Toledo-Ortiz Gabriela, Johansson Henrik, Lee Keun Pyo, Bou-Torrent Jordi, Stewart Kelly, Steel Gavin, Rodríguez-Concepción Manuel, Halliday Karen J
Institute of Structural and Molecular Biology, SynthSys, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Structural and Molecular Biology, SynthSys, University of Edinburgh, Edinburgh, United Kingdom; Plant Physiology, Justus Liebig University, Senckernbergstr, Giessen, Germany.
PLoS Genet. 2014 Jun 12;10(6):e1004416. doi: 10.1371/journal.pgen.1004416. eCollection 2014 Jun.
The ability to interpret daily and seasonal alterations in light and temperature signals is essential for plant survival. This is particularly important during seedling establishment when the phytochrome photoreceptors activate photosynthetic pigment production for photoautotrophic growth. Phytochromes accomplish this partly through the suppression of phytochrome interacting factors (PIFs), negative regulators of chlorophyll and carotenoid biosynthesis. While the bZIP transcription factor long hypocotyl 5 (HY5), a potent PIF antagonist, promotes photosynthetic pigment accumulation in response to light. Here we demonstrate that by directly targeting a common promoter cis-element (G-box), HY5 and PIFs form a dynamic activation-suppression transcriptional module responsive to light and temperature cues. This antagonistic regulatory module provides a simple, direct mechanism through which environmental change can redirect transcriptional control of genes required for photosynthesis and photoprotection. In the regulation of photopigment biosynthesis genes, HY5 and PIFs do not operate alone, but with the circadian clock. However, sudden changes in light or temperature conditions can trigger changes in HY5 and PIFs abundance that adjust the expression of common target genes to optimise photosynthetic performance and growth.
解读光和温度信号的日常及季节性变化的能力对植物生存至关重要。这在幼苗建立期间尤为重要，此时光敏色素光感受器会激活光合色素的产生以实现光自养生长。光敏色素部分通过抑制光敏色素互作因子（PIFs）来实现这一点，PIFs是叶绿素和类胡萝卜素生物合成的负调控因子。而bZIP转录因子长下胚轴5（HY5）作为一种有效的PIF拮抗剂，会响应光照促进光合色素积累。在这里，我们证明，通过直接靶向一个共同的启动子顺式元件（G-box），HY5和PIFs形成了一个对光和温度信号有响应的动态激活-抑制转录模块。这种拮抗调节模块提供了一种简单、直接的机制，通过该机制环境变化可以重新引导对光合作用和光保护所需基因的转录控制。在光色素生物合成基因的调控中，HY5和PIFs并非单独起作用，而是与生物钟协同作用。然而，光照或温度条件的突然变化会引发HY5和PIFs丰度的变化，从而调整共同靶基因的表达以优化光合性能和生长。
