SSR-marker Assisted Evaluation of Genetic Diversity in Greengram [Vigna radiata (L.) Wilcezk]

Abstract

Background: Assessing genetic diversity in greengram is a prerequisite for its genetic improvement for yield and quality. DNA markers such as simple sequence repeats (SSRs) have been preferred in this crop for the analysis of genetic diversity because SSR markers are locus-specific, widely dispersed throughout the genome, highly polymorphic due to variation in repeat units, highly informative because of co-dominant nature, high reproducibility and ease of assay by PCR (Polymerase chain reaction). The current study aimed to study the genetic diversity among the mutants of greengram at the molecular level using SSR markers. Methods: In this study, twenty-five SSR markers were used to analyze the genetic diversity amongst twenty mutant genotypes of greengram along with their parents. Genomic DNA was isolated from the leaves by using the standard CTAB DNA extraction method. Then DNA purification and PCR amplifications were carried out. The genetic variability and diversity among genotypes was examined by assessing the scoring of the amplified bands by SSR -PCR amplification. Result: Seventeen SSR primers generated 102 polymorphic bands with an average of the six polymorphic bands per primer. The number of alleles per locus ranged from four to nine. The size of amplification product varied for each primer and the range found to be 100bp to 2000bp. The mean polymorphic information content (PIC) value for SSR markers was found to be 0.6335. The value of Jaccard’s similarity coefficient had ranged from 0.07-0.70 with an average value of 0.38. The dendrogram constructed on SSR molecular markers data through the unweighted pair group method with arithmetic averages (UPGMA) method had enabled grouping of the genotypes into thirteen clusters. The results indicate the usefulness of SSR markers in the assessment of genetic variability and diversity among the mutant genotypes of greengram.