Isolation and functional validation of the VvZFP11 promoter associated with a signaling molecule and powdery mildew responses in grapevine

Abstract

• Overexpression of VvZFP11 improves powdery mildew resistance in grapes. • The PME element of the VvZFP11 gene is essential for its function. • The VvZFP11 gene enables plants to acquire resistance by affecting the salicylic acid signaling pathway. VvZFP11 is up-regulated by powdery mildew (PM), methyl jasmonate (MeJA), and salicylic acid (SA) treatment, yet the underlying transcriptional regulatory mechanism remains unclear. Here, we demonstrate that a powdery mildew response element (PME) in the VvZFP11 promoter is important for countering the challenge to grapevine from PM, in which the defensive and stress response element (GTAAGGAAAC) is critical for specific responsiveness to SA, MeJA, and PM. Analysis of VvZFP11 promoter activity showed that VvZFP11 can activate GUS gene expression. SA induced VvZFP11 ’s expression, while VvZFP11 responded swiftly to PM. Analysis of cis- acting elements revealed that VvZFP11 contained diverse elements related to plant responses to biotic/abiotic stresses. Further experiments revealed PME in the VvZFP11 promoter was crucial for responding to PM. The PME and MV35S core promoters were fused and constructed into a single promoter, then inserted directionally into VvZFP11-GUS's upstream region to obtain a fusion construct. VvZFP11 transcript levels were significantly suppressed in transgenic plants with mutant PEM element after their inoculation with PM (based on Fig. 6). RT-qPCR results indicated the genes AtPR1, AtNPR1, AtPDF1.2 , and AtCOI , these related to SA and MeJA, were down-regulated in transgenic plants. The results also confirmed the defensive and stress response element in PME is a key component for the VvZFP11 promoter's function and that VvZFP11 enables plants to gain resistance to PM via the SA pathways.