Sugliani Matteo, Abdelkefi Hela, Ke Hang, Bouveret Emmanuelle, Robaglia Christophe, Caffarri Stefano, Field Ben
Aix Marseille University, Biologie Végétale et Microbiologie Environnementales UMR 7265, Laboratoire de Génétique et Biophysique des Plantes, Marseille F-13009, France CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, Marseille F-13009, France CEA, Bioscience and Biotechnology Institute of Aix-Marseille, Marseille F-13009, France.
Aix Marseille University, Biologie Végétale et Microbiologie Environnementales UMR 7265, Laboratoire de Génétique et Biophysique des Plantes, Marseille F-13009, France CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, Marseille F-13009, France CEA, Bioscience and Biotechnology Institute of Aix-Marseille, Marseille F-13009, France University of Tunis El Manar, Faculté des Sciences de Tunis, Laboratory of Molecular Genetics, Immunology, and Biotechnology, 2092 El Manar Tunis, Tunisia.
Plant Cell. 2016 Mar;28(3):661-79. doi: 10.1105/tpc.16.00045. Epub 2016 Feb 23.
The chloroplast originated from the endosymbiosis of an ancient photosynthetic bacterium by a eukaryotic cell. Remarkably, the chloroplast has retained elements of a bacterial stress response pathway that is mediated by the signaling nucleotides guanosine penta- and tetraphosphate (ppGpp). However, an understanding of the mechanism and outcomes of ppGpp signaling in the photosynthetic eukaryotes has remained elusive. Using the model plant Arabidopsis thaliana, we show that ppGpp is a potent regulator of chloroplast gene expression in vivo that directly reduces the quantity of chloroplast transcripts and chloroplast-encoded proteins. We then go on to demonstrate that the antagonistic functions of different plant RelA SpoT homologs together modulate ppGpp levels to regulate chloroplast function and show that they are required for optimal plant growth, chloroplast volume, and chloroplast breakdown during dark-induced and developmental senescence. Therefore, our results show that ppGpp signaling is not only linked to stress responses in plants but is also an important mediator of cooperation between the chloroplast and the nucleocytoplasmic compartment during plant growth and development.
叶绿体起源于真核细胞对一种古老光合细菌的内共生。值得注意的是，叶绿体保留了由信号核苷酸鸟苷五磷酸和四磷酸（ppGpp）介导的细菌应激反应途径的元件。然而，对于光合真核生物中ppGpp信号传导的机制和结果仍不清楚。利用模式植物拟南芥，我们表明ppGpp在体内是叶绿体基因表达的有效调节因子，可直接减少叶绿体转录本和叶绿体编码蛋白的数量。然后我们继续证明不同植物RelA SpoT同源物的拮抗功能共同调节ppGpp水平以调控叶绿体功能，并表明它们是黑暗诱导衰老和发育衰老期间植物最佳生长、叶绿体体积和叶绿体解体所必需的。因此，我们的结果表明，ppGpp信号传导不仅与植物的应激反应有关，而且是植物生长和发育过程中叶绿体与核质区室之间合作的重要介质。
