ISSR-Based Genetic Diversity and Structure of Medicago sativa L. Populations from the Aras Basin, a Crossroad of Gene Centers

The Aras Basin, located at the intersection of three major gene centers, represents one of the most important transition zones for the evolution of forage legumes. This study evaluates the genetic diversity and population structure of 74 <i>Medicago sativa</i> genotypes, including wild populations and commercial cultivars, using ISSR markers. The analysis revealed a broad level of genetic variability, reflecting the adaptive potential of alfalfa in this ecologically heterogeneous region. Population structure analyses consistently separated the germplasm into three genetic clusters, demonstrating clear differentiation between wild accessions and registered varieties. Geographical patterns were also evident, with genotypes from western, central, and eastern subregions forming distinct groups. These results highlight the unique genomic composition of alfalfa in the Aras Basin and demonstrate the value of ISSR markers for characterizing multilayered genetic variation in ecological transition zones. The findings provide a complementary genomic perspective that expands existing knowledge of <i>M. sativa</i> diversity and offers useful guidance for breeding programs and genetic resource conservation.