GLYI-4 functions downstream of NAC72 to modulate downy mildew resistance in grapevine
Tiemei Li, Xin Cheng, Xiaowei Wang, Guanggui Li, Bianbian Wang, Wenyuan Wang, Na Zhang, Yulei Han, Bolei Jiao, Yuejin Wang, Guotian Liu, Tengfei Xu, Yan Xu
The Plant Journal
DOI: 10.1111/tpj.15447
Abstract
Glyoxalase I (GLYI) is part of the glyoxalase system and its the major function is the detoxification of α-ketoaldehydes, including the potent and cytotoxic methylglyoxal (MG). MG disrupts mitochondrial respiration and increases production of reactive oxygen species, which increased during pathogen infection of plant tissues, but few studies relating the glyoxalase system on plant pathogen response. We used the promoter of the VvGLYI-4 to screen the upstream transcription factors and reported a NAC (NAM/ATAF/CUC) domain-containing transcription factor VvNAC72 in grapevine, which was localized to the nucleus. Our results showed that VvNAC72 expression was induced by downy mildew Plasmopara viticola, whereas the transcript level of VvGLYI-4 decreased. Following analysis revealed that VvNAC72 can directly bind to the promoter region of VvGLYI-4 via CACGTG element, leading to the inhibition of VvGLYI-4 transcription. Further stable overexpression of VvNAC72 in grapevine and tobacco showed decreased expression level of VvGLYI-4, increased contents of MG and ROS, as well as stronger resistance to pathogen stress. Taken together, these results demonstrate that grapevine VvNAC72 negatively modulates MG detoxification through repression of VvGLYI-4, and finally enhances resistance to downy mildew, at least in part, via the modulation of MG-associated ROS homeostasis through salicylic acid (SA)-mediated defense pathway.