EST-SSR diversity correlated with ecological and genetic factors of wild emmer wheat in Israel

Abstract

The differentiation of genetic diversity was estimated among 15 wild emmer wheat (Triticum dicoccoides) populations of the macrogeographic scale in Israel by 25 EST-SSR markers. A total of 92 EST-SSR alleles were detected, and the number of alleles ranged from 1 to 7 with an average of 3.68 per locus. Allele numbers and the polymorphic information content (PIC)value of EST-SSR loci on the B genome were higher than those on the A genome. The genetic similarity coefficient (GS)varied from 0.189 to 0.966, and all genotypes were clustered into four major groups. The population Mt. Gerizim had the highest genetic variations, whereas the population Beit-Oren had the lowest genetic variations. Most of genetic variance existed within populations was observed based on the coefficient of gene differentiation (F(ST)=0.355). The value of genetic distance (D) between the populations varied from 0.112 to 0.672 with an average of 0.406, and the results of Mantel test(r=0.104, p=0.809) showed that the estimates of genetic distance were geographically independent. The values of Nei's gene diversity (He) and Shannon's information index (I) correlated negatively with the temperature factor: mean January temperature (Tj), whereas they correlated positively with another factor: mean number of Sharav days (Sh). The correlation matrix between He in the EST-SSRs and climatic variables contained 37 significant (pB0.05) correlations. The present study established that T. dicoccoides in Israel had a considerable amount of genetic variations at EST-SSR loci at least partly correlated with ecological factors. These results suggested that EST-SSR diversity is adaptive by natural selection and influenced by both internal and external factors and their interactions.