UV‐B photoreceptor UVR8 interacts with MYB73/MYB77 to regulate auxin responses and lateral root development. (28th November 2019) - Yang, Yu
Abstract: The UV‐B photoreceptor UVR8 mediates multiple UV‐B responses in plants, but the function of UVR8 in regulating root development has not previously been investigated. Here, we show 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. Synopsis: UV‐B light inhibits auxin signaling in plants to regulate light‐dependent plant growth. New data show that UV‐B photoreceptor UVR8 coordinates light‐ and auxin‐dependent root and shoot development via inhibition of auxin‐responsive transcription factors MYB73/MYB77. UV‐B inhibits lateral root growth in a UVR8‐dependent manner. Monomeric UVR8 inhibits auxin responses in the root. UVR8 interacts with MYB73/MYB77 upon UV‐B‐mediated activation. UVR8 inhibits the DNA‐binding activity of MYB73/MYB77 to repress the expression of auxin‐responsive genes. Abstract : The UV‐B light inhibits auxin‐induced root and shoot growth via direct interaction between the photoreceptor UVR8 and auxin‐responsive transcription factors MYB73/MYB77.