Evaluation of genetic diversity in two Morus species in Syria, using molecular markers ISSR and SSR

In Syria, there are ancient wild, and cultivated mulberry trees, traditionally used to feed the silkworm Bombyx mori L., and cultivated for their edible fruits. Evaluating genetic relationships is imperative for the identification, conservation, and improvement of mulberry germplasm. The present study addresses the use of inter simple sequence repeat (ISSR) and simple sequence repeat (SSR) markers to estimate genetic diversity within and between two different mulberry species (49 genotypes of Morus nigra cultivar. El-Shami) and (8 genotypes of Morus alba) from different regions of Syria (Al-Qunaitra, Tartus and Latakia). Fifteen ISSR primers and six SSR primer pairs were used in the analysis. Overall, genetic diversity within M. alba and M. nigra was low (0.22). The genetic distance between the two species (M. nigra and M. alba) was higher (0.72) than that within the species (0.3). A dendrogram based on SSR and ISSR results showed the clustering of samples according to the species and to their geographic collection sites. The level of polymorphism detected between samples using the ISSR marker (90.31%) was higher than that detected with SSR marker (68.05%). The genotypes collected from Al-Qunaitra were very similar as the coefficient of genetic distance -CGD- was less than 0.1, while genotypes from Latakia were more distant (CGD is 0.33). In general, the level of genetic diversity between the analyzed genotypes of M. nigra cv. El-Shami was lower than between the samples of M. alba.