DELLA家族在花生干旱/高盐胁迫响应中的功能研究

Drought and salinization is the common factor affecting grown of plant and resulting in reduction in crop yield worldwide. Recent advances revealed the role of DELLAs in many aspects of plant growth that are influenced by environmental cues, such as excess salt, drought, or cold. It was proposed that DELLAs integrate environmental signals that enable plants to adapt their growth and development according to their surrounding environment, thus promote survival in an adverse environment. In our earlier studies, we cloned four AhDELLA homologue genes from peanut, molecular phylogenetic analysis revealed that these four AhDELLAs fall into three distinct groups: AhDELLA1 and AhDELLA2 clustered into two distinct groups, while AhDELLA3 and AhDELLA4 were in one group, which was separated from other DELLAs. Q-PCR results showed that the mRNA transcript of AhDELLA3 and AhDELLA4 in peanut rapidly induced under drought and high salinity stresses, which was different with in Arabidopsis. In this study, we plan to analyze the expression profile and their promoter activites of AhDELLA family response to drought and high salinity stresses. Then screen the interaction proteins by protein-protein interaction and the transcription factors of the promoters by yeast one hybrid system. Construct the overexpression plants and analyze the effects of AhDELLA gene on the gene expression and stress resistance of transgene plants. These results may provide valuable information for us to understand the function of DELLA family in the salt/drought stress responses in peanut.

干旱和盐渍化是影响植物生长发育，导致农作物减产的普遍因素。植物在受到高盐、干旱、冷等逆境胁迫时，DELLA通过整合环境信号对其生长发育状况做出适当的调整，从而增强植物对环境的适应能力。我们在前期工作中从花生克隆到4个DELLA基因，命名为AhDELLA1~AhDELLA4。系统进化树分析表明AhDELLA3和AhDELLA4与其他DELLA亲缘关系较远，处于单独的一支，可能具有不同的作用。荧光定量PCR分析表明花生AhDELLA3和AhDELLA4基因在干旱和高盐胁迫下表达量显著升高，与拟南芥有一定的差异。本项目拟分析花生DELLA家族基因表达调控模式和启动子元件，鉴定DELLA蛋白的互作因子及与其启动子结合的转录调控因子，利用转基因植物材料研究DELLA对植物抗逆性的影响及转基因植物中其他抗逆相关基因的表达变化，从而探讨DELLA家族在调控花生干旱和高盐胁迫响应中的作用。

DELLA蛋白是赤霉素信号途径的关键抑制因子，近年来研究发现DELLA在植物抵抗逆境胁迫过程中也发挥了重要的作用。本项目中，我们从花生中克隆到4个DELLA基因，Q-PCR分析表明花生AhDELLA3a和AhDELLA3b基因在干旱和高盐胁迫下表达量显著升高。克隆了AhDELLA1、AhDELLA2、AhDELLA3a的启动子转化烟草，GUS染色表明AhDELLA3a基因的启动子具有干旱和高盐诱导活性，并进一步对AhDELLA3a启动子进行了分区研究。利用转基因烟草证明花生AhDELLA家族基因均能提高烟草对干旱和高盐的胁迫抗性，具体表现为在干旱和高盐胁迫处理下，AhDELLA转基因烟草的长势均比野生型烟草好，AhDELLA转基因烟草中的SOD、POD酶活性比野生型烟草中升高更显著。证明了AhDELLA1与AhGID1蛋白在GA存在下互作，并筛选到218个候选互作蛋白。本研究对阐明AhDELLA家族基因在花生抵抗逆境胁迫中的分子机理具有重要意义，为培育高抗逆的花生新种奠定理论基础。