Abstract:

Sesame (Sesamum indicum L.), an important oil-yielding plant, is one of the most ancient crops in tropical and subtropical areas. Despite its nutritional value and importance, the research on sesame has been scarce. In this study genetic relationships among 134 Chinese sesames, 41 alien sesames, and 17 improved cultivars were analysed using SRAP and EST-SSR markers. Large genetic variability was found within all the germplasm collection. A total of 270 SRAP markers were recorded using 31 primer combinations, each primer detected 5.45 loci; While 25 pairs of SSR amplified 136 loci, each primer detected 3.04 loci. Mantel test revealed that the relation of genetic similarity matrix between SRAP and SSR was significant (r=0.7864, t=5.2571, P<0.01) for 192 species, so the UPGMA dendrogram was set up based on the integrated data of SRAP and SSR. The 192 accessions were grouped into three robust clusters, and cluster Ⅰ consisted of six groups, which was not revealed any association between genotype and geographical origin. Accessions came from one region were distributed throughout the dendrogram. The results revealed by the genetic distance and Shannor-weaver index of sesame germplasm resources from different regions that the genetic diversity of sesame was high, and in our nation the southern was higher than the others. We presumed that the sesame species was introduced to the Southern China firstly, of course it needs other evidence to be substantiated. The cluster result suggests that there was a considerable gene flow among different regions. So when we choose the parents in sesame breeding focusing on the genetic relationships is a good strategy.

Key words: Sesamum indicum L., SRAP, EST-SSR, Genetic diversity