BR调控芥子油苷生物合成的机理研究

Glucosinolates(GS) are a group of secondary metabolites mainly existed in Brassicaceae plants. Glucosinolates and their degradation products are known to play important roles in plant interaction with herbivores and microorganisms. In addition, they are also important for human life because of the remarkable anti-carcinogenic activity of their hydrolysis products, isothiocyanates. The biosynthesis of glucosinolates is delicately modulated by multiple signals. Brassinosteroid(BR) is a kind of phytohormones whose signaling pathway is well elucidated. While BR's function in plant development and stress-resistance was widely reported, whether it regulates biosynthesis of secondary metabolites remains unknown. Our previous studies indicated that BR significantly inhibit the biosynthesis of glucosinolates, and BZR1/BES1,the two central transcriptional factors in BR signaling pathway, seemed to be involved in this process. In this project, we will use both GS-related and BR signaling mutants to identify the BR-regulated GS-genes and confirm BZR/BES1's role in the regulation of GS biosynthesis. Furthermore, combined with the molecular and genetic analysis, we will try to clarify the mechanisms by which BZR1/BES1 interact with GS-related MYB transcriptional factors to co-regulate GS biosynthesis. Our research will be potential for understanding the crosstalk between phytohormone signalling and GS regulatory network.

芥子油苷是主要存在于十字花科植物中的次生代谢物质，具有重要的生物学功能，如参与植物的防卫反应和抗癌活性等。芥子油苷的生物合成受到多种信号的调控，关于其调控网络的研究已成为该领域中的研究热点。 BR信号转导途径是研究得较为透彻的信号转导途径之一，它在植物生长发育和抗逆性中的作用的研究较为深入，但BR信号转导途径对次生代谢物质的调节作用的研究未见报道。我们前期研究表明BR能负向调控芥子油苷的生物合成，并且发现信号转导途径中的关键组分BZR1和BES1参与对芥子油苷的调控。本项目拟以拟南芥为材料，通过生理学、遗传学和分子生物学手段，确定芥子油苷合成途径中受BR调控的基因，进一步验证BZR1和BES1是否参与调控芥子油苷生物合成，以及阐明BZR1和BES1通过芥子油苷相关MYB类转录因子调控芥子油苷生物合成的分子机理，为植物激素信号和芥子油苷的调控网络之间的交叉互作研究提供理论依据。

芥子油苷是主要存在于十字花科植物中的次生代谢物质，具有重要的生物学功能，如参与植物的防卫反应和对人体的抗癌活性等。目前芥子油苷的调控网络研究已成为该领域的研究热点，并且许多研究发现芥子油苷的生物合成受到多种信号的调控。BR信号转导途径是研究的比较透彻的信号转导途径之一，尤其是BR在植物生长发育和抗逆性中作用的研究较为深入，但BR对次生代谢物质调节作用的研究未见报道。我们前期的研究发现BR负向调控芥子油苷的生物合成，BR信号转导途径中关键转录因子BZR1和BSE1参与对芥子油苷的调控，本次的研究我们通过分子生物学、遗传学、生理学等手段，发现芥子油苷合成途径中重要的转录因子MYB51和MYB29参与了BR负向调控芥子油苷的合成。在BR的信号激发下，去磷酸化得到活性的BZR1和BES1结合在MYB51和MYB29的启动子上，抑制了MYB51及MYB29的表达，从而负向调控芥子油苷的合成。本项工作解析了BR负向调控芥子油苷合成的分子机理，为植物激素信号和芥子油苷的调控网络间的交叉互作研究提供了理论依据。