Genetic diversity and population structure analysis of Ethiopian bread wheat (Triticum eastivum L.) germplasm using SSR markers

Background : Bread wheat, belonging to the most diverse and important family Poaceae in the plant kingdom, produces crucial edible grains. Ethiopia has been considered as a center of diversity and the second center of bread wheat domestication. Genetic diversity and population structure analyses in the Ethiopian bread wheat germplasm have enormous importance in enhancing breeding and sustainable conservation. Methodology : 96 bread wheat germplasm were gathered from Kulumsa and Adet Research Centers, Ethiopia. The samples were taken to the ICARDA-BIGMP, Cairo, Egypt and grown at the green house, after two weeks leaf samples were collected per plant, and taken to the laboratory for DNA extraction. Data were analyzed using PowerMarker ver. 3.25, NJ, UPGMA, Structure, ver.2.3.4, and AMOVA. Results: Genetic diversity and population structure were estimated across 96 germplasm using 7 polymorphic and informative SSRs. Varied values of diversity indices were observed across chromosomes and genomes. Higher mean values of MAF (0.67), PIC (0.34), and Nei's gene diversity (Gd) (0.36), and values of Gd (0.41) and PPL (87.28%) were signifying the presence of high genetic diversity within and among populations, respectively. AMOVA showed highly significant population differentiation for 98% variation within population letting only 2% significant variation among populations. The Structure analysis showed four populations (COV, EBWNVT, EBWYT, and EBWAT), while the UPGMA revealed 3 main population clusters, in which the EBWYT and EBWAT were the 2 sub-clusters. The NJ analysis and PCoA across 96 germplasm revealed three main clusters in each the germplasm were found inter-mixed irrespective of their breeding history and evolution likely to the Clumpak result, signifying the presence of higher admixture due to the existence of historical exchanges of seeds through informal system involving regional and nationwide farming communities in Ethiopia. Conclusions: Sustainable utilization and conservation of rich Ethiopian bread wheat genetic resource is an irreplaceable means to cope up the recurrent climate changes and biotic stresses happening wide, and thereby able to meet the demand of bread wheat productivity for the ever-growing human population.