Argan Tree is well known for its precious oil extracted from its seeds particularly used for the nutritional and cosmetic benefits. Because of the high international demand, the argan tree suffers from overexploitation and its cultivation is rare. Thus, the assessment of the genetic variation of this endemic tree is critically important for designing conservation strategies. In the present study and for the first time, genetic diversity of the global natural distribution of argan tree ( L.) in Morocco was assessed. Four IRAP (inter-retrotransposon amplified polymorphism) primer combinations and seven ISSR (inter-simple sequence repeat) primers amplified 164 and 248 scorable polymorphic bands respectively. Polymorphic information content (PIC = 0.27), resolving power (Rp = 15) and marker index (MI = 10.81) generated by IRAP primer combinations were almost identical to those generated by ISSR primers (PIC = 0.27, Rp = 9.16 and MI = 12). AMOVA analysis showed that 49% of the genetic variation was partitioned within populations which is supported by Nei's genetic differentiation (Gst = 0.5391) and the overall estimate of gene flow (Nm) being 0.4274. The STRUCTURE analysis, PCoA (principal coordinate analysis) and UPGMA (unweighted pair-group method with arithmetic mean) based on the combined data matrices of IRAP and ISSR divided the 240 argan genotypes into two groups. The strong differentiation observed might be due to the geographical distribution of argan tree. Our results provide crucial insight for genetic conservation programs of this genetic resource.

Drought and desertification are the major environmental constraints facing the Sahelian agro-ecosystems for decades. Assessing genetic diversity of native tree species is critical to assist ecosystems restoration efforts. Here we describe genetic diversity and structure of seven Balanites aegyptiaca L. natural populations distributed across the Sahelian-Saharan zone of Mauritania using 16 polymorphic ISSR primers. These generated 505 polymorphic bands. Polymorphism information content (PIC) varied from (0.13–0.29) with an average 0.23, marker index (MI) averaged 7.3 (range 3.3–10.3) and resolving power (RP) ranged from (4.53–14.6) with an average 9.9. The number of observed alleles (Na) ranged from (0.62–1.39), Effective number of alleles (Ne) varied from (1.26–1.37), Shannon’s information index (I) ranged from (0.25–0.36). AMOVA analysis showed that 80% of the genetic variation was fined within populations, which is supported by a low level of genetic differentiation between population (GST = 0.21) and an overall estimate of gene flow among populations (Nm = 1.9). The dendrogram based on Jaccard's similarity coefficient and the structure analysis divided the seven populations into two main clusters in which two populations from the Saharan zone were grouped. Our results provide baseline data for genetic conservation programs of this Sahelian neglected crop and with an important econ-ecological role.

The argan tree (Argania spinosa L. Skeels, Sapotaceae) is a genetic resource endemic in Morocco. Genetic diversity within and among 13 populations (130 genotypes) of argan tree was studied using AFLP markers. Having checked twenty combinations of labeled primers for regular genomes (500-6000 Mb) (EcoRI+3/ MseI+3 selective bases) and for small genome (50-500 Mb) (EcoRI+2/MseI+3 selective bases), we selected four combinations specific for regular genome able to produce a relatively high polymorphism and a low error rate (0.12 %). A total of 477 unambiguous peaks were amplified ranging from 70 to 500 bp. The average polymorphism information content (PICAVG) value ranged from 0.19 to 0.23. Marker index (MI) and resolving power (RP) varied from 21.23 to 28.82 and 27.63 to 44.92, respectively. Analysis of molecular variance (AMOVA) showed that 19 % of the genetic variation was partitioned among populations and 81 % of the genetic variation was within populations. This was confirmed by the coefficient of gene differentiation between populations (Gst=0.22), and gene flow was estimated to 1.709. The STRUCTURE analysis, principal coordinate analysis (PCoA) and Unweighyhed Pair Group Method with Arithmetic Mean (UPGMA) revealed that populations of A. spinosa were clustered into three genetic groups. The present results can be explored in the design of in situ and ex situ conservation and management programs.

Morocco is one of the most important regions of the world in terms of 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; = 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.

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.