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

9982086斯蒂芬森许多植物具有遗传自交不亲和(SI)系统，从而阻止自花授粉受精。这使得植物可以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。以前的研究表明，风铃花在第一次开放时是SI的，但随着花的年龄变得更具自亲和性。简而言之，当有异花授粉时，风铃花的近亲繁殖水平较低，而当没有异花授粉时，风铃花的种子产量较高。这项研究从分子、遗传和生态学的角度探讨了这种年龄相关的SI崩溃的原因。第一个项目将分离、克隆和测序指定SI(S基因座)的dna。第二个将量化近亲繁殖抑郁的数量，这些近亲繁殖抑郁是由与S基因紧密连锁的基因造成的。第三项研究考察了具有强和弱SI的植物在两种环境中的适合度。这些项目将为深入了解(A)花识别和拒绝自交花粉的机制，(B)S基因座的起源、维持和进化，以及(C)适合度与育种系统的关系。这些基本发现也应该有助于植物育种者、保护生态学家和那些对从转基因生物中逃脱基因感兴趣的人。

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.