Abstract: 【Objective】Systematic studies on the effects of MAPK (Mitogen activated protein kinase) signal transduction pathway on the growth, development and pathogenicity of Setosphaeria turcica will not only help us to understand the molecular mechanism of pathogen-host interaction, but also benefit the effective control of the diseases caused by S. turcica.【Method】U0126, the specific MEK inhibitor, was used to treat S. turcica before observing the conidial germination, appressorium production and pathogenicity of the pathogen.【Result】There was no significant effect of U0126 on the pathogen's colony morphology and mycelium growth. After treatment with U0126, the mycelium and conidia were normal, but the conidial germination, appressorium production and pathogenicity to susceptible corn leaves were significantly inhibited. Under the definite concentration scope, U0126 increased the inhibition degree to conidial germination and appressorium production with the increase of U0126 concentration, but the inhibition degree decreased with elongation of the treatment time.【Conclusion】The conidial germination, appressorium production and pathogenecity to susceptive corn leaves are regulated by the MAPK pathway inhibited by U0126.

Key words: Setosphaeria turcica, MAPK, U0126, Conidial germination, Appressorium production, Pathogenicity