Genetic resources and breeding of Capsicum spp.

Abstract

Five species of Capsicum have been domesticated in the American tropics, but breeding programs have concentrated on the non-pungent cultivars of C. annuum. Studies of the consequences of human selection during and after domestication support theoretical calculations that there will be significant amounts of genetic diversity within as well as between species. Breeders have only recently begun to exploit this diversity. Multiple resistances are available to several pests and diseases, but have to be transferred from one agronomic or market type of pepper to another. Problems in selecting simultaneously for multigenic resistances and polygenic quality characters may be eased by the development of molecular markers and a molecular linkage map for Capsicum. Ploidy changes (both tetraploidy and haploidy) are relatively easy to induce in Capsicum species. Doubled haploids have proved particularly valuable in the analysis of the genetically complex basis of some resistances to pests and diseases. Barriers to interspecific gene transfer are similar to those found in other genera of Solanaceae: unilateral incompatibility, post-fertilisation abortion, and nucleo-cytoplasmic interactions leading to male sterility or other abnormalities. Information on the occurrence and effects of these barriers should be available if or when breeders need to turn to interspecific hybridisation.