Vitis vinifera VvPUB17 functions as a E3 ubiquitin ligase and enhances powdery mildew resistance via the salicylic acid signaling pathway

BACKGROUND: Powdery mildew affects grapevine growth and development and reduces grapevine fruit yield and quality. Plant U-box (PUB) E3 ubiquitin ligases play important roles in ubiquitin/proteasome-mediated protein degradation during plant development and in the plant defense response. OBJECTIVE: We cloned the VvPUB17 gene from Vitis vinifera and analyzed that VvPUB17 enhanced the resistance of grapevine to powdery mildew through the SA signal pathway. METHODS: Pathogen inoculation of Arabidopsis thaliana and grapevine plants was carried out by the tableting method. Gene expression was analyzed by quantitative real-time PCR. Sequence analysis and in vitro ubiquitination experiments show the structure and characteristics of VvPUB17. Exogenous salicylic acid, methyl jasmonate, ethylene and powdery mildew induced the expression of VvPUB17 in Arabidopsis leaves to verify the resistance of VvPUB17 to powdery mildew. RESULTS: Sequence analysis and in vitro ubiquitination experiments show that VvPUB17 contains U-box and Armadillo repeats (ARM repeat) and has E3 ubiquitin ligase activity dependent on the conserved U-box motif. Transgenic plants showed elevated levels of key genes related to the SA defense response pathway and high concentrations of salicylic acid. CONCLUSIONS: VvPUB17 functions as an E3 ubiquitin ligase that enhances the resistance of grapes to powdery mildew through the SA signal pathway.