Analyzing Composition Of Bacterial Community And Screening Of Biocontrol Bacteria Strains In Maize Rhizosphere

Maize is one the most important crops in the world.As the main constraint in maize production,maize diseases caused the reduction in production by more than 10% every year.Rhizosphere soil microbes have a close relationship with plant growth.The biocontrol technique of plant disease based on microbiome will play a key role in plant disease control and have a wide application prospect.To clarify bacterial composition of maize rhizosphere and to screen biocontrol resources for maize diseases,a total of 1584 bacteria strains were isolated from maize rhizosphere by culture-dependent method.The bacteria were classified into Proteobacteria,Actinobacteria,Firmicutes and Bacteroidetes,of which Proteobacteria were the dominant groups.At genus level,Pseudomonas were the most abundant groups.A total of 162 bacteria strains with antagonism against Setosphearia turcica were selected through plate confrontation method and Strain D3 had the strongest antifungal effect.Moreover,strain D3 was identified as Bacillus amyloliquefaciens by morphological and molecular methods.Strain D3 had broad-spectrum antifungal effect on plant fungal pathogens including S.turcica,Colletotrichum graminicola,Fusarium avenaceum and Curvularia lunata.Using the specific primers of lipopeptide gene,the related genes were amplified by PCR in strain D3.Additionally,cell-free filtrate and the crude extract of lipopeptide from strain D3 had identically biocontrol effect on pathogen.In conclusion,Strain D3 can be used as a new biocontrol microorganism against maize fungal diseases.Using metagenomics to analysis the composition of soil microbes community in China six maize area,?-diversity results showed that the distribution of microbial abundance was not uniform among different provinces.?-diversity analysis demonstrated that geographic location had a significant effect on soil microbes.We have detected a core microbiome composed of 141 genera,and observed soil pH was the biggest factor affecting the dominant microbiome.COG and GO database were used to predict the gene function of dominant microbiome,the most number of gene related to aminoacid transport and metabolism,followed by general function prediction only,cell wall/membrane/envolope biolgenesis,carbohydrate transport and metabolism.Next,we isolated 21797 bacteria strains and 2810 fungal strains from soil samples.Constructing a cultural microbe repository.A total of 539 bacteria strains with antagonism against soil-borne diseases of maize were selected.Biocontrol strains predominantly come from Proteobacteria and Firmicutes.At genus level,Bacillus and Pseudomonas were dominant bacteria,respectively.In this study,we combined traditional culturable method and modern genomic sequencing technology to analysis the composition of bacteria in maize rhizosphere,obtained plenty of biocontrol microbe resources,which would lay the foundation for biocontrol of maize diseases.