| Wheat sharp eyespot is a wheat disease caused by Ceratobasidium cereale,which is one of the important factors restricting the high and stable yield of wheat.At present,using chemical agents to control wheat sharp eyespot is the main measure.However,due to the overuse of chemical fungicides,pathogenic fungus develop drug resistance,which also causes serious harm to the environment,so it is necessary to carry out biological control and other studies.Through the isolation and screening of soil bacteria,a strain of H-BX7 which has good biocontrol effect on wheat sheath blight was obtained,and its whole genome was sequenced and identified.The main results are as follows:(1)According to physiological and biochemical characteristics,16 S r DNA,rec A sequence alignment and whole genome sequencing results,H-BX7 is a member of Burkholderia.The classification system of strain H-BX7 was determined.(2)According to the plate inhibition test,the inhibition rate of biocontrol bacterium H-BX was 67.47%,and the mycelia of pathogenic bacteria had significant changes compared with normal mycelia,with mycelia distorted,branching increased and branching shorter.Through the bacteriostatic spectrum experiment,the antibacterial activity of H-BX7 was a broad spectrum.The best medium for volatile substance production was NA medium,and the bacteriostatic rate was 78.57%.After root irrigation with H-BX7,the fresh weight,root length,leaf length and dry weight of wheat increased by 5.16%,7.92%,7.66% and 3.84%respectively.The potted control effect test showed that the highest control effect was 47.92%after H-BX7 treatment.Therefore,H-BX7 is a bacterium with good antifungal and plant growth promotion effects.(3)By Prometh ION sequencing platform,the complete genome of H-BX7 contains 3Contigs of 78,725,833 bp with 66.53% GC content and 6994 CDS.COG,GO and KEGG database annotation showed that strain H-BX7 was particularly active in transcription and active in carbohydrate and amino acid metabolism.An online prediction by anti SMASH found that H-BX7 was 94% similar to the gene cluster that produces the antifungal polypeptide Occidiofungin A.In this study,the genomic data of H-BX7 were obtained,and the candidate genes related to synthesis and metabolism of H-BX7 and candidate antimicrobial metabolites were analyzed.These results provided a strong support for further elucidating the biological control function of this bacterium.(4)Pan-genome analysis of 24 Burkholderia strains was performed using BPGA software:there were 2718 core genes,258 unique genes of H-BX7 and 3538 non-essential genes,and the pangenome was open.The genomic collinearity analysis of 5 Burkholderia strains was carried out by Mauve software.The collinearity level between the strains was not high,and there were many insertions,deletions and inversions,which proved that Burkholderia could better adapt to the living environment by expanding genes to add new functions under longterm selection pressure.In conclusion,strain H-BX7 has good biocontrol and plant growth promotion effects.The results showed that H-BX7 exhibited extensive antibacterial activity,and the main mechanism of antagonism and growth promoting effect of H-BX7 was clarified from the level of genome and metabolites,providing a biological control method for Wheat sharp eyespot. |
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