Analysis of Genetic Diversity and Population Structure of Pigeonpea [Cajanus cajan (L.) Millsp] Accessions Using SSR Markers

Understanding the genetic diversity present amongst crop genotypes is an efficient utilization of germplasm for genetic improvement. The present study was aimed at evaluating genetic diversity and population structure of 48 pigeonpea genotypes from four populations collected from diverse sources. The 48 pigeonpea entries were genotyped using 33 simple sequence repeat (SSR) markers that are polymorphic to assess molecular genetic diversity and genetic relatedness. The informative marker combinations revealed a total of 155 alleles at 33 loci, with an average of 4.78 alleles detected per marker with the mean polymorphic information content (PIC) value of 0.46. Population structure analysis using model based revealed that the germplasm was grouped into two subpopulations. The analysis of molecular variance (AMOVA) revealed that 53.3% of genetic variation existed within individuals. Relatively low population differentiation was recorded amongst the test populations indicated by the mean fixation index (Fst) value of 0.032. The Tanzanian pigeonpea germplasm collection was grouped into three major clusters. The clustering pattern revealed a lack of relationship between geographic origin and genetic diversity. This study provides a foundation for the selection of parental material for genetic improvement.