Development of an EMS-Induced Sesame Mutant Population for Target Induced Local Lesions in Genomes (TILLING)

Cultivated sesame is a diploid species (Sesame indicum L., 2n = 2x = 26) with a relatively small nuclear genome size (1C = ~360 x 10⁶ bp) consisting of a considerably low proportion of repetitive sequences. Sesame has a relatively short lifecycle producing mature seeds within 80 days after planting. Furthermore, a single sesame plant can easily produce many seeds (over 1,000 seeds per plant). All these features make sesame a good oilseed crop model for genome and genetic studies. Recently, the sesame genome has been successfully sequenced; but there were no mutant resources publically available yet. We have screened the entire U.S. sesame germplasm collection (1,232 accessions) for seed weight, oil content and fatty acid composition by NMR and GC analysis. Variability in seed weight, oil content, and fatty acid composition were quantified from the collection. An elite line was selected from the screening, purified for two generations, and used for EMS-induced mutagenesis. A mutant population was thus generated. Significant plant morphological changes (such as plant height, leaf shape and color, capsule shape, and maturity) were observed from the M₂ population in the green house. Chemical analysis is being conducted on the seed quality traits. This mutant population will be useful for both genome research (such as TILLING) and sesame improvement (such as seed quality) in breeding programs. The results from this mutant population will be presented.