Potential Of Biological Control Of Strain Chaetomium Globosum W7 And It’s Secondary Metabolites

Chaetomium globosum has a huge potential to developed as a plant disease biological control agent.It can improve the ability of disease control,and it also can improve the yields of crops.In addition,discoveries about new secondary metabolites of Chaetomium globosum which generally have good biological activities were continuously reported.Therefore,study on potential of biological control and secondary metabolites of Chaetomium globosum have important theoretical meanings and application prospects.Here we performed anti-fungal bioassay of seven endophytic fungi isolated from Ginkgo biloba.One Chaetomium globosum(strain W7)was activated against all kinds of the selected plant pathogens,Rhizoctonia solani,Fusarium graminearum,Sclerotinia sclerotiorum,Phytophthora capsici,by using the mycelial growth inhibition method.Specially,strain W7 showed a strong inhibitory activity towards S.sclerotiorum,the inhibit zone in the dual-culture plate was evident.The inhibit effect of 100%fermentation broth on germination of sclerotium was 87.1%.The effect on mycelia respiration activities of 10%fermentation broth was reduced 67.83%than blank control after 9 hours’ treatment.The protective efficacy of 50%fermentation broth was 42.21%which was comparable to the commonly used fungicide carbendazim at the concentration of 125 μg/mL.The 10%fermentation broth can promote the growth of rape seeds.Furthermore,the inhibitory activities of mycelial growth was not reduced under the heating on 60 ℃ ultraviolet radiation and stored at 4 ℃ for 29 days,but it significantly reduced after 100 ℃ heating.Among the different organic phases from the fermentation broth of C.globosum(strain W7),we found that the crude extracting of dichloromethane phase had a better activity,it’s inhibition efficacy of mycelial growth in vitro was 82.1%under the concentration of 20 pg/mL.At the same time,seven known compounds Ravipin(compound 1),cheatoglobosin C(compound 2),B(compound 3),D(compound 4),E(compound 5),Vb(compound 6),A(compound 7)were obtained from the dichloromethane phase.The crystal structures of flavipin and chaetoglobosin D were reported for the first time.Cheatoglobosin B,D can inhibit the growth of Rhizoctonia solani and Botrytis cinerea with EC50 values are all under 0.5 μg/mL,cheatoglobosin A can inhibit the growth of Botrytis cinerea,Phytophthora capsici,Fusarium graminearum,Alternaria solani and Magnaporthe grisea with EC50 values are all under 0.4 μg/mL.Becides,under the concentration of 500 μg/mL,the protective efficacy of cheatoglobosin D,A(42.52%、44.94%)were all comparable to the positive control carbendazim in a concentration of 125 μg/mL(42.52%).We preliminary studied the antifungal mechanism of the secondary metabolitite of C.globosum named flavipin for S.sclerotiorum.The result showed that flavipin can reduce the respiratory rate of hyphae of the pathogen,when the processing time was up to 12 hours,the respiratory rate was 68.08%lower than blank control.It can also inhibit the activity of of mitochondrial succinate dehydrogenase(SDH)of S.Sclerotiorum,the value of IC50 was 33.02 μg/mL.Besides,we tested the content changes of three compounds in the fermentation broth of strain W7 after heating on 60 ℃ 100 ℃ and ultraviolet radiation,respectively.The result showed that cheatoglobosin B,D,A were all sensitive for heating,as the extension of heating time,the content of cheatoglobosin B,D were slightly increased,while the content of cheatoglobosin A was significantly declined.Relatively,these there compounds were less sensitive for ultraviolet radiation.After the ultraviolet radiation,the content of cheatoglobosin A was increased slightly,while no significant changes were happened in the content of cheatoglobosin B and cheatoglobosin D.