Breeding system studies have indicated the predominance of late-acting self-incompatibility (LSI) in Bignoniaceae, despite the relatively few species investigated, and the occurrence of other kinds of breeding systems in this family. This study aimed to determine the breeding system in T. roseo-alba by means of controlled experimental pollination, histological analysis of post-pollination events, and studies of pistil longevity, in situ pollen tube growth and seed germination. Despite pollen tube penetration and fertilization of most ovules of selfed pistils, 100% of these pistils aborted uniformly between the fourth and sixth day after anthesis onset. Ovary and ovule growth, as well as initial endospermogenesis and proembryonal tube formation were verified in selfed pistils before abscission, but the progress of post-pollination development in these pistils was slower than in crossed pistils. The longevity of self-pollinated pistils was greater than in non-pollinated pistils. Seed germinability was 93%, and all seeds were monoembryonic. These results show that T. roseo-alba is a species with post-zygotic LSI, and with no polyembryony.
endosperm development; late-acting self-incompatibility; proembryonal tube; self-sterility
