番茄SGRL基因在叶绿素降解过程中的功能研究

Drought stress is one of the main factors that promote plant tissue senescence early following chlorophyll degradation as a main signal of senescence and cut down the production. STAY-GREEN LIKE (SGRL) is a principal regulator of senescence in green tissues of plant. ABA is an important signal regulator responding to drought stress which plays an essential role in senescence and chlorophyll degradation in plant tissues. As one of the important vegetable crops, tomato plays a crucial role in the vegetable industry in China. Its yield and quality are seriously affected by drought stress. It is ambiguous that the mechanism of SGRL in drought stress and the relationship between SGRL and ABA signaling pathway in tomato. In this research, we are planning to clone SGRL gene from tomato and to obtain sense and antisense transgenic tomato plants. It will be measured whether SGRL has the activity of Magnesium-Dechelatase. Yeast two-hybrid system will be used to screen the interaction proteins of SGRL, such as the chlorophyll degradation enzymes and photosynthesis related proteins. Yeast one-hybrid will be employed to find upstream regulatory factors of SGRL. The mechanism of chlorophyll degradation and role of SGRL protein in ABA signal pathway will be analyzed. These researches are great significance for high-yielding cultivation of vegetable crops.

干旱胁迫是促使植物组织提前衰老，进而减产的主要因素之一。叶绿素降解，则是植物组织衰老的主要征兆。滞绿蛋白STAY-GREEN LIKE（SGRL）是广泛存在于植物细胞内，影响绿色器官衰老的关键调控因子；ABA是响应干旱胁迫的重要信号分子，在植物组织衰老及叶绿素降解过程中起重要调控作用。番茄作为重要的蔬菜作物之一，在我国蔬菜产业中具有举足轻重的地位，其产量和品质受干旱胁迫影响严重。番茄中SGRL在干旱胁迫下的作用机制及SGRL与ABA信号通路的关系尚不明确。本项目拟克隆番茄SGRL蛋白基因，获得含SGRL正反义转基因植株；验证SGRL是否具有脱镁螯合酶活性；利用酵母双杂交等方法寻找与SGRL互作的叶绿素降解及光合作用相关蛋白；利用酵母单杂交分析SGRL上游ABA信号通路调控因子，探讨ABA在SGRL参与的叶绿素降解过程中的调控机制。该研究对于指导果实类蔬菜的高产栽培具有重要意义。

干旱胁迫是促使植物组织提前衰老，进而减产的主要因素之一。叶绿素降解，则是植物组织衰老的主要征兆。滞绿蛋白STAY-GREEN LIKE（SGRL）是广泛存在于植物细胞内，影响绿色器官衰老的关键调控因子；ABA是响应干旱胁迫的重要信号分子，在植物组织衰老及叶绿素降解过程中起重要调控作用。番茄作为重要的蔬菜作物之一，在我国蔬菜产业中具有举足轻重的地位，其产量和品质受干旱胁迫影响严重。番茄中SGRL在干旱胁迫下的作用机制及SGRL与ABA信号通路的关系尚不明确。本项目中我们克隆并获得番茄SGRL基因过表达株系。表达分析显示，SlSGRL受ABA诱导上调表达。ABA处理后，过表达株系与野生型相比，叶片出现早黄现象。通过酵母双杂交和双分子荧光互补实验发现SlSGRL可以与SlPPH和SlLHCa2相互作用，促进叶绿素降解；酵母单杂交、EMSA实验和LUC实验显示SlABI5和SlABI5-LIKE可以直接结合SlSGRL启动子上ABRE元件，促进其表达。