水稻水通道蛋白OsPIP维持水分内稳态和重金属镉解毒的机理研究

Cadmium pollution severely affected the quality and yield of rice, thereby affected national economy and human health in China. In our previous research, we have constructed the rice cDNA library, and screened this library with yeast heavy metal-sensitive mutant ycf1∆. OsPIP can complement the phenotype of this yeast mutant. OsPIPs belong to plant aquaporin family, and many studies showed that aquaporins were involved in stresses responsing and developmental processes of plants. It is supposed that OsPIPs can detoxify the ROS in yeast caused by heavy metal through transport the hydrogen peroxide; or regulate the water banlance in plant cell to perform the detoxification. In this project, we will adopt yeast and rice as experimental materials, apply multiple molecular biology approches, systematically explore the physiological and bilogical functions of OsPIPs responsing to heavy metal.(1) Detect the OsPIPs‘ compartmentalization in vacuolar under the cadmium stress by the means of GFP-fusion protein, and test the cadmium translocation in pant cells mediated by OsPIP trafficking; (2) By analyses of the water banlance-related genes' expression in rice, or detection of the yeast survival rate under dehydrofrozen challenge, investigate the correlation between cadmium detoxification and water balance; (3) The transgenic assay in rice will be performed to identify the biologial function of OsPIPs responding to heavy metal stresses, and clarify the mechanism of OsPIP affecting the Cd accumulation in rice. The research purpose of this project will will not only reveals the mechanisms of crop responding to cadmium stress in depth, but also provide a basis of relevance between cadmium stress and water balance. The results in this research can give some reference for problems of cadmium related food safety, and also be helpful for phytoremediation of heavy metal pollution.

镉污染严重地影响了水稻的品质和产量，进而影响农业经济和人类健康。水稻水通道蛋白OsPIP基因是我们通过筛选水稻cDNA的酵母表达文库获得的重金属镉解毒的候选功能基因。我们的初步研究表明，OsPIP1;1蛋白能够在酵母细胞中进行镉的解毒，并且重金属胁迫处理能够调控OsPIPs基因的表达，且首次证明部分OsPIPs蛋白成员可以转运过氧化氢。本项目将通过酵母和水稻两种实验体系，结合多种分子生物学研究方法，系统研究OsPIPs基因对细胞中镉的解毒以及对水稻中镉积累的影响。项目研究不仅有助于阐明水稻应对重金属镉的分子机理，也对镉积累和水平衡的相关性提供理论依据，研究成果也将为镉污染相关的粮食安全问题提供借鉴，也进一步对重金属污染的植物修复问题提供参考。

镉污染严重地影响了水稻的品质和产量，进而影响农业经济和人类健康。水稻水通道蛋白OsPIP1;1基因是我们通过筛选水稻cDNA的酵母表达文库获得的重金属镉解毒的候选功能基因。我们的初步研究表明，OsPIP1;1蛋白能够在酵母细胞中进行镉的解毒，并且重金属胁迫处理能够调控OsPIPs基因的表达，且首次证明部分OsPIPs蛋白成员可以转运过氧化氢。本项目通过酵母和水稻两种实验体系，结合多种分子生物学研究方法，系统研究OsPIPs基因对细胞中镉的解毒以及对水稻中镉积累的影响。(1) 酵母异源表达实验表明，OsPIP1;1蛋白能够转运Cd离子，但并不能转运H2O2，部分水稻OsPIP其他成员能够直接转运H2O2，证明OsPIP1;1蛋白对Cd离子的解毒与清除活性氧并没有直接的关系；(2) 水稻水通道蛋白基因的表达受Cd胁迫处理的调控；(3) OsPIP1;1基因在水稻中的下调表达能够降低水稻中的Cd含量。本项目研究结果表明水稻对重金属Cd的富集有水稻对水分的吸收有直接的关系，并从分子提供提供了证据；而部分水稻水通道蛋白基因可转运Cd离子，以及参与转运H2O2，进行重金属Cd胁迫导致的活性氧清除及氧化胁迫解毒。本项目对重要农作物的重金属富集的粮食安全问题提供借鉴。