Genetic variability in the Solanum nigrum L. complex and related species in South Africa

Solanum nigrum L. and its related species can play a significant role in the food supply and nutrition of people in subsistence farming societies in Africa. - The objectives of this study were to conduct morphological trials on the parent material and progeny and to determine heterosis and correlation of the progeny to identify desirable characters that can be used in further breeding studies. The identification of the species was confirmed with the help of cytogenetics and. the crossability of five species was investigated. The genetic relationships between the different species and progeny were established. The total protein percentaqe, sugar content and pH of the different parental species was also determinate. - Seeds were obtained from several sources and seedlings were grown in a heatcontrolled glasshouse. Established plants were planted out in a glasshouse and two field locations, these plants were used in the various investigations. The experimental designs were complete randomized blocks with three or four replications. - The 15 morphological characters studied were subjected to an ANOVA. and significant differences were found between the accessions tested. - Cytological analyses were carried out and regard to the chromosome numbers the species seem to fit into the normal euploid series. - The ANOVA on the parents and progeny showed significant difference reflecting the extensive genetic differences between them. Solanum scabrum was an excellent parent and selections for characteristics like fruit per bunch and fruit size should lead to improved plants. - AFLP markers were used to distinguish polymorph isms between 14 species in this study. Three primer combinations between ECOR I and MSE, were used and multiple polymorph isms (62%) were detected. - Seven independent sequences and their reverse sequences were selected for use as primers in the SSR study. The genetic distance value amongst the species-and their progeny indicates the diversity but close relationship among the species tested. - The young leaves and fruit of the parental species used in the crossing study were used in the assessments of the protein percentage, sugar and acid content of the plants. - The protein percentages were in most cases higher in the fruit than the leaves except for Solanum scebrum; one of the species often used as leafy vegetable in Africa. - The TSS value in the fruit juice was inversely proportional to the size of the fruit. - The Solanum nigrum complex and related species is a rich, untapped source of characteristics and could be used to improve the crop and probably other species in the Solanaceae family.