植物大部分器官通过胚后发育形成，位于各类分生组织的干细胞是植物能够终生生长、持续发育形成新的器官和组织的基础。CLAVATA3(CLV3)/ESR-related(CLE)多肽信号在维持植物干细胞群动态平衡、器官发生和形态建成中起关键的调控作用。申请人以前的研究表明位于质膜上的LRR受体蛋白激酶CLV1/BAM1/BAM2以及CLV2-CORYNE形成两个受体复合体，分别接收CLE多肽信号。然而这些受体蛋白在接收CLE信号后引发胞内信号级联反应的方式尚不明确。本项目以拟南芥根端干细胞群为研究对象，综合应用遗传学及分子生物学手段，从受体蛋白亚细胞定位、自我磷酸化、受体复合体形成三个方面分析CLE多肽处理后BAM1/BAM2受体蛋白在分子和细胞水平的变化，以及这些变化对CLE信号传导的影响。本研究将阐明CLE多肽受体激活的分子机制，为进一步深入研究CLE途径胞内级联反应打基础。

Plants form most of their organs through post-embryogenetic development. As the source of continuously generated new organs, a population of stem cells are constantly maintained at various types of meristems throughout the lifespan of a plant. The CLAVATA3(CLV3)/ESR-related (CLE) peptide signals play a key role in the regulation of stem cell homeostasis, organogenesis and morphogenesis in plants. Previous studies by this applicant indicated that the plasma membrane-localized LRR-receptor-like kinases perceive CLE signals in the form of two receptor complexes, a CLV1/BAM1/BAM2 multimer and a CLV2-CORYNE multimer. How these receptor proteins initiate intracellular signal relay after ligand perception, however, is not clear. In this proposed study, using Arabidopsis root apical meristem as a model system, the mechanisms of receptor activation by CLE peptides will be investigated through 3 different aspects including subcellular localization, phosphorylation status of the receptor proteins and receptor complex formation. To this end, genetic, biochemical and cell biological approaches will be used to analyze changes of the Arabidopsis CLE receptor proteins BAM1 and BAM2 after CLE treatments. Effects of these changes on phenotypic read-outs will be determined to evaluate the significance of the CLE-induced changes on signal transduction. Results from this study will for the first time elucidate the molecular and cellular mechanisms of receptor activation by CLE peptide signals, which will facilitate further understanding of the intracellular signal relay initiated by CLE ligand binding.