Signaling Mechanisms in Plant Innate Immunity

描述（由申请人提供）：先天免疫系统是抵御传染病的第一道诱导防线。先天免疫的一个关键功能是检测由感染因子而不是宿主细胞产生的病原体相关分子模式（PAMPs），并启动适当的防御反应。最近的研究发现，在植物、昆虫、蠕虫和哺乳动物中，亮氨酸富重复（LRR）受体对PAMPs的识别以及先天免疫反应的信号机制中，PAMPs具有显著的保守性。我们建议使用综合分子、细胞、生化、基因组和遗传学方法来阐明由定义明确的细菌鞭毛蛋白肽激发子flg22在模式植物拟南芥中诱导的信号转导途径。该研究计划将重点研究MAPKKK （MEKK1）和小GTPase (ROP11)，它们分别与flg22受体激酶（FLS2）相互作用，介导mapk依赖和mapk独立通路，并在flg22信号传导中汇聚WRKY22/29转录因子。原生质体瞬态试验、转基因和突变植物将用于研究。四个具体目标是：1)研究特异性MAPK级联与flg22受体FLS2（一种LRR受体激酶）的分子机制；2)阐明ROP11-FLS2相互作用在flg22信号传导中的功能和机制；3)确定WRKY22/29转录因子在flg22信号传导中的直接靶基因；4)利用转基因和突变植物确定flg22 MAPK级联、ROP11和WRKY22/29在植物对细菌和真菌病原体的防御反应中的作用。鞭毛蛋白肽flg22和许多其他病原体衍生的激发子诱导保守的信号反应，如蛋白激酶激活、钙内流、氧化信号和转录重编程。对flg22 MAPK级联、ROP11和WRKY22/29转录因子在flg22早期信号传导中作用于FLS2受体激酶下游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.