Characterization of NPR1 Genes from Norton and Cabernet Sauvignon Grapevine

Non-expressor of pathogenesis-related genes 1 (NPR1) plays a significant role in the defense responses of plants to pathogens by regulating the expression of defense-related genes. In the present study, we isolated two NPR1 genes from Vitis aestivalis cv. Norton and Vitis vinifera cv. Cabernet Sauvignon, which were referred to as VaNPR1.1 and VvNPR1. 1-CS, respectively. They encode a protein of 584 amino acids with a predicted molecular weight of 64.8 kDa and a theoretical isoelectric point (pI) of 5.74. The predicted amino acid sequences of VaNPR1.1 and VvNPR1.1-CS differ by only one amino acid. Over-expression of VaNPR1.1 gene in Arabidopsis npr1-1 mutant plants restores the transcriptional expression of AtPR-1 gene, though not to the full scale. This result demonstrated that a grapevine VaNPR1.1 possesses a similar function to the Arabidopsis NPR1 in the regulation of defense-related genes. Over-expression of VaNPR1.1 in transgenic Arabidopsis plant increased tolerance to salinity, but had no effect on the drought tolerance. We conclude that VaNPR1.1 is a functional ortholog of AtNPR1 and also involved in grapevine's response to the salt stress.