ABI5差异调控吲哚类和脂肪类芥子油苷合成的机理

Glucosinolates are a group of plant secondary metabolites with important biological functions. Glucosinolates and their degradation products are not only the flavor source of Brassica vegetable but also play an important role in lowing cancer risk and plant defense against pathogens and herbivores. The biosynthetic pathway of glucosinolate in Arabidopsis thaliana has been clarified and the regulatory role of MYB transcription factors in glucosinolate biosynthesis was well studied. However, upstream regulatory elements of MYB transcription factors have been rarely reported. ABA INSENSITIVE5 (ABI5), a basic leucine zipper transcription factor, is the common component in glucose and ABA signaling pathway. It contributes significantly to seed germination, plant growth, and stress response. Our previous studies have shown that ABI5 regulates glucosinolate biosynthesis by MYB transcription factors, and there is a difference in the regulatory pattern of ABI5 on indolic and aliphatic MYB transcription factors. In the present study, we aim to further elucidate the interaction between ABI5 and two types of MYB transcription factors, and clarify the regulatory mechanism of ABI5 on indolic and aliphatic glucosinolates by combining with genetic analysis, so as to illuminate the regulatory elements upstream of MYB transcription factors. It will provide innovative knowledge to glucosinolate regulatory network, and also lay the theoretical foundation for the improvement of the quality and resistance in Brassica crops through metabolic engineering of glucosinolate components and contents.

芥子油苷(GS)是一类具有重要生物学功能的植物次生代谢物质，参与植物的防卫反应，并具有抗癌活性，与芸薹属作物的品质和抗性相关。拟南芥中GS的合成途径已经得到解析，MYB类转录因子对其合成的调控作用也已阐明，但MYB类转录因子的上游调控元件还鲜有报道。ABI5是基础亮氨酸拉链家族的转录因子，作为葡萄糖和ABA信号转导途径共同的组分，在种子萌发、植物生长发育和胁迫响应中发挥重要的作用。我们前期研究表明，ABI5通过MYB转录因子调控GS的合成，并且ABI5对吲哚类和脂肪类MYB转录因子的调控方式存在差异。本项目拟进一步探明ABI5与两类MYB转录因子的互作关系，结合遗传学分析以阐明ABI5差异调控吲哚类和脂肪类GS的分子机理，鉴定MYB上游的GS调控元件，为GS的代谢调控网络提供创新性知识积累，也为通过预见性代谢工程的方法人为操纵GS组分和含量，改善芸薹属作物的品质和抗性奠定基础。

植物次生代谢物质芥子油苷具有重要的生物学功能，与十字花科作物的品质和抗性相关。拟南芥中芥子油苷的合成途径已经得到解析，其合成受到不同种R2R3-MYB类转录因子调控，但MYB转录因子的调控元件还鲜有报道。我们前期研究发现基础亮氨酸拉链家族转录因子ABI5通过MYBs参与芥子油苷合成的调控，本项目中，我们深入研究了ABI5与MYBs互作调控芥子油苷合成的机制。研究结果显示，ABI5通过结合到脂肪类MYB转录因子启动子区的CACGTG顺式元件，调节MYB的表达，从而影响脂肪类芥子油苷的生物合成；ABI5通过与吲哚类MYB的R3功能域互作参与吲哚类芥子油苷的合成调控；此外，通过烟草瞬时表达实验确定了不同种类MYBs的DNA结合域是其特异调控脂肪类和吲哚类芥子油苷合成的重要功能域，并通过IP-MS探究了MYB28可能的互作蛋白，进一步解析了芥子油苷的代谢调控网络。我们的研究揭示了芥子油苷的精细调控机制，为芥子油苷的代谢调控网络提供了创新性知识积累，在通过预见性代谢工程的方法人为操纵芥子油苷的组分和含量，改善十字花科作物的品质中具有重要的理论意义和实践价值。