干旱是我国威胁粮食生产的重要非生物胁迫因素，认识和揭示植物感知和响应干旱胁迫的分子机理、克隆参与该生物过程的关键基因，是生物学研究的热点和难点。通过全基因组关联分析获得干旱候选基因：拟南芥接头蛋白复合物4的β亚基（AP-4β），受干旱与ABA诱导上调，其两个独立的T-DNA插入突变体，在中度干旱与重度干旱条件下都比野生型展现出更加耐旱的表型，离体叶片失水速率慢于野生型。在种子萌发阶段，突变体均呈现出对ABA的超敏感性，在ABA调控气孔运动实验中，突变体的气孔开度明显小于对照，暗示该基因可能负调控干旱应答反应。本项目拟揭示AP-4β通过调控蛋白转运来介导干旱应答反应的分子机制，不但有可能填补植物AP-4研究的空白，挖掘AP的新功能，而且还有可能开拓基于蛋白转运系统的非生物胁迫响应的新路径，为改善植物干旱耐受性提供新的候选基因。

Drought stress is a major environmental constrain which threatening food production. Revealing the molecular mechanism and cloning the key genes underlying plant sense and response to drought stress, are the research focus and difficulty of biologists. AP-4β, a drought-related candidate gene was acquired by genome-wide association studies (GWAS). It was induced by drought and ABA. Two independent T-DNA insertional ap-4β mutants displayed insensitive to drought stress under moderate and severed conditions, as well as slower water loss, compared to control. Furthermore, ap-4β mutants showed hypersensitive to ABA during ABA-regulated seed germination and stomata movement. These indicated that AP-4β maybe played roles in ABA-mediated drought response. On the other hand, AP-4β was a putative β-adptin subunit of adaptor protein 4 in Arabidopsis. Adaptor protein mainly participated in protein transport in mammal, yeast and plant. However, the relationship between adaptor protein and abiotic stress have largely unknown to date. We will use diversed methods such as cell biology, biochemistry and molecular biology technology to elucidate the molecular mechanism underlying drought response by the way of AP-4β-regulated protein transport system. This study not only can fill the gaps in research AP-4 in plant, unearth new function of adaptor protein, but also can expand the knowledge about abiotic stress response basis on protein transport system and supply new candidates for improved drought tolerance.