Genetic Characterization and Population Structure of Mozambique’s Sesame (Sesamum indicum L.) Accessions Using DArTseq-Derived SNP Markers

Abstract

Background/Objective: Sesame (Sesamum indicum L.) is a nutritionally and economically important oilseed crop that is grown predominantly by smallholder farmers in Mozambique. However, its breeding process is constrained by a limited understanding of the genetic diversity in sesame germplasm. Therefore, this study determined the genetic diversity and population structure of a panel of 109 sesame accessions from Instituto de Investigação Agrária de Mocambique (IIAM) using DArTseq SNPs. Methods: The generated 14,763 SNPs were filtered, retaining 11,502 high-quality SNPs for this study. Results: Overall genetic diversity was moderate (mean He = 0.30, Ho = 0.30, MAF = 0.21, PIC = 0.25). Population structure analysis using sparse non-negative matrix factorization identified eight subpopulations, consistent with principal component analysis implemented via the Latent factor mixed model. Discriminant analysis of principal components (DAPC) and Ward’s hierarchical clustering based on Nei’s distance resolved the same eight clusters, although DAPC revealed overlap among clusters, consistent with extensive admixture. Analysis of molecular variance showed that 85.85% of total molecular variation was within subpopulations and 14.15% among the subpopulations. Pairwise fixation indices (ranging from 0.02 to 0.10) identified divergent subpopulations 7 and 1 as suitable candidates for hybridization. Within subpopulations, observed heterozygosity exceeded expected heterozygosity, likely reflecting residual heterozygosity in sesame landraces, admixture, reverse Wahlund effect and scoring of paralogs as heterozygous SNPs. Conclusions: Overall, this study provided insights into sesame’s genetic diversity in Mozambique, contributing to germplasm conservation and informed parental selection.