Induction and exploitation of nuclear and cytoplasmic male sterility in pepper (Capsicum spp.): a review

Abstract

SummaryPepper belongs to the genus Capsicum, of which five species are cultivated (C. annuum L., C. chinense Jacq., C. frutescens L., C. baccatum L. Ruiz. & Pavon, and C. pubescens). C. annuum L., which includes both hot pepper and bell pepper, is the most widely cultivated species. Commercial hybrid pepper seed is produced manually or by exploiting male sterility (MS). Both nuclear (NMS) and cytoplasmic (CMS) MS are available in pepper. Due to recessive gene control, the development of NMS lines through conventional breeding is tedious and time-consuming. Molecular markers linked to the NMS genes ms-1 and ms-8 have been developed. This will facilitate the development of new NMS lines, identify MS plants at the seedling stage, and test the purity of F1 hybrid seed. To reduce hybrid seed costs further, and to improve seed yields, there is a need to identify seedling markers to facilitate the removal of fertile plants in nursery blocks. Most reports have indicated that CMS is sensitive to low temperatures. Restorer-of-fertility genes are common in hot pepper and rare in bell pepper cultivars. Despite conflicting reports, it has been concluded that a single dominant gene (Rf) along with a modifier gene (Pr), controls the restoration of fertility in pepper. Molecular markers linked to the Rf and Pr genes and the mitochondrial CMS genes coxII and atp6 have been developed. These will facilitate the rapid screening of inbred pepper lines for Rf/rf alleles, accelerate the transfer of the rf gene in female hot pepper parents (maintainer breeding), and the Rf gene in male sweet pepper parents (restorer breeding). We have compiled up-to-date information on both NMS and CMS systems in pepper and discuss the prospects for their use in breeding for heterosis.