菌根共生过程中磷营养转运的调控机制研究

Most plant species including maize, rice and soybean, form endosymbioses with arbuscular mycorrhizal fungi that improve the uptake of water and mineral nutrients from the soil, in particular phosphate. In turn, host plant photosynthate is transferred to the mycorrhizal fungus. Previously we have revealed that MtHA1, encoding a proton ATPase energized the periarbuscular membrane, thereby facilitating phosphate uptake in arbusculated plant cells. However, the mechanism of regulating H+-ATPase activity in mycorrhizal symbiosis is still elusive. MtHIPs (HA1 Interaction Protein) were identified as MtHA1 interactors using yeast two hybridin my lab and HIP1 was specific induced by mycorrhizal infection. We will study the role of MtHIPs in regulating H+-ATPase activity and phosphate uptake during mycorrhizal symbiosis. Our new mycorrhizal defect mutant Mtiam1 (Impaired in Arbuscular Mycorrhizal Symbiosis 1) appears to function in the similar way to regulate phosphate uptake as MtHA1 in mycorrhizal symbiosis. This research will reveal how H+-ATPase activity is regulated in mycorrhizal symbiosis and provide important insights into the molecular mechanism of nutrient exchange in plant symbiosis.

80-90%陆生植物，包括玉米、水稻和大豆，可与丛枝菌根真菌形成共生。在共生中，植物传递碳源给菌根真菌供其生长；菌根真菌帮助植物高效吸收土壤中的磷氮等营养。申请人前期研究表明，定位于丛枝细胞膜上的质子泵MtHA1能驱动磷转运蛋白MtPT4从菌根真菌转运磷元素。但在菌根共生中质子泵活性调控的分子机制还不清楚。申请人通过文库筛选获得了MtHA1的互作蛋白MtHIPs（HA1 Interaction Protein），将深入研究MtHIPs对MtHA1活性的调节，揭示该复合体调控菌根共生的生理生化机制；同时通过遗传筛选获得了与Mtha1菌根共生表型类似突变体Mtiam1（Impaired in Arbuscular Mycorrhizal Symbiosis 1），通过克隆MtIAM1和功能分析，研究其对MtHA1质子泵活性和菌根共生的调控机理，阐明植物-菌根共生中以MtHA1为中心的调控网络。

80-90%植物，包括玉米、水稻和大豆，可与丛枝菌根真菌形成共生，帮助植物高效吸收土壤中的磷氮等营养，其中定位于丛枝细胞膜上的质子泵MtHA1能驱动磷转运蛋白MtPT4从菌根真菌转运磷元素本项目通过文库筛选获得了MtHA1的互作蛋白MtHIPs（HA1 Interaction Protein），发现MtHIP1与MtHA1在细胞膜互作。进一步研究发现MtHIP1受菌根共生诱导，其突变体及RNAi植物表现为丛枝结构发育受阻，磷营养交换受损，表明MtHIP1在菌根共生中的重要作用。本项目还获得了与Mtha1菌根共生表型类似突变体Mtiam1（Impaired in Arbuscular Mycorrhizal Symbiosis 1），研究发现MtIAM1基因受菌根共生诱导，并且MtHA1的表达在Mtiam1突变体不能正常诱导，说明MtIAM1可能通过MtHA1质子泵的基因表达，调控菌根共生。本项目为阐明植物-菌根共生中以MtHA1为中心的调控网络奠定了基础。