Overexpression of Vitis vinifera VvbZIP60 enhances Arabidopsis resistance to powdery mildew via the salicylic acid signaling pathway

Powdery mildew is a fungus that causes major losses in grape production worldwide. Recent studies demonstrate bZIP transcription factors (TFs) play an important role in plant defense against fungal pathogens. To investigate whether one or more bZIP TFs is involved in the common grapevine’s defense against powdery mildew, which could provide candidate genes for breeding powdery mildew-resistant grape plants, we isolated its VvbZIP60 gene and analyzed its functional role in plants against powdery mildew. Amino acid sequence alignment and phylogenetic analysis indicated that VvbZIP60 is a U member of the bZIP gene family and is similar to AtbZIP60 of Arabidopsis. The gene expression profile of the ‘Jing Xiu’ variety of grape (Vitis vinifera) showed that the VvbZIP60 transcript accumulated in various tissues (especially leaves) and could quickly accumulate when this plant was treated with exogenous pathogen (PA),1 salicylic acid (SA) and jasmonic acid (JA). VvbZIP60 was found localized to the nucleus and has transcriptional activation in yeast. Crucially, overexpression of VvbZIP60 increased Arabidopsis resistance to powdery mildew. Transgenic plants accumulated SA and up-regulated their expression of the pathogenesis related 1 (PR1) gene involved in the SA-signaling pathway. Taken together, these results show that VvbZIP60 is a positive regulator of resistance to fungal disease and contributes importantly to SA signaling against powdery mildew.