拟南芥WOX7调控侧根发育信号通路的研究

Root is critically important for plant growth, as it is the primary organ for uptake of nutrients and water as well as for anchorage. To meet the needs of a growing shoot, the root system has to increase its total surface area, which is accomplished mainly through lateral root formation and elongation. Lateral root formation is regulated not only by intrinsic factors, such as hormones, but also by extrinsic factors such as nutrient and water status. Sugar is a well-documented regulator on lateral root development. Most researches are focus on how sugar regulates lateral root development through auxin biosynthesis or signalling. Based on proposer’s previous research, transcriptional factor WOX7 in Arabidopsis was demonstrated as a negative regulator in lateral root development. The expression of WOX7 was enhanced by sugar level. Evidences showed that it is not auxin signalling pathway mediated the sugar regulated WOX7 expression, and the regulating mechanism remain unknown. This project will establish a Promoter WOX7: WOX7: GFP EMS mutant library for screening and identifying regulators on WOX7 expression, especially the genes regulating WOX7 expression in sugar signalling pathway. Following gene functional analysis of these genes will reveal how WOX7 expression is regulated in lateral root development. In the meantime, this project will identify the interaction protein of WOX7 by IP-MS to reveal how WOX7 regulates downstream genes as well. From the above, this project will provide a new view of how WOX7 signalling pathway regulated lateral root development. To emphasize, it will reveal a new mechanism on sugar regulated lateral root development and how plants adapt their root architecture to nutrient status.

侧根是根系的重要组成部分，对植物的生存和生长起着重要的作用。侧根的发生发育受到植物内源激素，外部环境和营养供应的共同调节。糖对侧根发育的调节机制的研究多集中于其如何通过生长素途径调控侧根发育，但对生长素之外的途径知之甚少。申请人发现，拟南芥中糖通过调控转录因子WOX7的表达调节侧根发育，且糖对WOX7的调控独立于生长素途径。本项目将在此基础上，通过构建proWOX7:WOX7: GFP EMS诱变突变体库，筛选和定位WOX7基因的上游调控基因，深入研究WOX7响应糖信号调控侧根发育的分子机制。同时，本研究还将利用免疫沉淀-质谱分析，筛选WOX7互作蛋白，解析WOX7在转录水平控制下游基因表达的机制。综上所述，本研究借助正向和反向遗传学手段，深入研究WOX7参与糖信号对侧根发育的调控机制，从而为生产实践中优化水肥管理和良种培育提供理论基础。

根是植物的重要器官，具有吸收水分、养料和锚定植物的作用，同时根系还参与了植物抗逆、抗病等重要生理反应，对植物的生存和生长至关重要，因此研究根的发育，了解调控根系包括侧根发育的调节机制，对于培育营养高效、高抗新品种，促进农业可持续发展具有重要意义。本研究通过构建proWOX7:WOX7:GFP EMS诱变突变体库和iws7-2 suppressors突变体库，筛选和定位了三个与WOX7相关的突变基因IWS7, IWSS36和 IWSS130。iws7的表型分析说明IWS7同时调节主根和侧根发育，它的表达与WOX7一样受到糖信号调节；而遗传学分析表明IWSS36和IWSS130在根系发育调控网络中处于IWS7下游。这些基因的发现为进一步了解根系发育调控机制和良种培育提供理论基础和基因资源。