Genetic structure and eco-geographical adaptation of garlic landraces (Allium sativum L.) in Iran

In this study we present the genetic analysis of freshly collected\ngarlic landraces (Allium sativum L.) along an eco-geographical transect\nfrom northeastern to western Iran covering seven different provinces\nusing ISSR and RAPD markers. A total of 52 polymorphic loci were\ndetected among 31 landrace populations. The percentage of polymorphic\nbands, the mean effective number of alleles, and the mean gene diversity\nwere 38.82 %, 1.54, and 0.32, respectively. Genetic principal\nco-ordinate analysis and Structure analysis using 52 polymorphic loci\nindicated that the germplasm could be divided into two major groups.\nPrincipal component analysis (PCA), using geographical and environmental\nvariables suggested the role of both geographical and environmental\nadaptation in driving and maintaining genetic differentiation between\nthe major groups. In addition, our results showed that the combination\nof latitude, altitude, and precipitation explains the highest proportion\nof the variance in the PCA of eco-geographical data. This study shows\nthat geographical and environmental factors together created stronger\nand more discrete genetic differentiation than isolation by distance\nalone. These findings emphasize the importance of environmental\nselection in shaping patterns of genetic structure inferred in Iranian\ngarlic germplasm. We suggest that action should be immediately taken for\ncollecting, protecting and evaluating the genetic diversity of garlic\nlandraces before they disappear in Iran.