Pathophysiology And Biological Control Of Maize Curvularia Leaf Spot

In this study,3 fungu were isolated from leaves of maizes, named zsy-01, zsy-02 and zsy-03. zsy-01 was identified as Curvularia lunata by observation of colony morphology and analysis of ITS1-5.8S-ITS2 rDNA sequence. The fungi with laccase activity was detected using syringaldazine, guaiacol and ABTS.Health maize leaves were inoculated with Curvularia lunata. It was found that Curvularia could produce cell wall-degrading enzymes (CWDE) (PG, PMG, and Cx) and laccase, either in vivo or in vitro. CWDEs producted in-order, firstly, PG and PMG were produced, then Cx appear along with. Laccase consumption of phenols, and it could accelerate pathogen-disseminated. The quantity of CWDEs are lower In vitro than that of in vivo The enzyme activities of CWDEs in resistant cultivar were lower than those in susceptible one, but the peak in resistant variety showed earlier.The changes of defensive enzyme activities and phenolics were studied in maize leaves infected by Curvularia lunata within one week after inoculation. The results are as follows: the changes of phenolics were correlated with pathogen infection. Phenolics in both Resistant varieties and Susceptible varieties accumulated after the inoculation with Curvularia lunata. Furthermore, the accumulation of phenolics in Resistant varieties was not only faster, but also greater than in Susceptible varieties. The activity of Pnylalanine Ammonia-lyase (PAL) increased in both resistant and susceptible cultivars after inoculation. The activity of PAL in resistant cultivar increased faster and greater than that in susceptible one. POD activity increased rapidly in the early and middle infection stages, but decreased a little in the late infection stage in both resistant and susceptible cultivars.In this paper, the inhibiting effect of Bacillus subtilis culture, filtered supernatant, and deactivation on the growth of stains zsy-01, zsy-02 and zsy-03 was studied. The results showed that Bacillus subtilis culture inhibited hypha of zsy-01, zsy-02 and zsy-03 from growing. At the concentration of 105 CFU/mL, the inhabition of Bacillus subtilis culture on zsy-01, zsy-02 and zsy-03 were all 100%. When the concentration was 104 CFU/mL, the inhibiting effect decreased evidently. The inhibition of filtered supernatant on zsy-01, zsy-02 and zsy-03, were all above 50%. The inhibiting effect of the deactivation was lower than that of culture or filtered supernatant. The inhibition on zsy-01, zsy-02 and zsy-03 was 69.2%,53.4% and 46.9%, respectively.The antagonistic action of the non-volatile metabolites and volatile metabolites of Trichoderma viride with zsy-01, zsy-02 and zsy-03 was researched. We drew the conclusion that the non-volatile metabolites and volatile metabolites of Trichoderma viride had inhibition effect to three kinds of pathogens.