脱落酸ABA是植物调控生长发育和响应逆境胁迫的一种关键激素。作为该信号通路中重要的一环，ABA受体的稳定性受到泛素蛋白酶体系统和内吞作用的调控。但能否被细胞内的主要降解途径－细胞自噬调控仍有待研究。我们前期研究发现细胞自噬对ABA受体具有上位效应并介导了它们的自噬降解；进而还发现ABA受体PYL4/7可通过一个ATG8互作蛋白AIP1的介导被液泡降解。由此，我们首次提出ABA受体降解的新机制：通过AIP1的介导，细胞可以选择性自噬降解部分的ABA受体，从而调控该信号通路。本项目拟以生化、细胞生物学和遗传学的方法解析AIP1的功能，从而阐述ABA受体选择性自噬降解的分子机制，还将探讨细胞自噬与内吞作用在调控ABA受体稳定性方面的相互关系。本研究不仅可为深入理解ABA信号通路的调控作出贡献，还能为更好地理解植物自噬对逆境胁迫的响应机制，为植物抗逆性研究及作物改良提供理论参照。

The phytohormone abscisic acid (ABA) plays vital roles in plant development and in abiotic stress responses. Many studies have shown that ABA signaling is regulated at the transcriptional, translational and post-translational levels. Recently, increasing evidence demonstrates that ABA receptors are degraded not only through the ubiquitin-26S proteasome system but also through the endocytic trafficking pathway. However, it is still largely unknown whether ABA receptor can be turnover by autophagy, one of the major intracellular catabolic pathways. Our prior work has found that Arabidopsis autophagy mutants are sensitive to ABA during germination and have better tolerance to drought stress. Further genetic relationship analysis revealed that the key autophagy components, ATG5 and ATG7, likely act epistatically upstream of ABA receptors. In addition, we found that these receptors could be selectively degraded by autophagy mediated by an ATG8 interacting Protein 1 (AIP1). The objectives of this proposal are to (i) further define the impact of autophagy deficiency on ABA signaling transduction; (ii) reveal the mechanism of selective autophagic degradation of ABA receptors mediated by AIP1 protein; (iii) study the relationship between autophagy and endocytosis on the vacuolar degradation of ABA receptors. Collectively, these experiments will help us better understand the role of autophagy in abiotic stress responses in plant, and may also provide us clues for improving crop abiotic stress resistance.