Dissertation Research: The Importance of Mixed Reproductive Strategies on Plant/Pathogen Interactions

在许多物种中，寄生虫可能是维持遗传多样性和繁殖的重要进化因子。植物既可以自交也可以与其他植物杂交。后者比自花受精产生更大的遗传变异。虽然许多植物可以使用这两种机制，但混合系统有利的条件尚未得到很好的理解。蒲公英（Danthonia spicata）是一种可以通过异交和自交花繁殖的草。当被真菌感染时，异交花的发育被阻止，并且在其位置发育出具有感染孢子的真菌结构。这种真菌还可以通过感染自交产生的种子来传播。这种防止异交的寄生虫策略已经在其他系统中观察到，可能有利于寄生虫减少寄主植物的遗传变异，或者因为更多的植物资源可用于真菌繁殖。本项目将研究真菌A. hypoxylon是否维持寄主spicata的混合生殖系统，以及寄主的生殖系统如何影响寄主spicata的成功。每种真菌传播模式（传染性传播或宿主种子感染）的优势令人感兴趣，因为每种模式都与寄生虫对宿主的不同程度的影响有关，并可能导致不同的疾病传播模式。比较寄主在存在病原体的情况下通过自交和异交成功的情况，将阐明维持植物遗传多样性的重要性。这些信息对于制定保护政策以减少濒危物种的疾病损害具有重要意义。它还将对开发更好的农业实践以减轻病原体对作物的损害具有潜在价值。

9520662 CLAY Parasites may be important evolutionary agents for the maintenance of genetic diversity and reproduction in many species. Plants can either self-fertilize or outcross with another plant. The latter produces greater genetic variability than self-fertilization. Although many plants can use both mechanisms, the conditions in which mixed systems are advantageous are not well understood. Danthonia spicata is a grass that can reproduce through outcrossing and selfing flowers. When infected with the fungus Atkinsonella hypoxylon, the development of outcrossing flowers is prevented and a fungal structure that bears infective spores develops in its place. The fungus can also spread by infecting the seeds produced through selfing. This parasite strategy of preventing outcrossing has been observed in other systems and might be advantageous for the parasite to reduce genetic variability of host plants or because more plant resources are available for fungal reproduction. This project will investigate whether the fungus A. hypoxylon acts to maintain the mixed reproductive system in the host D. spicata, and how the host's reproductive system affects the success of the parasite. The advantage of each fungal transmission mode (contagious spread or infection of host seeds) is of interest because each mode is associated with different levels of parasite effect on the host and can lead to different disease spread patterns. Comparison of the host success through selfing and outcrossing in the presence of pathogens will shed light on the importance of maintaining genetic diversity in plants. This information is important for constructing conservation policies for minimizing disease damage in endangered species. It will also be of potential value for developing better agricultural practices to alleviate pathogen damage to crops.