Analysis of Genetic Diversity And Population Structure Study In Bread Wheat (Triticum Aestivum) Recombinant Inbred Lines And Few Commercial Cultivars Using Simple Sequence Repeats (SSRs) Markers

Abstract

Wheat is one of the most important cereal crops to sustain food security worldwide. Bread wheat takes the lead in production and economic significance among other species of wheat. Despite many genetic diversity study of bread wheat using varieties of techniques in Ethiopia, there is still a need for continual researching of the species in order to meet the high demand rising with population. One way of exploring potential bread wheat germplasms with wide genetic diversity is engaging dif erent breeding materials in the research. So far to the best extent of available data, genetic diversity of bread wheat RILs has not been done with microsatellite markers in Ethiopia. Therefore, the present study was targeted to investigate the extent of genetic diversity and population structure of 91 bread wheat RILs and few Cultivars using 10 microsatellite markers. Modified CTAB DNA extraction method was used. The DNA of each genotype was extracted from its respective young leaves grown in plastic pot for 21 days in green house. The quality and quantity of the extracted DNA was checked by agarose gel electrophoresis and nanodrop spectrophotometer respectively. The condition for the PCR was initial denaturation held at 94℃ for 4 min, 40 cycles of denaturation for 1 min at 94℃, primer annealing temperature varying for each marker for 1 min, extension at 72℃ for 1:30 min and final extension at 72 ℃ for 10 min. Dif erent software applications were employed to score and analyze the data output. The SSR markers used were highly polymorphic, resulting in 68 alleles. The polymorphic information content of the loci ranged from 0.67 to 0.86 with an overall mean of 0.78. The population showed high gene diversity (0.81), expected heterozygosity (0.81), Shannon’s information index (1.61) and percent of polymorphic loci (100%). Analysis of molecular variance (AMOVA) revealed the presence of a genetic dif erentiation (PhiPT: 0.039) in which 96% of the total genetic variation was accounted by the within populations variation, leaving 4% for the dif erentiation among populations genetic variation. Population of commercial cultivar to HRWSN showed the highest pairwise genetic dif erentiation and Nei’s genetic distance while the population of ISEPTON to HRWSN resulted in the lowest pairwise genetic dif erentiation and Nei’s genetic distance. Clustering did not sharply grouped the recombinant inbred lines and few commercial cultivars according to their source of breeding material likely due to the presence of high gene flow (Nm = 6.2). STRUCTURE analysis confirmed the two sub-groups with greater degree of genetic admixture. All the bread wheat populations showed high gene diversity indicating the relevance of the respective breeding material for studies related to bread wheat genetic analysis. In this study HRWSN bread wheat collections showed relatively high gene diversity, indicating that these breeding materials could be potential bread wheat recombinant inbred lines and few commercial cultivars sources, and hence future studies and conservation plans shall largely include these