Abstract：
Light is one of the most essential environmental factors that tightly and precisely control various physiological and developmental processes in plants. B-box CONTAINING PROTEINs (BBXs) play central roles in the regulation of light-dependent development. In this study, we report that BBX9 is a positive regulator of light signaling. BBX9 interacts with the red light photoreceptor PHYTOCHROME B (phyB) and transcription factors PHYTOCHROME-INTERACTING FACTORs (PIFs). phyB promotes the stabilization of BBX9 in light, while BBX9 inhibits the transcriptional activation activity of PIFs. In turn, PIFs directly bind to the promoter of BBX9 to repress its transcription. On the other hand, BBX9 associates with the positive regulator of light signaling, BBX21, and enhances its biochemical activity. BBX21 associates with the promoter regions of BBX9 and transcriptionally up-regulates its expression. Collectively, this study unveiled that BBX9 forms a negative feedback loop with PIFs and a positive one with BBX21 to ensure that plants adapt to fluctuating light conditions.
摘要：
光是最重要的环境因素之一，可以精确地控制植物的各种生理和发育过程。含有B盒蛋白质(BBXs)在光依赖性发育的调节中起核心作用。在这项研究中,我们报告说，BBX9是光信号的正调节剂。BBX9与红光光感受器植物色素B（phyB）和转录因子植物色素相互作用因子（PIFs）相互作用。phyB促进BBX9在光照下的稳定，而BBX9抑制PIF的转录激活活性。反过来,PIF直接与BBX9的启动子结合以抑制其转录。另一方面,BBX9与光信号的正调节剂相关，BBX21，并增强其生化活性。BBX21与BBX9的启动子区结合并在转录上上调其表达。总的来说，这项研究揭示了BBX9与PIF形成负反馈回路，与BBX21形成正反馈回路，以确保植物适应波动的光照条件。
