Genetic variation in Bambara ground nuts as revealed by agro-morphological and DArTseq markers and selection for improved yield performance

Abstract

Bambara groundnut (Vigna subterranea (L.) Verdc) has been neglected in terms of variety selection and development which has resulted in farmers growing a mixture of landraces that are not genetically characterized and are low yielding. With the need to set up a breeding programme in Malawi, it was necessary to thoroughly understand the genetic diversity (GD) present in the available germplasm. The objectives of the study were to assess Bambara genotypes GD using agro-morphological traits and SNP markers, and to identify and select high yielding Bambara genotypes. Field trials were conducted for two seasons at Bunda College. Later, genotypes were genotyped using DartSeqLD SNP markers. All data were analysed using R Package. Significant genetic variations (P < 0.001) were observed for most traits including grain yield, which suggests that genetic variability exists in Bambara groundnuts which can be exploited in breeding programmes aimed at developing high performing varieties. Based on grain yield, the study identified 18 top performing genotypes across the evaluation seasons which will be tested under farmers’ fields’ conditions. DArTseqLD grouped the genotypes into three clusters. It was noted that majority of the genotypes from the same origin clustered together. High genetic distances were observed between genotypes from Southern African and West African regions and this has important implications in parental selection for the genetic improvement of Bambara. Our results provide valuable insights about the extent of genetic variability and how parental lines can be selected for improved genetic gain in Bambara groundnuts.