Huang Xingchuan, Liu Yanan, Huang Jianhua, Fernando W G Dilantha, Li Xin, Xia Shitou
Hunan Provincial Key Laboratory of Phytohormones and Growth Development, College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China.
Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.
Front Plant Sci. 2022 May 25;13:881212. doi: 10.3389/fpls.2022.881212. eCollection 2022.
From a reverse genetic screen using CRISPR/Cas9 gene editing tool, we unintentionally identified an autoimmune mutant. Map-based cloning and whole-genome sequencing revealed that it contains a deletion in SMALL UBIQUITIN-RELATED MODIFIER (SUMO) protease encoding gene (). Previous studies reported that mutants accumulate elevated levels of plant defense hormone salicylic acid (SA). However, upregulated () expression in only partly relies on SA level. In this study, we show that plant metabolite N-hydroxypipecolic acid (NHP) biosynthetic genes are upregulated in , and NHP biosynthesis mutant () partially suppresses the autoimmune phenotypes of , suggestive of a requirement of NHP signaling for the autoimmunity in . As activation of nucleotide-binding leucine-rich repeat immune receptors (NLRs) are associates with the biosynthesis of SA and NHP and lipase-like protein ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) is a key component downstream of many NLRs, we examined the relationship between EDS1 and ESD4 by analyzing the double mutant. We found that largely suppresses autoimmunity and blocks the elevated expressions of SA and NHP biosynthesis-related genes in . Overall, our study provides evidence supporting the hypothesis that SUMO protease ESD4 likely targets a yet to be identified guardee of NLR by removing its SUMO modification to avoid recognition by the cognate NLR. Loss of ESD4 results in activation of NLR-mediated autoimmunity.
通过使用CRISPR/Cas9基因编辑工具进行反向遗传筛选，我们意外地鉴定出一个自身免疫突变体。基于图谱的克隆和全基因组测序表明，它在小泛素相关修饰物（SUMO）蛋白酶编码基因（）中存在一个缺失。先前的研究报道，突变体积累了高水平的植物防御激素水杨酸（SA）。然而，中上调的（）表达仅部分依赖于SA水平。在本研究中，我们表明植物代谢物N-羟基哌啶酸（NHP）生物合成基因在中上调，并且NHP生物合成突变体（）部分抑制了的自身免疫表型，这表明NHP信号传导对于中的自身免疫是必需的。由于核苷酸结合富含亮氨酸重复序列免疫受体（NLR）的激活与SA和NHP的生物合成相关，并且脂酶样蛋白增强疾病易感性1（EDS1）是许多NLR下游的关键组分，我们通过分析双突变体来研究EDS1和ESD4之间的关系。我们发现很大程度上抑制了的自身免疫，并阻断了中SA和NHP生物合成相关基因的上调表达。总体而言，我们的研究提供了证据支持以下假设：SUMO蛋白酶ESD4可能通过去除其SUMO修饰来靶向一个尚未确定的NLR的被守护者，以避免被同源NLR识别。ESD4的缺失导致NLR介导的自身免疫激活。
