The susceptibility factor RTP1 negatively regulates Arabidopsis immunity by interacting with the cytochrome P450 protein CYP71B3.
Wei, Yushu; Zong, Deqian; Tang, Yaling; Kong, Lehui; Gao, Xianxian; Wang, Xiaoxue; Zhang, Yingqi; Yang, Yang; Qiang, Xiaoyu; Shan, Weixing
Plant physiology
DOI：10.1093/plphys/kiaf284
Abstract
Oomycetes, particularly Phytophthora species, cause destructive plant diseases that severely threaten sustainable crop production. Due to the loss of genotype-specific disease resistance, it is important to identify and understand immune factors that mediate plant susceptibility. Loss-of-function of the susceptibility factor Resistance To Phytophthora parasitica 1 (RTP1) leads to broad-spectrum disease resistance in Arabidopsis thaliana(Arabidopsis thaliana (L.) Heynh.). Through RNA-seq analysis, we determined that CYP71B3, encoding an uncharacterized P450 enzyme, is significantly up-regulated in rtp1 mutant plants infected with P. parasitica. Loss-of-function of CYP71B3 led to abolished pathogen-associated molecular pattern (PAMP)-triggered oxidative burst and rendered Arabidopsis more susceptible to diverse pathogens, including the oomycete P. parasitica and bacterial Pseudomonas syringae. Conversely, overexpression of CYP71B3 enhanced plant resistance and PAMP-triggered oxidative burst. CYP71B3 localized in the endoplasmic reticulum and was destabilized by interacting with RTP1 via the I-38 residue, which is essential for its immune function and P450 enzyme activity. The expression of CYP71B3 was regulated by transcription factor bZIP60, which is required for rtp1-mediated resistance to P. parasitica. Our studies indicate that RTP1 mediates plant susceptibility by destabilizing the downstream positive immune factor CYP71B3.