Causes and Consequences of an Age Dependent Breakdown in Self-Incompatibility in Campanula rapunculoides

9982086斯蒂芬森许多植物物种具有遗传自交不亲和（SI）系统，因此自交花粉的受精被阻止。这可以使植物避免近亲繁殖的有害影响，但当无法获得杂交花粉时，可能会减少种子产量。先前的研究表明，风铃花（Campanula rapunculloides）在首次开放时是SI的，但随着花的年龄增长，其自相容性会增强。简而言之，当有异交花粉时，风铃花的近亲繁殖水平较低，而当没有异交花粉时，其种子产量较高。本研究探讨分子，遗传和生态的原因，这种年龄依赖性的崩溃在SI。第一个项目将分离、克隆和测序指定SI （S-locus）的DNA。第二项将量化近亲繁殖抑制的数量，这是由于与s位点密切相关的基因。第三篇研究了强SI和弱SI植物在两种环境下的适合度。这些项目将提供以下方面的见解：(a)花识别和拒绝自交花粉的机制，(b) s位点的起源、维持和进化，以及(c)适合度与育种系统之间的关系。这些基本发现也应该有助于植物育种家、保护生态学家和那些对转基因生物基因逃逸感兴趣的人。

9982086StephensonMany plant species possess genetic self-incompatibility (SI) systems whereby fertilization by self-pollen is prevented. This allows plants to avoid the deleterious effects of inbreeding but may reduce seed production when cross pollen is unavailable. Previous studies have shown that bellflowers (Campanula rapunculoides) are SI when they first open but become more self-compatible as the flowers' age. In short, bellflowers have low levels of inbreeding when cross-pollen is available and high seed production when it is not. This research examines the molecular, genetic, and ecological causes of this age dependent breakdown in SI. The first project will isolate, clone, and sequence the DNA that specifies SI (S-locus). The second will quantify the amount of inbreeding depression that is due to genes that are closely linked to the S-locus. The third examines the fitness of plants with strong and weak SI in two environments.These projects will provide insights into (a) the mechanism by which self-pollen is recognized and rejected by flowers, (b the origin, maintenance and evolution of the S-locus, and (c) the relationship between fitness and the breeding system. These basic findings should also assist plant breeders, conservation ecologists, and those interested in the escape of genes from genetically modified organisms.