Genetic Diversity among Pigeonpea (Cajanus cajan L. Millsp.) Genotypes Using Genic SSRs with Putative Function for Drought Tolerance

Abstract

One hundred and thirty eight pigeonpea genotypes were analyzed for molecular genetic diversity using 34 SSR markers with putative function for drought tolerance. The study revealed considerable molecular genetic diversity among genotypes. Fifty two alleles were obtained with 34 SSR markers while, 1 to 3 alleles was scored with an average of ~1.6 alleles for each SSR. Three alleles were amplified by markers ASSR1, ASSR93 and ASSR97. Of these, 15 SSR markers were found to be polymorphic which identified 33 alleles among 138 genotypes. The average PIC value of these polymorphic SSRs was 0.22 with a range of 0.01 for ASSR308 to 0.38 in ASSR97. Significant positive correlation was observed between PIC values with number of alleles amplified per primer (r = 0.58*, P < 0.05), and gene diversity (r = 0.99**, P < 0.01) and between allele number and gene diversity (r = 0.57*, P<0.05). The average genetic distance for all pair wise comparisons was estimated as 0.27. The highest genetic distance of 0.69 was recorded between genotypes PAU-881 and LRG-41. Cluster analysis, done by UPGMA following Nei's similarity matrix and population structure analyses grouped 138 pigeonpea genotypes into seven sub-populations.