The Identification Of Wheat Pathogen And Primary Study On Its Antifungal Agent

It was reported that Fusarium lateritium, which had various hosts, could infectdifferent trees、bushes and cash crops et al., resulted in wilt、canker and othersymptoms. It also infected certain seedlings sometimes, brought serious destroy. So itis extreme significant to screen microorganism of high antagonistic activity againstFusarium lateritium and turn it into antifungal agent to control the disease and losscaused by Fusarium lateritium and protect environment. Though Fusarium lateritiumcan infect various seedlings, vegetables and melons, its pathegenicity on wheat waslittle reported.A Fusarium strain was identified to be Fusarium lateritium by morphologicaland molecular techniques. After that, we used the water planting and potted wheat toinvestigate its pathegenicity on wheat, the results showed that Fusarium lateritiumcould infect wheat (Zhengmai9023and Yumai49) under suitable surroundings.In order to obtain microorganism of obvious antagonistic activity againstFusarium lateritium, we did some studies and got some results as follows: About104bacterial strains were isolated from soils obtained from a maize field and wheat fieldsuppressive to many plant pathogens, and5of them had obvious antifungal activityagainst Fusarium lateritium, which were named BS-01、BS-02、BS-03、BS-KU、BS-HOT1respectively. According to the morphological and physiologicalcharacteristics and phylogenetic analysis of the16S rDNA sequence, they wereidentified as Bacillus subtilis. In addition, It was confirmed that Fusarium lateritiumcould be inhibited effectively by the5strains fermentation filtrate, and the inhibitionefficiency of BS-02was the best. Under the help of optical microscopy, we also foundthat Bacillus subtilis BS-02could produce the antifungal materials to inhibitFusarium lateritium.In order to heighten the antifungal effect, we used strain BS-02as the startingstrain to conduct the single factor experiments and orthogonal experiment, and theoptimum fermentation conditions were determined as follows:12h germ,1%saccharose,1%yeast extract,0.5%NaCl, initial pH5.0,5%inoculum,50mL/250mL,210r/min,31℃,48h. The results of relevant experiments indicated that different treatment methods ofstrain BS-02fermentation broth had an influence on the antifungal activity. Thehighest effective one was the original fermentation broth treated by Micro-membranefilters(0.22μm), and the inhibition efficiency of that being sterilized under115℃,30min was about70%of the former one. As previously stated, we could draw theconclusion that the strain BS-02original fermentation broth, which was obtainedunder the mentioned-above optimal conditions and sterilized by Micro-membranefilters (0.22μm), had optimal antagonistic activity, and could be used as antifungalagent against Fusarium lateritium.