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 function of UVR8 in regulating root development has not previously been investigated.

　　A group led by Dr Hongtao Liu from the CAS Center for Excellence in Molecular Plant Sciences provides evidence that UVR8 interacts with MYB73 and MYB77 to regulate lateral root development in response to UV-B light.

　　Their results demonstrate that UV-B light inhibits Arabidopsis lateral root growth in a UVR8-dependent manner. Monomeric UVR8 inhibits auxin responses in a tissue-autonomous manner and thereby regulates lateral root growth. Genome-wide gene expression analysis demonstrated that auxin and UV-B irradiation antagonistically regulate auxin-regulated gene expression. We further show that UVR8 physically interacts with MYB73/MYB77 (MYB DOMAIN PROTEIN 73/77) in a UV-B-dependent manner. UVR8 inhibits lateral root development via regulation of MYB73/MYB77. When activated by UV-B light, UVR8 localizes to the nucleus and inhibits the DNA-binding activities of MYB73/MYB77 and directly represses the transcription of their target auxin-responsive genes. Our results demonstrate that UV-B light and UVR8 are critical for both shoot morphogenesis and root development. The UV-B-dependent interaction of UVR8 and MYB73/MYB77 serves as an important module that integrates light and auxin signaling and represents a new UVR8 signaling mechanism in plants.

　　This work entitled “UV-B photoreceptor UVR8 interacts with MYB73/MYB77 to regulate auxin responses and lateral root development” has been published online in EMBO J on November 28th 2019. The research was funded by NSFC, MOST and CAS.

　　A hypothetical model depicting how UVR8 acts with MYB73/MYB77 to regulate auxin signaling and UV-B photomorphogenesis in Arabidopsis.

　　Contact:

　　Link: https://www.embopress.org/doi/10.15252/embj.2019101928 

　　Contact:

　　Dr. Hongtao Liu, Professor

　　Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences/Shanghai Institute of Plant Physiology and Ecology (SIPPE), Chinese Academic of Sciences

　　Tel: +86-21-54924291

　　Email: htliu@sibs.ac.cn