Induced mutagenesis as a breeding strategy for improvement of Solanaceous vegetables

The Solanaceae are a cosmopolitan family containing many essential vegetables and fruits such as potato (Solanum tuberosum L.), tomato (Lycopersicon esculentum L.), eggplant (Solanum melongena L.), paprika, chillies, green and red peppers (Capsicum annuum L.), jasmine nightshade (Solanum jasminoides Paxt.), winter cherry (Solanum pseudocapsicum L.), and Cape gooseberry, ornamentals such as Petunia, Schizanthus, and Lycium species, and medicinal plants such as bittersweet (Solanum dulcamara L.) and Solanum viarum Dun., both used as sources of corticosteroids. It also contains tobacco (Nicotiana spp.) - one of the most harmful yet economically important plants in the world - together with many other plants of both poisonous and medicinal value such as belladonna (Atropa belladona L.), stramonium (Datura stramonium L.), black henbane (Hyoscyamus niger L.), and African nightshade (Solanum villosum). Composed of approximately 90 genera and between 2000 and 3000 species, the family is widely distributed throughout the tropical and temperate regions of the world, with centers of diversity occurring in Central and South America, Australia, and Africa (EDMONDS 1978; SYMON 1981; D'ARCY 1991). Work to develop new varieties of improved solanaceous crops started more than 2 centuries ago. This paper reviews some of the recent developments in various aspects of varietal improvement of solanaceous vegetables through mutation breeding. Mutational work reported here includes the alteration of plant reproductive or vegetative growth and the development of locally adapted cultivars and popular breeding lines, or the induction of novel alleles. The potential for direct application of the mutants as new improved cultivars, their use in cross-breeding schemes, and their application in, for example, marker technology in genetic research are discussed. Specific examples of novel mutants developed in our laboratory that have the potential for application in improving solanaceous fruits (represented by tomato) and leafy vegetables (represented by African nightshade) are reported. (author)