodioecious populations, consistent with the finding that hermaphroditic populations received higher amounts of pollinia. Our finding of reduced recombination in gynodioecious populations suggests that maintenance of sex in hermaphrodites plays an important role in generating genotypic diversity in this apomictic orchid.
许多植物在不同程度上结合有性生殖和某种形式的无性生殖，而无性生殖预计会降低遗传多样性。此外，具有性别二态性的物种中，有性形态的比例预计会根据有性过程的生殖成功率而变化。因此，性别比例可以直接影响种群的遗传结构和多样性。我们调查了 23 个有性、无融合生殖的雌雄同体兰花 Satyrium ciliatum 的群体的基因型多样性，以研究雌性频率和有性生殖数量变化对基因型多样性的影响。该研究涉及一个纯雌性、七个雌雄同体（既有雌性又有两性）和 15 个两性群体。两性群体的花粉接收量高于雌雄同体群体。ISSRs 分析表明，所有群体的基因型多样性都很高，且两性和雌雄同体群体之间没有显著差异。我们使用特征兼容性分析来确定有性生殖重组对基因型多样性的贡献程度。结果表明，有性生殖对基因型多样性的贡献在两性群体中高于雌雄同体群体，这与两性群体接收更多花粉的发现一致。我们发现雌雄同体群体中重组减少，这表明在这种无融合生殖的兰花中，两性中维持性的作用对于产生基因型多样性非常重要。
