Asian Journal of Research in Botany

Background: Vigna radiata is a nutritionally important grain legume whose genetic improvement and breeding efficiency depend on accurate assessment of genetic diversity using SSR molecular markers.

Aims: To assess the genetic diversity of mung bean genotypes through the application of SSR markers.

Study Design:  The experiment was conducted using a plot size of 5m x 5m. Seed viability was evaluated through germination tests following mechanical scarification and fungicide treatment.

Place and Duration of the Study: Located in Ibadan, in the southwestern region of Nigeria, the study was carried out between March and June 2025.

Methodology: SSR primers used in this study were selected from previously validated mung bean microsatellite markers developed by (Somta et al., 2009; Saini et al., 2024). and additional legume SSR resources reported by Varshney et al. (2021). Primers were chosen based on their high polymorphism, reproducibility, and broad genome coverage.

Primer sequences were synthesized commercially and validated prior to PCR amplification.

Fifteen mung bean (Vigna radiata) genotypes were sourced from the International Institute of Tropical Agriculture for this study. The experiment was established in a randomized complete block design with three replicates under standard agronomic management. Young leaf tissues were collected for genomic DNA extraction using the CTAB protocol. DNA quality and concentration were assessed by agarose gel electrophoresis and spectrophotometric analysis. Genetic variation was examined using SSR markers through PCR amplification. The resulting amplicons were resolved on agarose gel, and banding patterns were scored in a binary format. Genetic diversity parameters were computed using GenAlEx, and analyses including cluster analysis and AMOVA were performed to evaluate genetic relationships and population structure.

Results: SSR markers revealed a moderate to high level of polymorphism among the mung bean genotypes, with three to six alleles detected per locus. Polymorphic information content (PIC) values ranging from 0.45 to 0.82 indicate that most markers were highly informative for detecting genetic variation, while allele frequency differences further confirm substantial diversity within the population. Genetic similarity coefficients showed varying degrees of relatedness, highlighting the presence of both closely related and genetically divergent lines suitable for breeding. Cluster analysis grouped the genotypes into three distinct clusters, reflecting clear differences in genetic background and a structured patternof variability. Analysis of molecular variance (AMOVA) showed that 68% of the genetic variation occurred within populations and 32% among populations, with a fixation index (FST = 0.32) indicating moderate to high genetic differentiation. Overall, the observed polymorphism, genetic divergence, and population structure demonstrate significant variability and strong potential for selecting diverse parental lines to enhance breeding efficiency.

Conclusion: The study demonstrates substantial genetic diversity among mung bean genotypes, with high levels of polymorphism and allelic variation confirming the effectiveness of SSR markers for genetic characterization. The predominance of within-population variability, coupled with moderate differentiation among populations, highlights strong potential for targeted selection and hybridization, particularly through the use of parental lines from distinct genetic clusters to enhance heterosis. Overall, these findings provide valuable insights into the genetic structure of mung bean and emphasize the importance of molecular tools in breeding and germplasm conservation efforts.