UVR8 Interacts with BES1 and BIM1 to Regulate Transcription and Photomorphogenesis in Arabidopsis

Publication date: Available online 1 February 2018
Source:Developmental Cell
Author(s): Tong Liang, Shenglin Mei, Chen Shi, Yu Yang, Yao Peng, Libang Ma, Fei Wang, Xu Li, Xi Huang, Yanhai Yin, Hongtao Liu
UV-B light (UV-B radiation) is known to inhibit plant growth, but the mechanism is not well understood. UVR8 (UV RESISTANCE LOCUS 8) is a UV-B light photoreceptor that mediates UV-B light responses in plants. We report here that UV-B inhibits plant growth by repressing plant steroid hormone brassinosteroid (BR)-promoted plant growth. UVR8 physically interacts with the functional dephosphorylated BES1 (BRI1-EMS-SUPPRESSOR1) and BIM1 (BES1-INTERACTING MYC-LIKE 1) transcription factors that mediate BR-regulated gene expression and plant growth to inhibit their activities. Genome-wide gene expression analysis defined a BES1-dependent UV-B-regulated transcriptome, which is enriched with genes involved in cell elongation and plant growth. We further showed that UV-B-activated and nucleus-localized UVR8 inhibited the DNA-binding activities of BES1/BIM1 to directly regulate transcription of growth-related genes. Our results therefore establish that UVR8-BES1/BIM1 interaction represents an early photoreceptor signaling mechanism in plants and serves as an important module integrating light and BR signaling.

Graphical abstract

Teaser

UV-B light is known to inhibit plant growth, but the mechanism is not well understood. Liang et al. show that UV-B photoreceptor UVR8 physically interacts with BIM1 and BES1, transcription factors mediating brassinosteroid signaling, to repress their DNA-binding activities and thus affect growth and photomorphogenesis.


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