Efficiency of Agrobacterium tumefaciens-mediated transformation of tobacco (Nicotiana tabacum L.) with rice OsNAC6 gene

Abstract

Crop improvement by genetic engineering requires efficient plant regeneration derived from cultured cells or tissues. The success of cell or tissue culture regeneration depends on reliable explant source. In this study, three different types of explant (callus, stem, and leaf) of tobacco (Nicotiana tabacum L.) were evaluated to determine the most effective explant source for Osnac6 gene transformation. OsNAC6 encodes a transcription factor belonged to NAC transcription factor family in rice (Oryza sativa L.). OsNAC6 transcription factor has been reported in some studies to confer tolerance to drought stress. Agrobacterium tumefaciens strain EHA 105 harboring pC1305 plasmid containing the OsNAC6 gene driven by CaMV 35S promoter (pARNAC6) was used for transformation. The T-DNA contains hygromycin phosphotransferase (hpt) gene as a selectable marker. PCR confirmed the presence of the hpt gene in the T0 generation of the transformed tobacco plants. The PCR result showed that a total of 50 tobacco plants were positive for hpt gene which 18, 20, and 12 of them derived from callus, stem, and leaf explants respectively. The highest transformation efficiency was obtained by using the stem as explant material, i.e. 17%. Meanwhile, the obtained transformation efficiency by using callus and leaf was 15% and 10% respectively.