Using two retrotransposon-based marker systems (SRAP and REMAP) for genetic diversity analysis of Moroccan Argan tree

The Argania is an endemic genetic resource in Morocco holding an important ecological and socio-economical benefit. However, overgrazing and overharvesting lead to a serious downturn in the number of trees. To characterize genetic diversity within and among 24 populations, represented by 240 argan trees, four combinations of SRAP primers and eight combinations of REMAP primers were used. A total of 338 REMAP and 146 SRAP markers were amplified with a polymorphism of 100%. The average polymorphism information content value was 0.20 and 0.17 for SRAP and REMAP markers, respectively. The analysis of molecular variance showed that 26% of the genetic variation was partitioned among populations. The coefficient of gene differentiation was 0.2875 and gene flow was 1.2391. The average parameter diversity was: observed number of alleles (Na)=0.729, effective number of alleles (Ne)=1.131, Shannon's information index (I)=1.143; Nei's gene diversity (H)=0.093 and Percentage of Polymorphic Loci=35.68. The STRUCTURE and principal coordinate analysis revealed that the Argania spinosa L. populations were aggregated into 2 genetic groups. To detect outlier, baysecan software was used and 21 were detected (7 under selection, 14 under balancing selection) presenting posterior probability higher than 0.79. The current results can be explored in the design of management programs and to comprehend the adaptation mechanism of Argan tree.