细胞伸长是植物生长发育的基础，而细胞伸长必需依赖细胞壁不断地扩展和重构。目前植物已进化出一套严格监控细胞壁状态的分子机制以协调这两个过程，其中，BR信号途径在这个过程中发挥着重要作用。然而，目前关于BRs调控细胞壁扩展和重构与细胞伸长之间关系的分子机制还知之甚少。我们前期研究表明，C3H15参与细胞壁形成并显著调控细胞伸长；与BIN2互作且能被BIN2磷酸化；与BZR1和BES1在转录水平上直接相互拮抗，也能直接抑制THE1的表达；直接抑制或激活与细胞伸长和BRs合成相关基因的表达，推测它可能整合BR和THE1途径调控细胞伸长。本项目以此为切入点，挖掘C3H15直接靶基因或调控它的基因，揭示它与调控枢纽BZR1和BES1之间的相互关系，解析它介导THE1途径的功能，阐明它整合BR和THE1途径调控细胞壁扩展与重构及细胞伸长的分子机制，这将为丰富人们认识植物BRs生理功能奠定基础。

Cell elongation is the basis of plant growth and development, and plant cell elongation depends on the expansion and remodeling of the cell wall. To coordinate these two processes, surveillance mechanisms have evolved to monitor the state of the cell wall. The brassinosteroid (BR) hormone signaling pathway plays an essential role in the cell elongation control and regulates the expression of a plethora of cell wall-related genes. However, the molecular mechanism of BR-mediated wall remodeling and cell elongation is not fully clarified. We have previously shown that the CCCH transcription factor C3H15 was observably involved in the cell wall formation and hypocotyl elongation, C3H15 is a substrate of BIN2 kinase, C3H15 directly suppresses BZR1, BES1 and THE1 expression, and direct suppression or activation of C3H15 on the expression of several cell elongation-associated genes or BRs biosynthetic genes is dependent on BRs. These results indicated that C3H15 might regulate the cell elongation via integrating BR and THE1 Pathway during cell elongation. Based on the above results, this project aims to reveal the relationship between C3H15, BZR1 and BES1 in the BR-mediated wall remodeling and cell elongation, characterizes the biological role of C3H15 in THE1 pathway, and thus elucidates the molecular mechanism that C3H15 regulates the wall remodeling and cell elongation via integrating BR and THE1 Pathway during cell elongation. The results in this project will be important to further gain a comprehensive view of BRs biological functions.