Abstract:In order to evaluate the potential application of Streptomyces padanus JAU4234 in the biological control for plant diseases, the action mechanism of DZP-8 (an active product isolated and purified from the fermentation broth of S.padanus JAU4234) against Rhizoctonia solani was investigated in virtue of the mycelium growth rate quantification, enzyme activity determination, together with the protein analysis by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). It was found that the DZP-8 had a strong antagonistic action on that of R.solani hyphae, and the EC50 value was 1.55 μg/mL. With the increase of DZP-8 concentration, the activities of the carboxy methyl cellulose enzyme (Cx), polygalacturonase (PG) and pectin methyl galacturonase (PMG) of R.solani were all decreased. When the DZP-8 concentration was 4.67 μg/mL, the activities of the above three cell wall degrading enzymes were 6.76, 20.97 and 21.74 U/mg, respectively, which were all significantly lower than those of control group. Furthermore, soluble mycelium proteins only displayed a pattern of 8 protein bands under 4.67 μg/mL of DZP-8, in which the number of protein bands showed a significant difference to the control group. According to the above results, it could be concluded that the significantly inhibitory effect of DZP-8 on R.solani was due to the integrative action of DZP-8 on the mycelial growth, pathogenic factor expression and protein synthesis.