Signaling Mechanisms in Plant Innate Immunity

描述（由申请人提供）：先天免疫系统是针对感染性疾病的第一道诱导性防御。先天免疫的一个关键功能是检测病原体相关的分子模式（PAMP），而不是宿主细胞产生的感染因子和适当的防御反应的启动。最近的研究发现，PAMPs在富含亮氨酸重复序列（LRR）受体的识别以及植物、昆虫、蠕虫和哺乳动物先天免疫应答的信号传导机制中具有显着的保守性。我们建议使用整合的分子，细胞，生物化学，基因组和遗传学的方法来阐明一个定义明确的细菌鞭毛蛋白肽激发子flg 22在模式植物拟南芥诱导的信号转导途径。该研究计划将重点研究MAPKKK（MEKK 1）和小GT3（ROP 11），它们与flg 22受体激酶（FLS 2）相互作用，分别介导MAPK依赖性和MAPK非依赖性途径，并在flg 22信号传导中会聚于WRKY 22/29转录因子。将使用原生质体瞬时测定和转基因及突变体植物进行研究。四个具体目标是：1）研究将特异性MAPK级联与flg 22受体FLS 2连接的分子机制（一种LRR受体激酶）2）阐明ROP 11-FLS 2相互作用在flg 22信号传导中的功能和机制3）确定flg 22信号传导中WRKY 22/29转录因子的直接靶基因4）确定flg 22 MAPK级联、ROP 11、和WRKY 22/29在使用转基因和突变体植物对抗细菌和真菌病原体的植物防御反应中的作用。鞭毛蛋白肽flg 22和许多其他病原体衍生的激发子诱导保守的信号传导反应，如蛋白激酶激活、钙内流、氧化信号传导和转录重编程。对flg 22 MAPK级联、ROP 11和WRKY 22/29转录因子的研究将增强我们对先天免疫反应早期事件的分子机制的理解，并提高我们操纵植物持久抗病性的能力。

DESCRIPTION (provided by applicant): The innate immune system is the first line of inducible defense against infectious disease. A key function of innate immunity is the detection of pathogen-associated molecular patterns (PAMPs) produced by infectious agents but not host cells and the launch of appropriate defense responses. Recent discoveries have revealed remarkable conservation in the recognition of PAMPs by leucine-rich-repeat (LRR) receptors and in signaling mechanisms of innate immune responses in plants, insects, worms, and mammals. We propose to use integrative molecular, cellular, biochemical, genomic, and genetic approaches to elucidate the signal transduction pathways induced by a well-defined bacterial flagellin peptide elicitor flg22 in the model plant Arabidopsis thaliana. The Research proposal will focus on the investigation of a MAPKKK (MEKK1) and a small GTPase (ROP11), that interact with the flg22 receptor kinase (FLS2) and mediate MAPK-dependent and MAPK-independent pathways, respectively, and converge on WRKY22/29 transcription factors in flg22 signaling. Protoplast transient assays and transgenic and mutant plants will be used for the studies. Four specific aims are: 1) Investigate the molecular mechanisms that link a specific MAPK cascade to the flg22 receptor FLS2 (a LRR receptor kinase) 2) Elucidate the function and mechanisms of ROP11-FLS2 interaction in flg22 signaling 3) Define the direct target genes of WRKY22/29 transcription factors in flg22 signaling 4) Determine the roles of the flg22 MAPK cascade, ROP11, and WRKY22/29 in plant defense responses against bacterial and fungal pathogens using transgenic and mutant plants. It has been well documented that flagellin peptide flg22 and many other pathogen-derived elicitors induce conserved signaling responses such as protein kinase activation, calcium influx, oxidative signaling, and transcriptional reprogramming. The proposed studies on the flg22 MAPK cascade, ROP11, and WRKY22/29 transcription factors that act downstream of FLS2 receptor kinase in early flg22 signaling will enhance our understanding of the molecular mechanisms underlying the early events of innate immune responses and improve our ability to manipulate durable disease resistance in plants.