水稻-菌根真菌共生信号的系统解析

80-90%的陆生植物都可以与菌根真菌形成共生，其中豆科植物既能形成菌根共生又能形成根瘤固氮共生。菌根共生和根瘤共生的建立依赖于植物对菌根因子和结瘤因子的识别，其中豆科植物识别结瘤因子的两个受体已被克隆，但是植物识别菌根因子的受体还没有被证实，其信号转导的分子机制也不清楚。本项目前期的工作初步表明OsMYR1直接结合菌根因子，并与OsCERK1形成菌根因子受体复合体，申请人将以它们为诱饵蛋白，分离和鉴定菌根因子受体蛋白复合物的新组分，揭示植物识别菌根因子的生化机制；通过研究菌根共生相关的细胞质类受体激酶RLCKs和UBPs与OsCERK1互作及传递信号的分子机理，建立植物识别菌根因子信号转导途径；通过对菌根信号转导中不依赖于钙离子激活途径的关键核膜蛋白AAM1的功能研究，深入阐明植物-丛枝菌根真菌信号识别的分子机制及调控网络，为在水稻中建立共生固氮体系打下基础。

Plants establish symbiotic relationships with mycorrhizal fungi or rhizobial bacteria to help plants capture nutrients from environment and maintain their growth and development. Colonisation by these microorganisms requires plant recognition of diffusible signaling molecules, such as mycorrhizal (Myc) factors secreted from mycorrhizal fungi or Nod factors secreted from rhizobia. Two Nod factors receptors have been defined, but the Myc factors receptors are still missing, although several LysM domain proteins have been suggested to be involved in arbuscular mycorrhizal symbiosis. Our primary data indicated that OsCERK1 and OsMYR1 proteins are two key components of the Myc factors receptor complex. We will use these two proteins as baits to screen and identify other components of Myc factors receptor complex. We have identified two other OsCERK1 interactors, OsRLCKs and OsUBPs which are necessary for mycorrhizal symbiosis. This research will provide important insights into how OsCERK1-OsMYR1-mediated Myc factor perception actives calcium oscillations in nucleus. In addition, our ongoing project appears to reveal a new signaling pathway controlled by Abolished Arbuscule Mycorrhizal Symbiosis (AAM1) gene, which is independent on common signaling pathway. Based on our knowledge of perception of mycorrhizal fungi by plant, we will try to engineer Nod factor perception in non-legume rice. Our immediate aim is to achieve a comprehensive understanding of the mycorrhizal signaling and infection. This will provide a foundation for improvements in mycorrhization of crop species. Our long-term aim is to create the knowledge and infrastructure to allow the engineering of a nitrogen-fixing symbiosis in cereals.