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.

Inter simple sequence repeat markers to assess genetic diversity of the desert date (Balanites aegyptiaca Del.) for Sahelian ecosystem restoration.

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.

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.

Assessment of genetic diversity and population structure of an endemic Moroccan tree (Argania spinosa L.) based in IRAP and ISSR markers and implications for conservation.

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 (Argania spinosa 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.