Characterization and identification of SSR markers for screening of cowpea genotypes against Bean common mosaic virus (BCMV) disease resistance

One hundred cowpea genotypes were screened against Bean common mosaic virus (BCMV) by artificial inoculation genotypes. The genotypes showed different disease reaction viz., immune, resistant, moderately resistant, Sap moderately susceptible, susceptible and highly susceptible. The SSR markers were characterized using a total of 25 randomly selected resistance and susceptible cowpea genotypes. Among, 10 SSR markers used to screen polymorphism, only 4 primers were found to be polymorphic and they were used for characterization and finding out genetic relationship of cowpea genotypes. The polymorphism information content (PIC) of these SSR markers ranged from 0.23 to 0.37 and single marker analysis (SMA) revealed, out of these 4 SSR markers M 135 marker explained 28.2% of phenotypic variation (R²). The banding pattern of all cowpea genotypes were scored and dendrogram was constructed. A dendrogram of these genotypes based on S SR polymorphism divided into two maj or clusters at 35% similarity. Cluster I was the biggest with 20 genotypes which was further separated as three sub-clusters. Whereas, 5 genotypes grouped in cluster II with two small sub-clusters. The clustering pattern of resistant and susceptible genotypes was not clear, however resistant genotypes such as V-5 and IC 8996 clustered in one group with 100% similarity. The information provided by the identified markers would be very useful in breeding programs to select cowpea lines resistance to BCMV disease and M 135 was found to be good for rapid and accurate screening of cowpea genotypes against BCMV disease resistance.