Abstract

Microsatellite markers were used to investigate the genetic basis of cowpea yellow mosaic virus (CYMV) resistance in 40 cowpea lines. A total of 60 simple sequence repeat (SSR) primers were used to screen polymorphism between stable resistance (GC-3) and susceptible (Chrodi) genotypes of cowpea. Among these, only 4 primers were polymorphic and these 4 SSR primer pairs were used to detect CYMV resistant genes among 40 cowpea genotypes. The polymorphism information content (PIC) of these SSR markers ranged from 0.30 to 0.72. A dendrogram of these genotypes based on microsatellite polymorphisms generally agreed with the CYMV resistant phenotype of these lines. All the genotypes could be divided into two major groups, separated at 45% similarity. The resistant group comprised of 18 cowpea lines with 77 to 100% similarity, in which 10 genotypes shared 100% similarity. Also, the two resistant lines were classified in a separate group with one susceptible line and joined with resistant group at 47% similarity. The susceptible group consisted of two subgroups with 71 and 77% similarity within each subgroup. 

Key words: Cowpea yellow mosaic virus, resistance, genetic similarity, microsatellite, simple sequence repeat, markers, cowpea, polymorphism.