Analysis of Genetic Diversity and Population Structure of Sesame (Sesamum indicium L.) Germplasm Using Inter Simple Sequence Repeats (ISSRs) Markers

Abstract

Sesame is one of the most important Oily crops to sustain food security worldwide. Sesamum indicium L. takes the lead in production and economic significance among other species of Sesame. Despite many genetic diversity studies of Sesamum indicium L. 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 sesame germplasms with wide genetic diversity is engaging different breeding materials in the research. So far to the best extent of available data, genetic diversity of Sesamum indicium .L has not been done with ISSR markers in Ethiopia. Therefore, the present study was targeted to investigate the extent of genetic diversity and population structure of 93 Sesamum indicium .L using 10 ISSR markers. Modified CTAB method was used for DNA extraction. The quality and quantity of the extracted DNA was checked by agarose gel electrophoresis and Nano drop spectrophotometer, respectively. PCR was performed using 10 ISSR primers. Different software applications were employed to score and analyse the data output. The ISSR markers used were highly polymorphic, resulting in 204 alleles. The polymorphic information content of the loci ranged from 14 to 27 with an overall mean of 20. The population showed high gene diversity (0.23), expected heterozygosity (0.28), Shannon’s information index (0.36) and percent of polymorphic loci (84.80%). Analysis of molecular variance (AMOVA) revealed the presence of a genetic differentiation (PhiPT:0.124) in which 88 % of the total genetic variation was accounted by the within populations variation, leaving 12% for the differentiation among populations genetic variation. Population of Amhara and Oromia showed the highest pairwise genetic differentiation and Nei’s genetic distance while the other population resulted in the moderate pairwise genetic differentiation and Nei’s genetic distance. Clustering did not sharply grouped the sesame according to their source of breeding material likely due to the presence of high gene flow (Nm =3.75). STRUCTURE analysis confirmed two sub-groups with greater degree of genetic admixture. All the sesame populations showed high gene diversity indicating the relevance of the respective breeding material for studies related to sesame genetic analysis. In this study, collections showed relatively high gene diversity, indicating that these breeding materials could be potential sesame sources, and hence future studies and conservation plans shall largely include these breeding materials.