| Magnaporthe grisea is best known for the causal agent of rice blast , the most destructive disease of rice worldwide and depends on appressorium formation for successfully penetrating host leaf surface. According to recent researches, intracellular signalling pathway systems involved in appressorium differentiation is related with cAMP pathway and MAP pathway. In this research, 21 bacteria strains and Chaetomium cupreum strains were assayed for their antagonism to appressorium formation in M.grisea. Main results were presented as follows:Among 21 bacteria strains, 3 strains induced conidia of the pathogen to produce swollen cells (abnormal appressorium) on the sites of the appressorium differentation. 4 strains could inhibit conidium germination, 5 strains made the pathogen grow vegetably and 9 strains inhibited its tube growth.M.grisea produce several swollen cells on the sites of the appressorium differentation and lost the ability to infect onion epidermis treated with the culture supernatant of h23 strain. Treatment of barley leaves with h23 strain resulted in a significant reduction by 70.4% in the number of lesions in vitro-, The antagonistic substance produced by h23 strain was precipitated with 60% saturation ammomium sulfate solution and was stable under organic solvent, heat, and proteinase treatment, it was speculated that the antagonistic substance in h23 strain was low molecular weight and comprised certain amindo (amindos).Chaetomium cupreum strains effectively inhibited conidium germination, tube growth and appressorium formation in grisea. Evidence from cAMP and IB MX tests showed that Chaetomium cupreum strains disturbing appressorium development might be through inhibition of Pmkl kinase.
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