水稻中一个ABA 8′-羟化酶基因OsABA8ox2对水稻水分平衡和生长发育的影响及机制研究

It is an important research subject that how ABA metabolism and its signaling are responsive to both developmental and environmental cues and incorporate environmental information into its developmental program to adapt to the environment. Compared with ABA synthesis and signaling pathways, the contribution of ABA catabolism in plant developmental process and the adaptation to the unfavorable environment was rarely demonstrated, especially in rice. ABA 8′-hydroxylase is known as the key enzyme of ABA catabolism. OsABA8ox2 encodes ABA 8′-hydroxylase in rice. Previous work of this project is based on the wilting phenotype of OsABA8ox2-overexpressing rice. We primarily demonstrated that OsABA8ox2 overexpression enhances stomatal opening, greatly reduces the water retention capacity of rice seedling, and leads to a very great difficulty in rice survival. Meanwhile, OsABA8ox2 overexpression has substantial effects on the development of root and panicle, and leads to a very low seed-set rate, even sterility. In this project, OsABA8ox2 overexpression and RNAi transgenic rice will be used as the plant materials. Their phenotypes will be observed. The specific spatio-temporal expression patterns and subcellular localization of three OsABA8ox genes will be investigated. ABA signal intensity and content will be measured, which can be accompanied by the observation of transverse sections of root and anther. The physiological indexes related to stomatal status will be measured. Furthermore, we will perform the analysis and comparison of the transcriptomes of WT, OsABA8ox2 overexpression and RNAi transgenic rice under normal and water stress conditions. This project aims to investigate the effects of upregulation/downregulation of OsABA8ox2 on water balance, growth and development in rice and the underlying mechanism, reveal the specificity of cell/tissue and development stage of OsABA8ox2 modulation in ABA catabolism. This study will shed new light on the molecular mechanism of the integration of developmental and environmental signals (such as water stress) by ABA in plant, and the theoretical basis for the better development of transgenic rice suitable to sustain optimal growth even when exposed to water stress environment.

植物如何通过ABA响应发育和环境信号，将环境信息并入其发育程序来适应环境，是一个重大研究课题。相比ABA合成和信号途径，对ABA分解途径的贡献阐释较少。本项目前期工作主要是基于ABA分解途径中一个关键酶（ABA 8′-羟化酶）基因OsABA8ox2过表达水稻株系出现的萎蔫表型展开，探明OsABA8ox2过表达加强气孔开放，大大降低水稻水分保持能力，因此很难存活；同时严重影响根、穗发育，结实率极低。本项目拟以OsABA8ox2 过表达和RNAi转基因株系为材料，进行OsABA8ox时空表达模式和亚细胞定位分析，ABA信号强度和含量检测，根、花药横切观察，气孔状态相关生理指标检测，正常和水胁迫条件下转录组分析，解析OsABA8ox2对水稻水分平衡和生长发育的影响及机制，探索OsABA8ox2调控ABA分解途径的细胞/组织和发育时期特异性。该研究将为ABA整合发育和环境信号的机制提供新见解。