A LysM Receptor-like Kinase Mediates Chitin Perception and Fungal Resistance in Arabidopsis. Arabidopsis thaliana

A LysM Receptor-like Kinase Mediates Chitin Perception and Fungal Resistance in Arabidopsis Jinrong Wan,1 Xuecheng Zhang,1 David Neece,2 Katrina M. Ramonell,3 Steve Clough,2,4 Sung-yong Kim,1 Minviluz Stacey,1 and Gary Stacey1* 1Division of Plant Sciences, National Center for Soybean Biotechnology, C.S. Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA 2Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA 3Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA 4US Department of Agriculture, Soybean/Maize Germplasm, Pathology and Genetics Research, Urbana, IL 61801, USA *To whom correspondence should be addressed. E-mail: [e-mail] Abstract: Chitin, a polymer of N-acetyl-D-glucosamine, is found in fungal cell walls, but not in plants. Plant cells are capable of perceiving chitin fragments (chitooligosaccharides) to trigger various defense responses. We identified a LysM receptor-like protein (AtLysM RLK1) that is required for the perception of chitooligosaccharides in Arabidopsis. Mutation of this gene blocked the induction of almost all chitooligosaccharide-responsive genes (CRGs) and led to more susceptibility to fungal pathogens, but not to a bacterial pathogen. In addition, exogenously applied chitooligosaccharides enhanced resistance against both fungal and bacterial pathogens in the wild-type plants, but not in the mutant. Together, our data strongly suggest AtLysM RLK1 is the chitin receptor or a key part of the receptor complex and chitin is a PAMP (pathogen-associated molecular pattern) in fungi recognized by the receptor leading to the induction of plant innate immunity against fungal pathogens. Since LysM RLKs were also recently shown to be critical for the perception of the rhizobial lipo-chitin Nod signals, our data suggest that LysM RLKs not just recognize friendly symbiotic rhizobia (via their lipo-chitin Nod signals), but also hostile fungal pathogens (via their cell wall chitin). These data suggest a possible evolutionary relationship between the perception mechanisms of Nod signals and chitin by plants. Keywords: chitooctaose, chitin receptor mutant Overall design: wild type Col-0 and chitin receptor mutants treated with or without chitooctaose

拟南芥中一种LysM受体样激酶（LysM Receptor-like Kinase）介导几丁质感知与真菌抗性

作者：万锦荣¹, 张学成¹, David Neece², Katrina M. Ramonell³, Steve Clough²,⁴, 金成勇¹, Minviluz Stacey¹, 及Gary Stacey¹*

¹美国密苏里大学哥伦比亚分校植物科学系、国家大豆生物技术中心、C.S.邦德生命科学中心，哥伦比亚，MO 65211
²美国伊利诺伊大学厄巴纳-香槟分校作物科学系，厄巴纳，IL 61801
³美国阿拉巴马大学生物科学系，塔斯卡卢萨，AL 35487
⁴美国农业部大豆/玉米种质、病理学与遗传学研究室，厄巴纳，IL 61801

*通讯作者。电子邮箱：[e-mail]

摘要：几丁质（chitin）是N-乙酰-D-葡糖胺的聚合物，存在于真菌细胞壁中，而植物体内不含该物质。植物细胞可感知几丁质片段（几丁寡糖，chitooligosaccharides），进而触发多种防御反应。本研究在拟南芥中鉴定出一种参与几丁寡糖感知的LysM受体样蛋白（AtLysM RLK1）。该基因突变后，几乎所有几丁寡糖响应基因（CRGs）的诱导过程均被阻断，且植株对真菌病原体的敏感性升高，但对细菌病原体无显著影响。此外，外源施加几丁寡糖可增强野生型植株对真菌和细菌病原体的抗性，但该效应在突变体中并未显现。综上，本研究数据强烈表明AtLysM RLK1是几丁质受体或受体复合物的关键组分；几丁质作为真菌的病原相关分子模式（PAMP，pathogen-associated molecular pattern），可被该受体识别，进而诱导植物针对真菌病原体的先天免疫。此前已有研究证实，LysM受体样激酶（LysM RLKs）对于根瘤菌脂几丁质Nod信号的感知至关重要，本研究结果提示，LysM受体样激酶不仅可通过脂几丁质Nod信号识别友好的共生根瘤菌，还可通过真菌细胞壁中的几丁质识别敌对的真菌病原体。上述结果表明，植物对Nod信号与几丁质的感知机制可能存在进化关联。

关键词：八聚几丁糖（chitooctaose）、几丁质受体突变体

总体实验设计：采用八聚几丁糖处理与未处理的野生型Col-0及几丁质受体突变体