Dissertation Research: Late-Acting Self-Incompatibility and Post-Pollination Selection in Milkweeds (Asclepias: Asclepiadaceae)

9623925怀亚特大多数开花植物是雌雄同体的，同时产生雄性和雌性生殖器官。因此，自花授粉和异花授粉都是可能的。自花授粉的花通常比异花授粉的花更不容易结实。导致种子产量损失的机制包括遗传自交不亲和系统的作用和早期近交抑制的影响。区分这两种不育原因是具有挑战性的，特别是对于那些表现出晚期自交不亲和或授粉后选择异交后代而不是自交后代的物种。该奖项资助的研究通过实验杂交解决了两种乳草（Asclepias）的这些不同机制。首先，实验将检验自体不育是由于早期近交抑制导致的自交胚胎流产，还是由于晚期自交不亲和导致的自交受精卵排斥。如果涉及迟发性自交不亲和，则确定其遗传基础。其次，解决了授粉后选择在自育马利筋非随机交配中的作用。这些研究将有助于阐明近交抑制和自交不亲和在交配系统进化中的重要性。由于近交抑制在应用农业系统和濒危植物种群中都是一个问题，了解减轻近交的机制可以为作物改良和本地植物保护提供信息。

9623925 Wyatt Most flowering plants are hermaphroditic, producing both male and female reproductive organs. Consequently, self-pollination as well as cross-pollination is possible. Self-pollinated flowers often are less likely to set seed than cross-pollinated flowers. Mechanisms responsible for the loss of seed production include the action of genetic self-incompatibility systems and the effects of early-acting inbreeding depression. Distinguishing between these two causes of sterility is challenging, especially for species that exhibit either late-acting self-incompatibility or post- pollination selection of outcrossed offspring over selfed ones. The research funded by this award resolves these different mechanisms in two species of milkweeds (Asclepias), using experimental crosses. First, experiments will test whether self sterility results from either the abortion of selfed embryos due to early-acting inbreeding depression or the rejection of selfed zygotes based on late-acting self-incompatibility. If late-acting self-incompatibility is implicated, its genetic basis will be determined. Second, the role of post-pollination selection in causing non random mating in a self-fertile milkweed will be resolved. These studies will help to clarify the importance of inbreeding depression and self-incompatibility in mating system evolution. Because inbreeding depression is a problem in both applied agricultural systems and endangered plant populations, understanding mechanisms that alleviate inbreeding can inform efforts for crop improvement and native plant conservation.