Diversity and spatial genetic structure of natural Moroccan Quercus susber L. assessed by ISSR markers for conservation

Morocco is one of the most important regions of the world in terms of Quercus suber L. number and variation. This species is in decline due to several factors, which can lead to permanent loss of this resource. It would be essential to evaluate the genetic diversity in order to conserve maximum genetic variability of this species. The genetic diversity and differentiation of 16 sites from five regions representing the entire range of Moroccan Cork Oak were assessed. Twenty-three ISSR primers used generated 985 polymorphic fragments with an average of 42.8 bands per primer and showed 100% of polymorphism. The 173 individuals revealed a moderate level of genetic diversity at species level (I = 0.27, He = 0.161). The AMOVA showed that the highest level of diversity occurred within populations (64%), this was also confirmed by the coefficient of differentiation (Gst = 0.47). The estimated gene flow (Nm = 0.56) and the Mantel test revealed a significant correlation between geographic and genetic diversity (r = 0.266; p = 0.001). This genetic structure was further shown by the topology of the UPGMA, sPCA and STRUCTURE analysis. In addition, a core collection of 34 genotypes was established representing the essential diversity detected. This research advocates populations and individuals to preserve in order to improve and conserve this resource in the future.