小柯机器人

中国科学院分子植物科学卓越创新中心辛秀芳团队发现，NLR介导的植物免疫需要模式识别受体。该项研究成果于2021年3月10日在线发表在《自然》杂志上。

研究人员表示，植物免疫系统对于自然生态系统中的植物生存和农田的生产力至关重要。大量证据支持普遍的观点，即植物具有两级先天免疫系统，分别称为模式触发免疫（PTI）和效应触发免疫（ETI）。PTI由微生物模式通过细胞表面定位的模式识别受体（PRR）触发，而ETI由病原效应蛋白通过主要在细胞内定位的受体（称为核苷酸结合，富含亮氨酸的重复受体NLR）激活。PTI和ETI由不同的激活机制引发，并涉及不同的早期信号传导级联。

在这里，研究人员发现，拟南芥的PRR和PRR共受体突变体（fls2 efr cerk1和bak1 bkk1 cerk1三重突变体）在受到假单胞菌感染时，在ETI反应中受到了明显损害。研究人员进一步表明，NADPH氧化酶RBOHD产生活性氧是连接PRR和NLR介导免疫的关键早期信号事件，而受体样细胞质激酶BIK1对于RBOHD的完全激活、基因表达和ETI期间的细菌耐药性是必需的。此外，NLR信号迅速增加关键PTI组分的转录本和/或蛋白质水平。

这项研究支持修订后的模型，其中PTI的增强是细菌感染过程中ETI不可或缺的组成部分。这个模型从概念上将植物中的两个主要免疫信号级联统一，并从机制上解释了PTI和ETI之间下游防御输出中长期观察到的相似之处。

附：英文原文

Title: Pattern-recognition receptors are required for NLR-mediated plant immunity

Author: Minhang Yuan, Zeyu Jiang, Guozhi Bi, Kinya Nomura, Menghui Liu, Yiping Wang, Boying Cai, Jian-Min Zhou, Sheng Yang He, Xiu-Fang Xin

Issue&Volume: 2021-03-10

Abstract: The plant immune system is fundamental for plant survival in natural ecosystems and for productivity in crop fields. Substantial evidence supports the prevailing notion that plants possess a two-tiered innate immune system, called pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). PTI is triggered by microbial patterns via cell surface-localized pattern-recognition receptors (PRRs), whereas ETI is activated by pathogen effector proteins via predominantly intracellularly localized receptors called nucleotide-binding, leucine-rich repeat receptors (NLRs)1,2,3,4. PTI and ETI are initiated by distinct activation mechanisms and involve different early signalling cascades5,6. Here we show that Arabidopsis PRR and PRR co-receptor mutants—fls2 efr cerk1 and bak1 bkk1 cerk1 triple mutants—are markedly impaired in ETI responses when challenged with incompatible Pseudomonas syrinage bacteria. We further show that the production of reactive oxygen species by the NADPH oxidase RBOHD is a critical early signalling event connecting PRR- and NLR-mediated immunity, and that the receptor-like cytoplasmic kinase BIK1 is necessary for full activation of RBOHD, gene expression and bacterial resistance during ETI. Moreover, NLR signalling rapidly augments the transcript and/or protein levels of key PTI components. Our study supports a revised model in which potentiation of PTI is an indispensable component of ETI during bacterial infection. This revised model conceptually unites two major immune signalling cascades in plants and mechanistically explains some of the long-observed similarities in downstream defence outputs between PTI and ETI.

DOI: 10.1038/s41586-021-03316-6

Source: https://www.nature.com/articles/s41586-021-03316-6

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