AN IMPROVED METHOD FOR Agrobacterium-MEDIATED TRANSFORMATION OF IRANIAN SESAME (Sesamum indicum L.) CULTIVARS

Sesame (Sesamum indicum L.) is one of the oldest oil seed crops with widespread commercial application. This crop has low selection response to traditional breeding methods. Therefore plant transformation is an alternative approach for the genetic improvement of this crop. In this regard Agrobacterium -mediated transformation can be a method of choice for the routine production of transgenic sesame. In the present study, a successful and reproducible protocol for transformation of Iranian sesame cultivars was described. For this purpose, the effect of different parameters including Agrobacterium tumefaciens strains (GV3101, LBA4404) harboring a binary vector pCAMBIA1304 containing neomycin phosphotransferase (nptII) and b-glucuronidase (GUS) genes, various explants (cotyledon and hypocotyl) and two Iranian sesame cultivars (Yekta and Naztakshakhe) were investigated to develop a protocol with optimum GUS expression. Transformation was verified by PCR on different target genes present in the T-DNA as well as by the determination of GUS activity from the reporter gene. Based on our results cotyledon has higher regeneration and transformation efficiency compared to hypocotyl and LBA4404 Agrobacterium strain has higher transformation efficiency than GV3101. Also, between two sesame cultivars the transformation efficiency of Naztakshakhe was considerably higher than Yekta. Totally we found the rate of transformation in Naztakshakhe using cotyledon explant and LBA4404 strain was 48 percent while in Yekta with hypocotyl and GV3101 was around 10 percent.