研究表明，IAA(吲哚乙酸)会降低植物抗病性，而阻滞IAA信号系统却能够增强植物的抗病性。我们由此提出了"筛选IAA拮抗剂可作为发现诱导植物抗性先导化合物的新途径"的科学假设。在我们筛选诱导植物抗性海洋微生物代谢产物的过程中，发现了海洋真菌HMP-F28所产生的CPA类代谢物具有抑制植物根系生长、诱导细胞产生活性氧的活性。并且由于它们与IAA及已知IAA拮抗剂hypaphorine具有相似的结构单元，说明CPAs极有可能与hypaphorine具有相似的作用机制，即通过竞争性地抑制IAA与受体的结合而拮抗IAA。故我们推测CPAs具有通过拮抗IAA而诱导植物抗性的作用。为了验证上述假设和推论，我们拟采用OSMAC(单菌株-多产物)策略结合LC-MS追踪的手段靶向分离HMP-F28的CPA类代谢物。在此基础上，通过考察其拮抗IAA活性与诱导抗性之间的相关性来检验我们的假设和推论。

Increasing evidences showed that IAA promotes susceptibility of plants to pathogens, and that down-regulation of IAA signaling is part of the plant induced resistance response. We therefore, hypothesized that screening for IAA antagonists is a feasible way to discover leading compounds of plant resistance inducers. In the course of our screening for such metabolites from marine-derived microorganisms, a sponge-associated fungus HMP-F28 was found to produce cyclopiazonic acids (CPAs) which induced the production of reactive oxygen species in tobacco cells, and significantly inhibited the root growth in lettuce seedlings. More importantly, the CPAs share a similar substructure unit with IAA and its antagonist, hypaphorine. It implies that the CPAs may have similar antagonistic actions to hypaphorine by competitive inhibit IAA from binding to its receptors. Accordingly, we predict that, CPAs are potent IAA antagonists and can induce resistance in plants. To test our hypothesis, we propose herein a strategy for finding CPAs by OSMAC (one strain-many compounds) method and LC-MS based targeted metabolites isolation. The resulting CPAs or CPA mimics will be used for test the correlations between their IAA antagonism with induction of plant resistance. This project is significant for discovery of new plant resistance inducers and biorational pesticides for control of plant diseases.