Light is the most important environmental factor affecting many aspects of plant development. In this study, we report that B-box protein 11 (BBX11) acts as a positive regulator of red light signaling. BBX11 loss-of-function mutant seedlings display significantly elongated hypocotyls under conditions of both red light and long day, whereas BBX11 overexpression causes markedly shortened hypocotyls under various light states. BBX11 binds to the HY5 promoter to activate its transcription, while both BBX21 and HY5 associate with the promoter of BBX11 to positively regulate its expression. Taken together, our results reveal positive feedback regulation of photomorphogenesis consisting of BBX11, BBX21, and HY5, thus substantiating a transcriptional regulatory mechanism in the response of plants to light during normal development.

光是影响植物发育许多方面的最重要的环境因素。在这项研究中，我们报告 B-box 蛋白 11 (BBX11) 作为红光信号传导的正调节因子。 BBX11功能丧失突变体幼苗在红光和长日照条件下均表现出显着拉长的下胚轴，而BBX11过表达则导致在各种光状态下下胚轴显着缩短。 BBX11与HY5启动子结合以激活其转录，而BBX21和HY5均与BBX11的启动子结合以正向调节其表达。综上所述，我们的结果揭示了由 BBX11、BBX21 和 HY5 组成的光形态发生的正反馈调节，从而证实了植物在正常发育过程中对光反应的转录调节机制。