PARENT SESSION
Oral Session #31: Plant Reproductive Ecology, Pollination, and Dispersal. Presiding: J. Karron.
Tuesday, August 7, 2001. 1:00 PM to 5:00 PM. Hall of Ideas L&M.

Breakdown in self-incompatibility in a weed (Solanum carolinense).

Travers, Steven¹, Stephenson, Andrew¹, Fedor, Andre¹, ¹

ABSTRACT- Self-incompatibility is thought to be rare in weedy species that must frequently colonize new habitats because self pollination may be the only means of reproducing. Solanum carolinense is an exception because it is a weedy herb with a gametophytic self-incompatibility system controlled by a single S-locus. We designed a breeding experiment to determine: 1) if self-incompatibility is consistent across sequential flowers within an infloresence and sequential infloresences within a plant, 2) if self-incompatibility is influenced by the proportion of previous flowers producing fruits from outcross pollinations, and 3) if clones from different parental lines differ in the degree to which they are self-incompatible? Five clones each of 23 field collected plants were exposed to one of two experimental treatments: self pollination or outcross pollination of the first forty flowers. We measured the fruit and seed set of flowers that were then self pollinated following the initial pollination treatments to measure the degree of self incompatibility. Our results indicate that there is broadsense heritability for a temporal breakdown of self-incompatiblity and that the degree of breakdown is influenced by prior fruit production. These results indicate that there is plasticity in the gametophytic self incompatiblity system in this weedy species where the availability of outcross pollen is often low.

KEY WORDS: mating system, self-incompatibility, plant reproduction, Solanum carolinense