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.
Tetraclinis articulata (Vahl) Masters is one of Morocco's most important forest species. It is also found occasionally in Malta and Spain, showing significant adaptability to different bio-climatic conditions. However, the species is being affected by anthropogenic fragmentation, logging and neglect from authorities, which could lead to the irretrievable loss of this resource. In this study, the genetic diversity and genetic structure of ten Moroccan populations of T. articulata were assessed. Fifteen Inter-Simple Sequence Repeat (ISSR) markers were used. These generated 271 polymorphic fragments with an average of 18.06 per primer and showed 79.59% of polymorphism. The 129 individuals revealed a high level of genetic diversity (Hs = 0.221; Ht = 0.254) and 85% of genetic variation within populations. However, the genetic differentiation level was low (Gst = 0.13), which is consistent with the lack of correlation between genetic and geographic distances revealed by the Mantel test, resulting in a high level of gene flow (Nm = 3.294). Based on PCoA and neighbour-joining methods, the ten populations clustered under the effect of continental and marine climates. Compared with other conifers, the current genetic diversity and the pattern of T. articulata population structure indicate an important gene pool requiring efficient conservation strategies.
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