拟南芥C3H15整合BR和THE1途径调控细胞伸长的分子机制

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.

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。

油菜素内酯（BRs）和THE1途径在植物细胞伸长过程中交叉发挥关键作用，但它们的分子调控机制还不十分清楚。本项目通过大量遗传生化证据证实拟南芥C3H15能够整合BR和THE1途径精确调控细胞伸长，取得的主要结果如下：（1）C3H14和C3H15冗余负调控茎和下胚轴细胞伸长；（2）C3H15是BR信号途径的一个负调控因子，能够被BR信号关键组分BIN2磷酸化，介导一条不依赖BZR1/BES1的通路；（3）C3H15和BZR1/BES1互为靶基因，在转录水平上互相拮抗共同调控BR信号和细胞伸长；（4）C3H15通过抑制THE1信号调控细胞伸长。在全部完成既定任务之外，本项目对原有研究内容进行适度延伸，发现C3H14和C3H15主要通过WRKY33途径介导JA/ET信号正调控灰霉病侵染。在本项目资助下发表相关SCI论文 10 篇，包括Plant Physiology（2篇），Plant Cell and Environment, Horticulture Research, GCB Bioenergy（2篇），Frontiers in Plant Science（2篇），Annals of Botany 和Journal of Forestry Research，参编专著1部，申请专利2件，获得青岛市科学技术二等奖1项，获江苏省双创人才和国务院政府特殊津贴专家称号，完成了预期目标。同时，培养了3名青年科研骨干（1人由助研晋升为副研，2人博后出站留所工作）和2名研究生。