Genetic diversity and population structure of the endangered argan tree (Argania spinosa L. Skeels) in morocco as revealed by SSR markers: Implication for conservation

Abstract

Argania spinosa L. is an endangered tree of great socio-economic and ecological value in Morocco. In this study, thirteen nuclear SSR primer pairs were used to assess the genetic diversity and structure of 24 natural populations, including 240 individuals, representing 4 geographic regions. A total of 245 alleles were detected with an average of 18.5 per locus ranging from 6 to 35. The polymorphism information content (PIC) was in the range of (0.487-0.936) showing the good discriminating power of the SSR loci used. The observed and the expected heterozygosity across all populations and loci ranged from 0.372 to 0.777 and from 0.486 to 0.735, respectively. Analysis of molecular variance (AMOVA) revealed that the main variation existed within populations (78%) rather than among populations (12%). The Mantel test displayed no significant correlation between the geographic distance and the genetic distances for all populations. The STRUCTURE analysis and UPGMA clustering grouped 240 samples from 24 populations into two subgroups. Implications of the results for argan tree conservations are also discussed in this paper.