On February 14, 2019, Professor Xing Wang Deng from Department of Biology, Southern University of Science and Technology (SUSTech) published an online research article entitled “B-box containing proteins BBX30 and BBX31, acting downstream of HY5, negatively regulate photomorphogenesis in Arabidopsis” in “Plant Physiology” journal. Senior Research Assistant Dr. Yueqing Heng and Visiting Scholar Dr. Fang Lin from the Institute of Plant and Food Science, Department of Biology, are the co-first authors; Professor Xing Wang Deng at SUSTech and Professor Dongqing Xu at Nanjing Agricultural University are the co-corresponding authors of the paper. Research Assistant Professor Dr. Yan Jiang, PhD student Tingting Yan, Senior Research Assistant Hongxia Lan, Post-doc Xianhai Zhao and Post-doc Hua Zhou at SUSTech are co-authors.

A working model depicting BBX30 and BBX31 in the regulation of photomorphogenesis.

Light is not only the major energy source for plants, but also acts as one of the most essential environmental factors affecting various physiological and developmental processes in plants. Light-mediated seedling development is coordinately controlled by a variety of key regulators. Here, we identified two B-box (BBX) containing proteins, BBX30 and BBX31, as repressors of photomorphogenesis. ELONGATED HYPOCOTYL 5 (HY5), a central regulator of light signaling, directly binds to the G-box cis-element present in the promoters of BBX30 and BBX31 and negatively controls their transcription levels in the light. Seedlings with mutations in BBX30 or BBX31 are hypersensitive to light, whereas the overexpression of BBX30 or BBX31 leads to hypo-photomorphogenic growth in the light. Furthermore, transgenic and phenotypic analysis revealed that the B-box domain of BBX30 or BBX31 is essential for their respective functioning in the regulation of photomorphogenic development in plants. In conclusion, BBX30 and BBX31 act as key negative regulators of light signaling, and their transcription is repressed by HY5 through directly associating with their promoters.

The study was supported by the Start-up Funding from SUSTech, National Natural Science Foundation of China, Peking University-Tsinghua Life Science Joint Center and China Postdoctoral Science Foundation.

Link to paper: http://www.plantphysiol.org/content/early/2019/02/14/pp.18.01244.