Molecular Diversity Studies and Core Development in Sesame Germplasm (Sesamum indicum L.) Using SSR Markers

Sesame (Sesamum indicum L.), an ancient oilseed crop being cultivated across geographical locations in the tropics, is known for its high-quality oil with a longer shelf life. India, being the center of diversity for this crop, understanding the genetic variability of sesame germplasm being conserved in the national Genebank (NGB) of ICAR-NBPGR, will help identify genotypes for its potential use in broadening the genetic base of the cultivars for sesame crop improvement. We report here the molecular diversity analysis performed using SSR markers on a set of 2,496 sesame germplasm. Hence, the derived data was also subjected to population structure analysis, and a molecular core was generated to assess its phenotypic variability. Parallelly, they were phenotypically characterized for important qualitative and quantitative traits as per the standard descriptor developed by IPGRI, and accessions exhibiting desirable traits were identified. The sesame germplasm used in our study represents collections from 17 countries across the globe and 26 states in India. A total of 140 alleles were obtained using seven polymorphic SSR markers selected from an initial screening comprising 43 SSR markers. The observed heterozygosity was less than the expected heterozygosity since it is a self-pollinated crop (up to 35% outcrossing is reported, categorized as often cross-pollinated). The molecular diversity analysis grouped 2496 accessions into six clusters, while the population structure analysis grouped them into three major clusters or populations. A molecular core developed using the PowerCore software identified 196 accessions, representing all the alleles from the entire 2496 accessions, that can be utilized in breeding programs after phenotypic validation. This study contributes to genetic diversity assessment for sesame germplasm, identifying genetically diverse accessions, and establishing a core set that encapsulates the genetic variability of the sesame germplasm collection. These findings hold relevance for addressing agricultural challenges and enhancing the resilience and productivity of sesame crops in various environmental conditions.