UV‐B photoreceptor UVR8 interacts with MYB73/MYB77 to regulate auxin responses and lateral root development

First author: Yu Yang; Affiliations: CAS Center for Excellence in Molecular Plant Sciences (中科院分子植物科学卓越创新中心): Shanghai, China

Corresponding author: Hongtao Liu

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.

植物中，UV‐B光受体UVR8介导多个UV-B响应，但其在根发育中的作用还不清楚。本文中，作者的研究显示UV‐B会抑制拟南芥的侧根发育，该过程依赖于UVR8。单体UVR8会以组织自主性方式抑制生长素响应，从而调控侧根的生长。全基因组范围的基因表达分析显示生长素和UV‐B辐射拮抗调控生长素调节相关基因的表达。作者进一步的研究显示UVR8能够物理上与MYB73/MYB77发生互作，且该互作依赖于UV‐B辐射。UVR8通过调控MYB73/MYB77来抑制侧根的发育。当UVR8被UV‐B辐射激活时，其会定位于核中，并且抑制MYB73/MYB77的DNA结合活性，直接抑制这两个转录因子靶向的生长素响应基因的转录。本文的结果揭示了UV‐B辐射和UVR8对于植物地上部分的形态发生和地下部分根的发育都是至关重要的。依赖于UV‐B的UVR8-MYB73/MYB77互作作为一个重要模块协调光照和生长素信号转导对于植物生长发育的影响，代表了植物中一个新的UVR8信号通路机制。

通讯：刘宏涛 (http://lht.sippe.ac.cn)

个人简介：2002-2005年，河北师范大学，博士；2005-2010年，美国加州大学洛杉矶分校，博士后。

研究方向：以拟南芥和玉米为对象，围绕光信号调控植物发育的分子机制，光信号传递的机制，及光信号转导与其他内外源信号的交叉整合展开植物分子发育研究。

doi: https://doi.org/10.15252/embj.2019101928

Journal: the EMBO Journal

Published date: November 28, 2019

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