Ammonium stress increases microautophagic activity while impairing macroautophagic flux in Arabidopsis roots
Ammonium stress increases microautophagic activity while impairing macroautophagic flux in Arabidopsis roots
复制标题
铵胁迫增加拟南芥根部的微自噬活性，同时损害巨自噬通量
DOI：
10.1111/tpj.15091
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
K.
中科院分区：
文献类型：
--
作者：
Robert;G.;Yagyu;M.;Koizumi;T.;Naya;L.;Masclaux-Daubresse;C.;and Yoshimoto;K.
植物对NH 4+胁迫的反应是复杂的，植物对NH 4+的敏感性和耐受性可能涉及多种机制。在这里，我们证明了在NH 4+毒性条件下生长的植物中，宏观和微观自噬活性受到相反的影响。当生长在NH 4+胁迫条件下，macroautophagic活动受损的根。根细胞在细胞质中积累自噬体，但表现出较少的自噬通量，表明在NH 4+胁迫条件下，大自噬过程的后期步骤受到影响。在这种情况下，我们还发现CCZ 1-MON 1复合物是液泡传递途径的关键因子，在拟南芥中的大自噬途径的后期发挥作用。相反，在NH 4+胁迫植物根细胞的液泡腔中观察到液泡膜衍生的小泡的积累，表明诱导了微自噬样过程。在这个意义上，一些SYP 22-，但主要是VAMP 711-阳性囊泡内观察到的NH 4+胁迫植物的根液泡。与液泡膜降解增加和由于宏观自噬通量受损而导致的液泡膜流量减少一致，NH 4+胁迫植物根细胞的液泡显示出简化的结构和较低的液泡膜含量。两者合计，这项研究提出的证据，假设后期步骤的macroautophagic过程作为相关的生理机制的NH 4+敏感性反应在拟南芥，并提供了深入了解的分子工具，研究植物中的microautophagy。
Plant responses to NH4+stress are complex, and multiple mechanisms underlying NH4+sensitivity and tolerance in plants may be involved. Here, we demonstrate that macro‐ and microautophagic activities are oppositely affected in plants grown under NH4+toxicity conditions. When grown under NH4+stress conditions, macroautophagic activity was impaired in roots. Root cells accumulated autophagosomes in the cytoplasm, but showed less autophagic flux, indicating that late steps of the macroautophagy process are affected under NH4+stress conditions. Under this scenario, we also found that the CCZ1‐MON1 complex, a critical factor for vacuole delivery pathways, functions in the late step of the macroautophagic pathway in Arabidopsis. In contrast, an accumulation of tonoplast‐derived vesicles was observed in vacuolar lumens of root cells of NH4+‐stressed plants, suggesting the induction of a microautophagy‐like process. In this sense, some SYP22‐, but mainly VAMP711‐positive vesicles were observed inside vacuole in roots of NH4+‐stressed plants. Consistent with the increased tonoplast degradation and the reduced membrane flow to the vacuole due to the impaired macroautophagic flux, the vacuoles of root cells of NH4+‐stressed plants showed a simplified structure and lower tonoplast content. Taken together, this study presents evidence that postulates late steps of the macroautophagic process as a relevant physiological mechanism underlying the NH4+sensitivity response in Arabidopsis, and additionally provides insights into the molecular tools for studying microautophagy in plants.