Genetic diversity and gene-pool of Medicago polymorpha L. based on retrotransposon-based markers

The genus Medicago L. (Fabaceae) comprises approximately 87 different species of herbs and shrubs widespread from the Mediterranean to central Asia. Medicago polymorpha is a herbaceous legume that can be a useful pasture plant, in particular, in regions with a Mediterranean climate. It had aroused great interest due to high nutritious quality, highly palatability and N-fixing plan in neutral soil. There is no information on its population genetic structure, genetic diversity, and morphological variability in Iran. Due to the medicinal importance of this species, a genetic variability and populations’ structure study is performed studying 15 geographical populations of Medicago polymorpha. Therefore, we used six inter-retrotransposon amplified polymorphism (IRAP) markers and 15 combined IRAP markers to reveal within and among population genetic diversity in this plant. AMOVA test produced significant genetic difference (PhiPT = 0.46, P = 0.010) among the studied populations and also revealed that, 66% of total genetic variability was due to within population diversity while, 34% was due to among population genetic differentiation. Mantel test showed positive significant correlation between genetic distance and geographical distance of the studied populations. STRUCTURE analyses and population assignment test revealed some degree of gene flow among these populations. PCoA plot of populations was in agreement with UPGMA clustering of molecular data. These results indicated that geographical populations of Medicago polymorpha are well differentiated based on (IRAP) markers.