Diversity and relationships in tetraploid wheats(AABB Genome) of Ethiopia assessed by RAPD

Twenty-five tetraploid wheat landraces and 15 improved durum cultivars were used to study the diversity and relationships within and among tetraploid species and regions of origin, and improved cultivars. Thirty-one polymorphic bands produced by two RAPD marker primers were used for the analysis. The mean Shannon diversity index (H) for landrace collections and improved cultivars were 0.34 and 0.23, respectively. Among the four species studied, T. durum was with the highest (0.32) diversity value whereas T. polonicum with the lowest (0.26). Similarly, Wello region collections revealed highest (0.27) tetraploid wheat diversity while Shewa collections, the lowest (0.22). The within species and regions variations were 81.4% and 72.2%, respectively. It suggests the need to collect more wheat germplasm samples within regions. Cluster analysis for all genotypes grouped mainly into landrace collections and improved cultivars. Clustering of landrace genotypes resulted in four groups mainly according to their regions of origin. However, it failed to group on the basis of their species. It suggests the presence of more genetic differentiation among regions than species. The lowest (0.00) and highest (0.73) genetic distances were observed between Wet1224 and Wet1570, and Wet1650 and Bae1117, respectively. The between species genetic distance was lowest (0.016) between T. polonicum and T. turgidum, but highest (0.051) between T. aethiopicum and T. durum. Clustering of improved durum cultivars formed four groups at 80% similarity coefficient. The lowest genetic distance (0.032) was observed between cultivars Ld357 and boohai, foka and Kilinto, and Tob66 and DZ 1640. The highest distance (0.34) was between Asassa and Bichena, Asassa and Boohai, and Bichena and Ude cultivars. The average distance within improved durum cultivars was 0.157. It indicates that all the 15 improved cultivars are relatively similar. Little correlation was observed between groups formed by cultivars and common parentage.