Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
Philos Trans R Soc Lond B Biol Sci. 2020 Jun 22;375(1801):20190406. doi: 10.1098/rstb.2019.0406. Epub 2020 May 4.
The photosynthetic apparatus is one of the major primary sensors of the plant's external environment. Changes in environmental conditions affect the balance between harvested light energy and the capacity to deal with excited electrons in the stroma, which alters the redox homeostasis of the photosynthetic electron transport chain. Disturbances to redox balance activate photosynthetic regulation mechanisms and trigger signalling cascades that can modify the transcription of nuclear genes. HO and oxylipins have been identified as especially prominent regulators of gene expression in response to excess light stress. This paper explores the hypothesis that photosynthetic imbalance triggers specific signals that target discrete gene profiles and biological processes. Analysis of the major retrograde signalling pathways engaged during high light stress and recovery demonstrates both specificity and overlap in gene targets. This work reveals distinct, time-resolved profiles of gene expression that suggest a regulatory interaction between rapidly activated abiotic stress response and induction of secondary metabolism and detoxification processes during recovery. The findings of this study show that photosynthetic electron transport provides a finely tuned sensor for detecting and responding to the environment through chloroplast retrograde signalling. This article is part of the theme issue 'Retrograde signalling from endosymbiotic organelles'.
光合作用器是植物外部环境的主要初级传感器之一。环境条件的变化会影响到在基质中收获的光能和处理激发电子的能力之间的平衡，从而改变光合作用电子传递链的氧化还原平衡。氧化还原平衡的破坏会激活光合作用调节机制，并引发信号级联反应，从而改变核基因的转录。HO 和氧化脂类已被确定为响应过量光胁迫时基因表达的特别重要的调节因子。本文探讨了这样一种假设，即光合作用失衡会引发针对特定基因谱和生物过程的特定信号。对高光胁迫和恢复过程中涉及的主要逆行信号通路的分析表明，基因靶标既有特异性又有重叠。这项工作揭示了特定的、时间分辨的基因表达谱，表明在恢复过程中，快速激活的非生物胁迫反应与次生代谢物和解毒过程的诱导之间存在调节相互作用。本研究的结果表明，光合作用电子传递为通过叶绿体逆行信号检测和响应环境提供了一个精细调节的传感器。本文是主题为“来自共生细胞器的逆行信号”的一部分。
