SSR- Based Genetic Diversity Assessment in Tetraploid and Hexaploid Wheat Populations.

Molecular analysis for a set of hexaploid (Triticum aestvium) and tetraploid ((Triticum durum) wheat cultivars was investigated by applying 11 SSR primers set. The plant materials consisted of 45 genotypes 15 of which were Triticum aestivum and  30 of T. durum obtained from four different regions Egypt, Greece, Cyprus and Italy. PCR products were separated on a 6% denaturing polyacrylamide gel electrophoresis and produced a total of 3840 DNA fragments which were used for the molecular analysis. The estimated parameters computed by POPGENE (Version 1.32) within the two population indicated that the Nei’s genetic diversity (H) was 0.2827, and the Shannon's Information index (I) was 0.4533 with standard deviation  ± 0.0699  and ± 0.0852  respectively. The analysis of population structure revealed that genetic diversity within populations (HS=0.2761) represented 97.7% of the total genetic diversity (HT=0.2827). The proportion of the total genetic diversity that was attributed to the population differentiation was low (GST=0.0233) within population.  ANOSIM (ANalysis Of Similarities), results showed that R was equal to 0.9048 (P<0.0001) indicated that all the most similar samples of genotypes are within the same population. The wheat varieties from the four distinct regions were clustered according to SSR data into two main clusters, durum wheat varieties and bread wheat varieties, the principal coordinate analysis (PCOORDA) validated the results of the dendrogram. This study showed that the two populations still had moderate considerable level of genetic diversity and show little genetic differentiation among them. Understanding genetic variation within and between populations is essential for the establishment of an effective breeding programs concerning the intraspecific and interspecific hybridization.

Keywords: ANOSIM, Genetic diversity, bread wheat, durum wheat, SSR markers, POPGENE.