Evaluation of Genetic Diversity in Sorghum Genotypes via Simple Sequence Repeat (SSR) Markers

This study aimed to evaluate the genetic diversity of 20 sorghum [Sorghum bicolor (L.) Moench] genotypes via simple sequence repeat (SSR) markers, with a focus on identifying drought-tolerant varieties. Leaf samples were collected from three-week-old seedlings, and genomic DNA was extracted via the CTAB method, a widely recognized protocol for obtaining high-quality DNA. The DNA samples were quantified to ensure consistent template concentrations for amplification via 25 SSR primers. PCR amplification was performed, followed by agarose gel electrophoresis to separate and visualize the SSR band patterns, which were then recorded in a binary matrix format on the basis of the presence or absence of bands. Among the SSR primers used, nine were polymorphic, generating 13 scorable markers, highlighting the genetic variability among the genotypes. The polymorphic information content (PIC) values ranged across the SSR loci, with the Xtxp145 locus exhibiting the highest PIC value of 0.998, indicating its high discriminatory power and informativeness in differentiating between genotypes. Genetic similarity indices were calculated via Jaccard's similarity coefficient [1], and the data were subjected to cluster analysis via the unweighted pair group method with arithmetic mean (UPGMA) method. The resulting dendrogram grouped the genotypes into seven main clusters at a 50% similarity threshold, underscoring the genetic diversity present within the sorghum genotypes studied. Cluster I contained a single genotype, SVD-1272R, whereas, Cluster II included seven genotypes with subcluster formation. Cluster III comprised one ungrouped genotype, SPV-486. Cluster IV included eight genotypes, whereas Clusters V, VI, and VII each contained a single ungrouped genotype. This dendrogram illustrates the genetic diversity and relationships among the sorghum genotypes on the basis of similarity indices. The findings of this study confirmed the efficacy of SSR markers in assessing genetic diversity and emphasized their potential utility in breeding programs aimed at improving drought tolerance.