Molecular analysis of over-expression of NPR1 gene in putative transgenics of Brassica juncea plants

Brassica accounts for nearly 27% of vegetable oil requirements of India. Its production however is constrained by Alternaria blight ( Alternaria brassicae). The absence of resistance genes within crossable germplasm of Brassica juncea necessitates the use of genetic engineering strategies to develop genetic resistance against this pathogen. Potential of regulatory genes for developing fungi- and bacteria-resistant transgenic plants has been demonstrated in Arabidopsis and other plants, one such regulatory gene being NPR1. Brassica juncea NPR1 (BjNPR1) gene was over-expressed in Brassica juncea. Transformation of hypocotyls of B. juncea var. Varuna with the BjNPR1 gene under the control of constitutive CaMV35S promoter using Agrobacterium tumefaciens strain EHA105 resulted in about 1.4% of transformation efficiency. The integration of BjNPR1 into the plant genome was confirmed by PCR using NPTII primers, in which 90% of the plants analyzed were found to be PCR positive. Moreover, over-expression of the BjNPR1 transcript was shown in 60% of the total plants analyzed by RT-PCR using NPR1 primers.