Cross-transferable microsatellite markers from Vigna Savi. are useful for assessing genetic diversity in wild and cultivated Cajanus Adans. species.

We assessed 61 'Vigna' (azuki bean)-specific microsatellite markers for their cross transferability and efficiency in supporting diversity studies in 'Cajanus'. Thirty 'Cajanus' genotypes comprising 20 different cultivars of pigeonpea ('C. cajan') and ten genotypes from five wild relatives of pigeonpea were examined in this study. Of the 61 SSR primer pairs screened, 18 amplified distinct and scorable amplicons 90-600 bp in size, revealing 32 alleles. The percentage transferability of these 18 markers ranged from 31.60% to 100%. Eight primer pairs (CEDG 56, CEDG 91, CEDG 139, CEDG 268, CEDG 275, CEDG 06, CEDG 88 and CEDG 257) amplified SSRs from the 30 genotypes examined, indicating 100% transferability. Except for CEDG 06, all markers with 100% transferability amplified di-nucleotide repeat motifs, with (AG)n as the only repeats. The Polymorphic Information Content (PIC) ranged from 0.24 in CEDG 176 to 0.69 in CEDG 127, with an average of 0.47. The UPGMA clustering method, which we used to assess the genetic distances and relatedness of the genotypes using the 18 successful markers, produced a dendrogram with two clusters, separating all 20 cultivars from the wild relatives at 67% similarity. 'C. cajanifolius' (ICP 1629-1 and ICP 1629-2), which was previously reported to be a progenitor of 'C. cajan', clustered with the cultivars. The results of this study affirm the transferability of SSR markers within related legume genera. The identified 'Vigna' SSRs will be useful for increasing the marker repository of pigeonpea and for diversity studies of pigeonpea cultivars.