Ultraviolet-B light (UV-B) is an inherent part of sunlight, which has significant biological effects on plants. Low level, non-damaging UV-B serves as a photomorphogenic signal to regulate photomorphogenesis. UVR8 (UV RESISTANCE LOCUS 8) is a UV-B photoreceptor that mediates light responses in plant. The mechanism by which UVR8 triggers UV-B photomophogenic responses in the nucleus and whether or not UVR8 interacts with transcription factors to directly regulate transcription is still unknown. 

　　A group led by Dr Hongtao Liu from CAS Center for Excellence in Molecular Plant Sciences/Shanghai Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Science (CAS) provides evidence that UVR8 interacts with WRKY36 to regulate photomorphogeneis in response to UV-B light. 

　　Their results demonstrate 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. They 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. Their 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. 

This work entitled “UVR8 interacts with BES1 and BIM1 to regulate transcription and photomorphogenesis in Arabidopsis” has been published online in Developmental Cell on February 1st. The research was funded by NSFC, MOST and CAS. 

　　A hypothetical model depicting UVR8 acts with BES1/BIM1 to regulate transcription and photomorphogenesis in Arabidopsis.  

　　CONTACT: 

　　Dr. Hongtao Liu, PhD, Professor

　　National Key Laboratory of Plant Molecular Genetics

　　CAS Center for Excellence in Molecular Plant Sciences

　　Institute of Plant Physiology and Ecology (SIPPE)

　　Chinese Academy of science (CAS)

　　+86-21-54924291

　　Email: htliu@sibs.ac.cn