BZR1 mediates brassinosteroid-induced autophagy and nitrogen starvation tolerance in tomato.
BZR1 mediates brassinosteroid-induced autophagy and nitrogen starvation tolerance in tomato.
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BZR1 介导番茄中油菜素类固醇诱导的自噬和氮饥饿
DOI：
10.1104/pp.18.01028
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发表时间：
2018
期刊：
影响因子：
7.4
通讯作者：
Zhou Jie
中科院分区：
文献类型：
--
作者：
Wang Yu;Cao Jia-Jian;Wang Kai-Xin;Xia Xiao-Jian;Shi Kai;Zhou Yan-Hong;Yu Jing-Quan;Zhou Jie
自噬是一种天然的细胞破坏机制，在植物发育和逆境反应中起着至关重要的作用。已知自噬可受到多种分子过程的刺激或抑制，但植物激素信号在自噬中的作用尚不清楚。在这里，我们证明了自噬相关基因（ATGs）的转录本和自噬体的形成是由油菜素内酯（BR）水平的提高触发的。此外，BR激活的转录因子brassinazol -resistant1 （BZR1）是BR信号通路的正调节因子，参与BR诱导的自噬。BR处理增强了atgsinbzr1过表达植物的自噬体形成和转录本，而BR的作用在bzr1沉默的植物中受到抑制。酵母单杂交分析和染色质免疫沉淀结合定量聚合酶链反应表明，BZR1与atg2和atg6的启动子结合。在atg2 -和atg6沉默的植物中，br诱导的自噬体的形成减少。此外，外源施用BR提高了氮饥饿条件下叶绿素含量和自噬体的形成，减少了泛素化蛋白的积累。氮饥饿条件下，bzr1 -和bzr1 - 1d -过表达植株的叶片褪绿和叶绿素降解加剧，BR生物合成突变体的影响减轻。与此同时，氮饥饿诱导的atg表达和自噬体形成在bzr1沉默和bzr1 - 1d过表达的植株中均受到抑制，而在bzr1 - 1d过表达的植株中则有所增加。综上所述，我们的研究结果表明，bzr1依赖的BR信号上调atg的表达和自噬体的形成，这在番茄（Solanum lycopersicum）植物对氮饥饿的响应中起着关键作用。
Autophagy, an innate cellular destructive mechanism, plays crucial roles in plant development and responses to stress. Autophagy is known to be stimulated or suppressed by multiple molecular processes, but the role of phytohormone signaling in autophagy is unclear. Here, we demonstrate that the transcripts of autophagy-related genes (ATGs) and the formation of autophagosomes are triggered by enhanced levels of brassinosteroid (BR). Furthermore, the BR-activated transcription factor brassinazole-resistant1 (BZR1), a positive regulator of the BR signaling pathway, is involved in BR-induced autophagy. Treatment with BR enhanced the formation of autophagosomes and the transcripts ofATGsinBZR1-overexpressing plants, while the effects of BR were compromised inBZR1-silenced plants. Yeast one-hybrid analysis and chromatin immunoprecipitation coupled with quantitative polymerase chain reaction revealed that BZR1 bound to the promoters ofATG2andATG6. The BR-induced formation of autophagosomes decreased inATG2- andATG6-silenced plants. Moreover, exogenous application of BR enhanced chlorophyll content and autophagosome formation and decreased the accumulation of ubiquitinated proteins under nitrogen starvation. Leaf chlorosis and chlorophyll degradation were exacerbated inBZR1-silenced plants and the BR biosynthetic mutantd^imbut were alleviated inBZR1- andBZR1-1D-overexpressing plants under nitrogen starvation. Meanwhile, nitrogen starvation-induced expression ofATGsand autophagosome formation were compromised in bothBZR1-silenced andd^implants but were increased inBZR1- andBZR1-1D-overexpressing plants. Taken together, our results suggest that BZR1-dependent BR signaling up-regulates the expression ofATGsand autophagosome formation, which plays a critical role in the plant response to nitrogen starvation in tomato (Solanum lycopersicum).