Department of Life Science, School of Agriculture, Meiji University, Tama-ku, Kawasaki, Kanagawa, Japan.
Life Sciences Program, Graduate School of Agriculture, Meiji University, Tama-ku, Kawasaki, Kanagawa, Japan.
Plant Signal Behav. 2020 May 3;15(5):1746042. doi: 10.1080/15592324.2020.1746042. Epub 2020 Mar 31.
Autophagy, which is one of the self-degradation systems, promotes intracellular zinc (Zn) recycling under Zn deficiency (-Zn) in plants. Therefore, autophagy defective plants show severe chlorosis under -Zn. Root is the plant organ which directly exposed to Zn deficient environment, however, in our recent study, -Zn symptom was prominently observed in leaves as chlorosis. Here, we conducted micrografting to determine which organ's autophagic activities are important to suppress the -Zn induced chlorosis. Grafted plants that have autophagic activities only in roots or leaves were grown under -Zn and then compared chlorotic phenotypes among them. As a result, regardless of the autophagic activities in rootstocks, -Zn induced-chlorosis in leaves was occurred only when autophagy in scion was defective. This data indicates that Zn resupplied by autophagic degradation in root cells could not contribute to suppress the chlorosis in leaves. Thus, autophagy in the aerial part is critical for controlling -Zn induced-chlorosis in leaves. Taken together, along with our recently reported data, we conclude that the mechanism of Zn resupply by autophagic degradation is not systemic throughout the plant but rather a local system.
自噬是一种自我降解系统，它在植物缺锌（-Zn）时促进细胞内锌（Zn）的再循环。因此，自噬缺陷的植物在 -Zn 下表现出严重的黄化。根是直接暴露在缺锌环境中的植物器官，但在我们最近的研究中，-Zn 症状明显表现在叶片黄化上。在这里，我们进行了微嫁接实验来确定哪个器官的自噬活性对抑制 -Zn 诱导的黄化是重要的。在 -Zn 条件下生长仅在根或叶中具有自噬活性的嫁接植物，然后比较它们之间的黄化表型。结果表明，无论砧木的自噬活性如何，只有当接穗的自噬缺陷时，才会在叶片中出现 -Zn 诱导的黄化。这一数据表明，根细胞自噬降解所提供的 Zn 不能有助于抑制叶片中的黄化。因此，地上部分的自噬对于控制叶片中 -Zn 诱导的黄化是至关重要的。总之，结合我们最近的研究结果，我们得出结论，自噬降解提供 Zn 的机制不是在整个植物中系统性的，而是局部的系统。
