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

9982086

Stephenson

Many 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.