Self-sterility and self-fertility of Passiflora L. (Passifloraceae) in the Cerrado of Central Brazil

Abstract

Many species of wild passion fruit are used for the genetic breeding of passion fruit crop and kept in germplasm banks. This study investigated floral biology, breeding system, and chromosome number of Passiflora species that occur in areas of Cerrado in Uberlândia, Minas Gerais, from 2008 to 2010. In general, the species bloomed in the rainy season, the anthesis was diurnal, except for P. tricuspis, and flowers were open from 6 to 12 h. At the time of flower opening, the nectar was already accumulated in the nectariferous chamber. Protandry occurred only in P. tenuifila. Bees were the main flower visitors of these species. There were significant differences in the diameter and length of the floral androgynophore among species. Passiflora amethystina, P. tenuifila (both subgenus Passiflora), and P. suberosa (subgenus Decaloba) were self-fertile, while P. cincinnata (subgenus Passiflora) and P. tricuspis (subgenus Decaloba) were self-sterile, which contrasted with the usual trends in the group. The chromosome number for P. tricuspis was 2n = 12, P. amethystina and P. tenuifila were 2n = 18 chromosomes, and P. suberosa was 2n = 24 chromosomes, which conformed to the recorded results for the group. Overall conservative chromosome numbers, and self-fertility in P. amethystina are interesting results for breeding programs and basic information for conservation.