芥子油苷代谢参与青花菜对甘蓝链格孢菌响应的作用机制

The black spot disease on Brassicaceae crops caused by Alternaria brassicicola, an important saprophytic fungal pathogen, is of worldwide economic importance and the most severe disease in Brassica oleracea var. italica. Cruciferous plants produce a wide variety of glucosinolates as a protection against biotrophic pathogens and involving in MAPK-triggered immune responses in planta. However, very little is known about the importance of individual glucosinolates in response to necrotrophic fungi. An altered profile that the production of aliphatic glucosinolates were reduced and the production of indole glucosinolates especially 1-methoxyindol-3-ylmethylglucosinolate was induced was observed in the broccoli florets infected by A. brassicicola. The response pattern was distinct with that the induction of 4-methoxyindol-3-ylmethylglucosinolate in Arabidopsis incubated with biotrophic fungi. In this program, in order to study the mechanism of glucosinolates in response to A.brassisicola, the glucosinolates-derived products in broccoli with or without A.brassisicola infection are identified basing on metabonomics. The genes involved in the glucosinolate metabolism and regulation network are evaluated basing on genomics and comparative genomics. Moreover, these glucosinolates and glucosinolate-derived products response to the pathogen are extracted from various broccoli lines or Arabidopsis glucosinolate mutants and used for examine the activities of inhibit growth and development of A.brassicicola isolates and production of pathogenicity factors in vitro. On the other hand, combining with purified glucosinolates and glucosinolate-derived products feeding experiments, the experiments with or without artificial inoculation with A. brassicicola were conducted in the pure lines with various glucosinolate patterns to reveal the roles of glucosinolate metabolism in pathogenicity and innate immune responses during the interaction between broccoli and A.brassisicola. The Alternaria brassicicola-Brassica oleracea pathosystem developed in this research will provide a good study system for the interaction between Brassicaceae and necrotrophic fungi. The implement of this study allows us to further reveal the roles and mechanism of gluosinolate metabolism in plant defense under biotic stress.

黑斑病是十字花科作物中由腐生型真菌甘蓝链格孢菌引起的重要病害,也是青花菜中危害最严重的病害；芥子油苷则是十字花科植物中重要的防卫化学物质。本项目拟以青花菜和甘蓝链格孢菌相容的植病系统为对象,研究青花菜中芥子油苷的代谢途径响应甘蓝链格孢菌的分子机制；基于代谢组学挖掘在青花菜与甘蓝链格孢菌互作中新的芥子油苷代谢产物；以芥子油苷组分特异的青花菜为材料，通过分离纯化不同组分的芥子油苷及代谢产物，外源和内源相结合，研究其在青花菜和病原菌互作中的生物学功能和在植物免疫中的作用。本项目为研究十字花科植物与死体营养型真菌的互作提供了良好的试验系统，有助于揭示芥子油苷代谢途径在植物与生物性胁迫互作中的生物学功能与作用机理，并在作物改良上有很大应用前景。

十字花科植物产生芥子油苷防卫活体病原菌并参与了MAPK调控的植物免疫。黑斑病是十字花科作物中由腐生型真菌甘蓝链格孢菌引起的重要病害,也是青花菜中危害最严重的病害。在本项目中，我们发现吲哚族芥子油苷受到甘蓝链格孢菌的诱导，而脂肪族相反，基因表达分析表明，吲哚族芥子油苷合成与调控相关基因被激活，而脂肪族受到抑制。通过吲哚族芥子油苷合成抑制剂以及外源处理试验证实青花菜中吲哚族芥子油苷代谢参与了对甘蓝链格孢菌的防卫，而且吲哚族芥子油苷代谢产物IAN和IMA不仅可以抑制病原菌的生长，还抑制部分致病基因bPro1, AbSte12 和 AbNIK1的表达，从而实现了对甘蓝链格孢菌的防卫。