利用MAPK级联抑制剂U0126和PD98059特异抑制MAPK信号传递途径后，使用禾谷镰刀菌侵染或脱落酸（ABA）处理玉米自交系Mo17幼苗，利用qRT-PCR分析植保素关键基因表达情况，观察MAPK级联对玉米响应禾谷镰刀菌侵染的情况。结果表明，抑制MAPK级联后，玉米叶片对禾谷镰刀菌侵染更加敏感，发病率显著提高，禾谷镰刀菌对植保素相关基因TPS6、An2、CYP71Z18、KSL5和TPS1的诱导受到抑制，且转录因子WRKY79的表达也被抑制，说明在玉米叶片中植保素的产生受MAPK级联的调控。玉米根系在MAPK级联被抑制后，ABA对这些基因表达的诱导同样受到抑制。说明MAPK级联参与植物抗病反应，在玉米叶片和根部MAPK级联可能通过调控转录因子ZmWRKY79参与对植保素代谢的调控，为玉米抗病反应机理研究提供理论依据。

Maize inbred line Mo17 was infected or treated by Fusarium graminearum or abscisic acid(ABA) after their leaves and roots were applied by U0126 and PD98059, the inhibitors of mitogen-activated protein kinase (MAPK) cascade. The key genes' expression of maize phytolaexin biosynthesis was analyzed with qRT-PCR, and F. graminearum development and infection rate in maize leaves were evaluated. The inhibition of MAPK cascade significantly increased the F. graminearum susceptibility of maize and resulted in higher disease incidence, indicating that MAPK cascade positively correlated with the disease resistance. Further, the expression of maize phytoalexin biosynthetic genes was induced by pathogen infection, suggesting that phytoalexin metabolism is related with MAPK cascade in maize leaves. In addition, when MAPK cascade in roots was inhibited by U0126 and PD98059, the induction effect of ABA on phytoalexin related genes was decreased significantly, indicating that MAPK cascade is involved in the phytoalexin accumulation in maize roots. The expression level of ZmWRKY79, a transcription factor of maize terpenoid phytoalexins, was also compromised after MAPK cascade was inhibited. So, MAPK cascade positively regulates maize disease defense response, which is realized through regulating the expression of transcription factor ZmWRKY79. The result would provide the cue for clarification of MAPK cascade function in maize.

国家自然科学基金（31671708）