Genetic structure of Alhagi (Hedysareae, Fabaceae) populations using ISSR data in Iran

Alhagi Gagnebin (Fabaceae: Hedysareae) is a small genus of shrubs or subshrubs distributed in temperate and tropical regions of Asia, Europe, and Africa. The exact number of Alhagi species in Iran has been disputable. Studies showed that morphology, seed protein, and chromosome characters could not clearly delimitate the species boundaries of the genus. In order to determine species boundaries and the population structure of Alhagi species in Iran, eight labeled inter simple sequence repeat (ISSR) primers were used to screen 22 populations including 110 individuals. STRUCTURE, PCoA and clustering analyses of ISSR data were able to clearly split all populations of Alhagi in Iran into two distinct groups. As the populations A. pseudalhagi and A. maurorum jointly formed a group (A. maurorum complex) segregated from those of Alhagi graecorum. Further analyses of A. maurorum complex showed a significant molecular difference among the studied populations (PhiPT value = 0.213, P = 0.001) as well as a high amount of variability within populations (79%) indicating frequent genetic exchanges. Structure analysis of complex populations (K = 2) showed no distinct genetic pattern related to their geographical distribution. In this study, Alhagi has retrieved the only two species of Alhagi in Iran; A. graecorum and A. maurorum.