Abstract
In many arid and semi-arid regions, P. juliflora has an enormous importance in the protection of this fragile environment, and of a very economical importance. In those areas, P. juliflora is regarded as a renewable natural resource of multiple uses, where they are used in the production of wood for many purposes and for fuel. This research carried out many studies on the genetic structure of some P. julifloragenotypes that exist in Saudi Arabia. This study presented the characterization of P. juliflora genotypes using 14 polymorphic microsatellite markers. SSR markers showed that the number of alleles varied from one to 5. The analysis of SSR markers has been shown to have most abundant motif of dinucleotide AG/CT followed by mononucleotide A/T. The genetic cluster tree, using UPGMA program, divided the genotypes to 4 main groups at similarity coefficient between 0.56 and 0.91. In addition, two restriction enzymes, Bam-HI and Eco-RI have been used in conjunction with six SSR primers to obtain more distinguishable differences. Genetic cluster tree for similarity coefficients of SSR primers using only Eco-R1 enzyme showed that the enzyme gave very clear genetic variation among the genotypes under study. However, the enzyme BamH1could be useful in identifying mesquite genotypes had free or low content of histamine.