Biocontrol effects of Cladophialophora spp. synthetic fungus resistant to ginger bacterial wilt

【Objective】 To evaluate the molecular phylogeny of 4 Cladophialophora spp. dark septate endophyte（ DSE）strains and the effects of their synthetic microbial community（ T4） on preventing ginger bacterial wilt, which could provide theoretical basis for the exploitation and utilization of ginger bacterial wilt biocontrol agents.【Method】The synthetic microbial community（T4） composed of 4 strains of Cladophialophora spp.were used as the test material,and the rela‐tionship of the 4 tested strains was determined by phylogenetic tree based on ITS sequence.The effect of T4 on the control of ginger bacterial wilt was tested by pot experiment.Field tests were conducted to compare the effects of chemical agent alone（CK）,biocontrol agent combined with chemical agent（treatment 1） and T4 combined with chemical agent（treat‐ment 2） on resistance indexes,growth indexes and yield of ginger.Finally,using the corresponding assay kit method,the effects of T4 on defense enzyme activity in ginger were determined. 【Result】 The 4 strains of Cladophialophora spp.formed 3 independent evolutionary clades on phylogenetic tree based on ITS sequences.Strain LC3 and the type strain of the known species Cladophialophora immunda were clustered together,strain HX2 formed a single clade,which was a newly published new species Cladophialophora guangxiense;strains LJ and MS2 were clustered together to form another independent clade,which were identified as a suspected new species Cladophialophora sp.nov.1.In potted experiment,the average plant height of ginger seedlings treated with T4 was extremely significantly increased by 58.5%compared with the Sterile water root dipping control（CK）（P＜0.01,the same below）.The control effect on ginger bacterial wilt was 51.5%after 100 d inoculated with pathogens,and the incidence rate decreased by 22.2%compared with CK.In the field test,compared with CK,the incidence rate and disease index of ginger bacterial wilt treated with treatment 2 were reduced by 25.0%and 68.6%respectively;the number of tillers,plant width and root tuber length increased by 50.4%,12.8%and 36.4%respectively;and the biological yield and economic yield increased by 50.0%and 55.6%respectively.Under pathogen stress,compared with the CK,peroxidase（POD）,superoxide dismutase（SOD）,polyphenol oxidase（PPO）,catalase （CAT）,chitinase and β-1,3-glucanase activities in ginger stalk increased by 31.2%,25.1%,10.9%,7.1%,12.2%and 32.1%respectively. 【Conclusion】 The synthetic microbial community T4 of Cladophialophora spp.has good effect on prevention and treatment of ginger bacterial wilt.The synthetic microbial community T4 of Cladophia‐lophora spp.can be used in combination with fungicides,which has a good development and utilization prospect in the biological control of ginger bacterial wilt.