自噬是一种在真核生物中高度保守的细胞代谢过程。受损的蛋白质或细胞器被包裹在双层膜的自噬体后运到液泡/溶酶体降解。我们前期使用3D电子断层扫描技术成功阐释植物自噬体起源于内质网的机制，但自噬体-液泡融合机制尚不清楚。我们已报道Rab7蛋白在被MON1-CCZ1复合体激活之后参与调控多囊泡体到液泡的运输，而Rab7定位于液泡膜上，提示Rab7可能调控植物自噬体与液泡的融合。近期预实验结果显示，在自噬诱导药物处理后，Rab7蛋白同时定位于自噬体和液泡。此外，诱导自噬下的mon1突变体（Rab7处于非激活状态）的细胞质中聚集了大量的异常多层膜自噬体结构，提示Rab7或MON1-CCZ1复合体功能缺失阻碍自噬。本项目将在前期研究基础上，采用细胞分子生物学、生物化学和遗传学等方法并结合前沿的3D电子断层扫描技术，深入探讨植物自噬体-液泡融合的分子机制，为改良农作物抗逆能力提供新靶点新思路。

Autophagy is a highly conserved metabolic process in eukaryotic cells that executed by double-membrane autophagosomes to degrade and recycle aggregated proteins and damaged organelles which eventually fuse with vacuoles (in yeast and plants) or lysosomes (in animals). We have demonstrated that the autophagosome originates from the endoplasmic reticulum (ER) in plants using 3D electron tomography (ET) albeit the mechanism underlying autophagosome-vacuole fusion is still unclear. Lately, we have found that Rab7, which mediates transport from multivesicular bodies (MVBs) to the vacuole after its activation by the MON1-CCZ1 complex, localizes on the tonoplast, indicating its potential role in autophagosome-vacuole fusion. Our recent preliminary results showed that Rab7 localized on the vacuole membrane as well as the autophagosome membrane under autophagy induction. Moreover, there were abundant enlarged abnormal multilayer autophagosomes accumulating in the cytosol of autophagy-induced mon1 mutant (in which Rab7 was inactivated). These findings suggested that dysfunction of Rab7 or MON1-CCZ1 complex would impede autophagy especially fusion between the autophagosome and the vacuole in plants. Therefore, based on our previous study, we will take biological, biochemical and genetic approaches along with 3D ET to study the molecular mechanism of autophagosome-vacuole fusion in plants in the hope of offering new targets and insights for improving crop stress resistance.