Identification of SSR marker associated with rust resistance in cowpea (Vigna unguiculata L.) using bulk segregant analysis

Abstract

Bulked segregant analysis was undertaken to tag gene(s) controlling rust resistance using molecular markers in cowpea, to permit rapid selection of superior desirable rust resistant genotypes in the breeding program. For this purpose, the C-152, cultivated variety with high yielding, semi determinate plant type, good protein content and highly rust susceptible was crossed with genotype IC202778, the landrace from Himachal Pradesh, India having determinate, semi spreading and rust resistant characters. The parental genotypes were analyzed with 92 SSR markers for detection of polymorphism and only 13 markers showed polymorphism between the parents. Using each of these 13 SSR primers, we carried out bulked segregate analysis on F2 plants representing two extremes of rust disease resistance and susceptible trait. Three SSR markers VuUGM02, VuUGM08 and VuUGM19 were found to be associated with rust resistance. This was further confirmed through selective genotyping. The co-segregation data on these molecular markers and rust resistance on F2 plants were analysed by means of single-marker linear regression approach. Significant regression suggested linkage between VuUGM02 and rust resistance gene.