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  • Disruption of microtubules in plants suppresses macroautophagy and triggers starch excess-associated chloroplast autophagy.

Disruption of microtubules in plants suppresses macroautophagy and triggers starch excess-associated chloroplast autophagy.

Autophagy (2015-11-15)
Yan Wang, Xiyin Zheng, Bingjie Yu, Shaojie Han, Jiangbo Guo, Haiping Tang, Alice Yunzi L Yu, Haiteng Deng, Yiguo Hong, Yule Liu
ABSTRACT

Microtubules, the major components of cytoskeleton, are involved in various fundamental biological processes in plants. Recent studies in mammalian cells have revealed the importance of microtubule cytoskeleton in autophagy. However, little is known about the roles of microtubules in plant autophagy. Here, we found that ATG6 interacts with TUB8/β-tubulin 8 and colocalizes with microtubules in Nicotiana benthamiana. Disruption of microtubules by either silencing of tubulin genes or treatment with microtubule-depolymerizing agents in N. benthamiana reduces autophagosome formation during upregulation of nocturnal or oxidation-induced macroautophagy. Furthermore, a blockage of leaf starch degradation occurred in microtubule-disrupted cells and triggered a distinct ATG6-, ATG5- and ATG7-independent autophagic pathway termed starch excess-associated chloroplast autophagy (SEX chlorophagy) for clearance of dysfunctional chloroplasts. Our findings reveal that an intact microtubule network is important for efficient macroautophagy and leaf starch degradation.

MATERIALS
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Methyl viologen dichloride hydrate, 98%
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Anti-Luciferase antibody produced in rabbit, IgG fraction of antiserum, buffered aqueous solution
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Triton X-100, laboratory grade
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Triton X-100, for molecular biology