Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, California 92521.
Department of Molecular and Cellular Biology, University of California, Davis, California 95616.
Plant Physiol. 2020 Jul;183(3):1268-1280. doi: 10.1104/pp.20.00090. Epub 2020 May 19.
Exquisitely regulated plastid-to-nucleus communication by retrograde signaling pathways is essential for fine-tuning of responses to the prevailing environmental conditions. The plastidial retrograde signaling metabolite methylerythritol cyclodiphosphate (MEcPP) has emerged as a stress signal transduced into a diverse ensemble of response outputs. Here, we demonstrate enhanced phytochrome B protein abundance in red light-grown MEcPP-accumulating mutant Arabidopsis () plants relative to wild-type seedlings. We further establish MEcPP-mediated coordination of phytochrome B with auxin and ethylene signaling pathways and uncover differential hypocotyl growth of red light-grown seedlings in response to these phytohormones. Genetic and pharmacological interference with ethylene and auxin pathways outlines the hierarchy of responses, placing ethylene epistatic to the auxin signaling pathway. Collectively, our findings establish a key role of a plastidial retrograde metabolite in orchestrating the transduction of a repertoire of signaling cascades. This work positions plastids at the zenith of relaying information coordinating external signals and internal regulatory circuitry to secure organismal integrity.
通过逆行信号通路进行的高度调节的质体-核通讯对于微调对流行环境条件的反应至关重要。质体逆行信号代谢物甲基赤藓醇环二磷酸（MEcPP）已成为一种应激信号，可转导为多种反应输出。在这里，我们证明了与野生型幼苗相比，在红光生长的 MEcPP 积累突变体拟南芥（）植物中，phytochrome B 蛋白丰度增加。我们进一步建立了 MEcPP 介导的 phytochrome B 与生长素和乙烯信号通路的协调，并揭示了这些植物激素对红光生长的幼苗下胚轴生长的差异。对乙烯和生长素途径的遗传和药理学干扰概述了反应的层次结构，将乙烯置于生长素信号途径的上位。总的来说，我们的发现确立了质体逆行代谢物在协调一系列信号级联转导中的关键作用。这项工作将质体置于中继信息的顶点，协调外部信号和内部调节电路，以确保生物体的完整性。
