Cross-species Transferability of Microsatellite Markers in Sesame Wild Relatives – A Promising Source of Markers for Molecular Applications

Sesamum indicum L., commonly known as sesame, is a diploid member of the family Pedaliaceae, cultivated widely across tropical regions for its oilseed. Sesamum indicum L. subsp. malabaricum (Burm.) Bedigian is the progenitor of the present day cultivated sesame, and domestication events were reported to have occurred in Indian sub-continent. With reference to sesame wild relatives, a few were endemic to Indian Sub-continent while majority of the wild relatives have their origin from African continent. Molecular markers are useful for assessing genetic diversity estimates, in marker assisted selection for breeding programs, and for efficient management of plant genetic resources. We have tested the cross-species transferability for 100 SSR markers from sesame to its wild relatives (10 species). Of these, 21 SSR markers were found to be cross-species transferable, and 15 of them had exhibited polymorphism. 15 polymorphic SSR markers produced a total of 68 alleles with an average number of 4.53 alleles per locus, and the amplicon size ranged between 140 bp and 300 bp. Higher expected heterozygosity (He = 0.61), than observed heterozygosity (Ho), indicates their predominantly self-pollinated nature. However, the occurrence of heterozygosity underscores the presence of cross-pollination to some extent. Hence, this corroborates with the categorization of sesame as often-cross-pollinated crop. A UPGMA-based dendrogram was constructed which grouped the 14 accessions into two major clusters. Parallelly, scanning electron microscopic image profiles for the seeds of these 10 sesame wild relatives were compared with the clustering pattern derived using SSR markers and found corroborative.