Cytoplasmic male sterility and inter and intra subgenomic heterosis studies in Brassica species: A review

Plants of the genus Brassica comprise a remarkably diverse group of crops and encompass varieties that are grown as oilseeds, vegetables, condiment mustards and forages. One of the basic requirements for developing hybrid varieties in oilseed Brassica is the availability of proven heterosis. The development of hybrid cultivars has been successful in many Brassica spp. Midparent heterosis and high-parent heterosis (heterobeltiosis) have extensively been explored and utilized for boosting various quantity and quality traits in rapeseed. Heterosis is commercially exploited in rapeseed and its potential use has been demonstrated in turnip rape (B. rapa L.) and Indian mustard (B. juncea L.) for seed yield and most of the agronomic traits. The oilseed rape plant, B. napus, possesses two endogenous male sterile cytoplasms, nap and pol. Ogura type of cytoplasmic male sterility was first discovered in Japanese wild radish and other male-sterile Brassicas (Ogura bearing cytoplasm) derived from interspecific crosses. Information concerning the allelic frequencies of restorers can be useful in trying to understand their evolutionary origins. The ogu, pol and nap cytoplasms of B. napus induce sterility in all, some, and only a few cultivars, respectively. In this study, different kinds of male sterility, combining ability and heterosis of qualitative and quantitative traits in different Brassica species will be revi?wed.