Preliminary genetic diversity Analysis of introduced and local Zimbabwe cowpea landraces

Abstract

Cowpea, Vigna Unguiculata plays an important role in human diets because of its good protein quality and high nutritional value. On hand are two cowpea lines sourced from a local Zimbabwean humanitarian organization, with an aim to diversify the local germplasm base of cowpea. Activities involved characterizing and evaluating the foreign sourced lines alongside local ones for morphological and random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) diversity. Five seed characteristics were evaluated, namely seed size, color, uniformity, presence or absence of seed spots and hilum color using specified scales. For RAPD-PCR analysis, a set of five oligonucleotides was used. DNA extraction, quantification, amplification, electrophoresis and band analysis of presence or absence of bands was carried out. Data was collected and an ANOVA was carried out using genstat discovery software. After an ANOVA, principal components analysis (PCA) and hierarchical cluster analysis were used to examine distribution patterns in the germplasm. Significant differences were observed for the five variables (pE‚0.001). Both morphological and molecular data for the cowpea lines show limited diversity from results of multivariate analysis. The dendrogram for morphological data shows an overall similarity index of 78%, whereas for molecular data shows a similarity index of 75%. Of the two foreign lines, the white seeded foreign line, NGO1, seems to be consistently diverse from the rest. It will be a valuable addition to the collection and will be useful for possible introgression in future. The genetic diversity for the collection is generally low and may require continued enrichment with introductions in future. Key words: Random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) characterization, variables, primers, electrophoresis, gel scoring.