Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Sciences, Department of Biology, School of Life Sciences, Southern University of Science and Technology, 518055, Shenzhen, China.
J Integr Plant Biol. 2023 Jul;65(7):1703-1716. doi: 10.1111/jipb.13483. Epub 2023 Apr 21.
Plants have adopted versatile scaffold proteins to facilitate the crosstalk between multiple signaling pathways. Leaf senescence is a well-programmed developmental stage that is coordinated by various external and internal signals. However, the functions of plant scaffold proteins in response to senescence signals are not well understood. Here, we report that the scaffold protein RACK1A (RECEPTOR FOR ACTIVATED C KINASE 1A) participates in leaf senescence mediated by ethylene signaling via the coordination of the EIN3-miR164-ORE1 transcriptional regulatory cascade. RACK1A is a novel positive regulator of ethylene-mediated leaf senescence. The rack1a mutant exhibits delayed leaf senescence, while transgenic lines overexpressing RACK1A display early leaf senescence. Moreover, RACK1A promotes EIN3 (ETHYLENE INSENSITIVE 3) protein accumulation, and directly interacts with EIN3 to enhance its DNA-binding activity. Together, they then associate with the miR164 promoter to inhibit its transcription, leading to the release of the inhibition on downstream ORE1 (ORESARA 1) transcription and the promotion of leaf senescence. This study reveals a mechanistic framework by which RACK1A promotes leaf senescence via the EIN3-miR164-ORE1 transcriptional cascade, and provides a paradigm for how scaffold proteins finely tune phytohormone signaling to control plant development.
植物采用了多功能支架蛋白来促进多种信号通路之间的串扰。叶片衰老是一个经过精心编程的发育阶段，由各种外部和内部信号协调。然而，植物支架蛋白对衰老信号的反应功能还不是很清楚。在这里，我们报告说支架蛋白 RACK1A（RECEPTOR FOR ACTIVATED C KINASE 1A）通过协调 EIN3-miR164-ORE1 转录调控级联，参与乙烯信号介导的叶片衰老。RACK1A 是乙烯介导的叶片衰老的一个新的正调控因子。rack1a 突变体表现出叶片衰老延迟，而过表达 RACK1A 的转基因系则表现出叶片衰老提前。此外，RACK1A 促进 EIN3（ETHYLENE INSENSITIVE 3）蛋白积累，并直接与 EIN3 相互作用以增强其 DNA 结合活性。它们共同与 miR164 启动子结合，抑制其转录，从而释放对下游 ORE1（ORESARA 1）转录的抑制作用，并促进叶片衰老。这项研究揭示了 RACK1A 通过 EIN3-miR164-ORE1 转录级联促进叶片衰老的机制框架，并为支架蛋白如何精细调节植物激素信号以控制植物发育提供了范例。
