Functional Characterization of Resistance to Powdery Mildew of VvTIFY9 from Vitis vinifera

Powdery mildew is a disease caused by fungal pathogens that harms grape leaves and fruits. The TIFY gene family is a plant-specific super-family involved in the process of plants' development and their biotic and abiotic stress responses. This study aimed to learn the function of the VvTIFY9 gene to investigate molecular mechanisms of grape resistance to powdery mildew. A VvTIFY9 protein encoding a conserved motif (TIF[F/Y]XG) was characterized in grape (Vitis vinifera). Sequence analysis confirmed that VvTIFY9 contained this conserved motif (TIF[F/Y]XG). Quantitative PCR analysis of VvTIFY9 in various grape tissues demonstrated that the expression of VvTIFY9 was higher in grape leaves. VvTIFY9 was induced by salicylic acid (SA) and methyl jasmonate (MeJA) and it also quickly responded to infection with Erysiphe necator in grape. Analysis of the subcellular localization and transcriptional activation activity of VvTIFY9 showed that VvTIFY9 located to the nucleus and had transcriptional activity. Arabidopsis that overexpressed VvTIFY9 were more resistant to Golovinomyces cichoracearum, and quantitative PCR revealed that two defense-related genes, AtPR1 and AtPDF1.2, were up-regulated in the overexpressing lines. These results indicate that VvTIFY9 is intimately involved in SA-mediated resistance to grape powdery mildew. This study provides the basis for exploring the molecular mechanism of grape resistance to disease resistance and candidate genes for transgenic disease resistance breeding of grape plants.