Developmental Cell∣中科院劉宏濤研究組揭示了UV-B與BR信號途徑協同調控植物下胚軸伸長的新機制

2018年2月2日，Developmental Cell雜誌在線發表了中國科學院上海生命科學研究院植物生理生態研究所劉宏濤研究組題為「UVR8 Interacts with BES1 and BIM1 to Regulate Transcription and Photomorphogenesis in Arabidopsis」的研究論文，文章揭示了紫外光UV-B與內源油菜素甾醇信號協同調控生長的新機制。

摘要：

已知UV-B光抑制植物生長，但其機理尚不清楚。UVR8是植物中介導UV-B光反應的UV-B光受體。本文中，UV-B通過抑制科院促進植物植物生長的BR信號來抑制植物生長。UVR8與功能性去磷酸化的BES1和轉錄因子BIM1在物理上相互作用，介導BR調節的基因表達和植物生長以抑制其活性。全基因組基因表達分析，鑒定了依賴BES1的，UV-B調控的轉錄組，其中富含與細胞延伸和植物生長有關的基因。進一步的結果表明，UVB激活和細胞核定位的UVR8抑制BES1/BIM1的DNA結合活性，直接調節生長相關基因的轉錄。因此，我們的研究結果表明，UVR8-BES1/BIM1相互作用代表了植物早期的光受體信號傳導機制，並且是整合光和BR信號的重要模塊。

Abstract：

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.

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