| As the main soilborne diseases of potato,potato fusarium wilt and black scurf of potato are self-evident.Generally,chemical agents are used to control it,but frequent use of chemical agents is easy to cause harm to the environment,and cause the pathogen to produce a certain degree of resistance.Biological control has attracted more and more attention due to its pollution-free and environment-friendly characteristics.However,the use of single biocontrol bacteria has some problems,such as unstable colonization,and the control effect is sometimes not ideal.The combined use of a variety of microorganisms can stabilize colonization,enrich microbial community structure,and significantly improve the control effect of plant diseases,which is often better than the control effect of a single biocontrol bacteria.In this study,coculture broth of Trichoderma asperellum PT-29 and Bacillus subtilis S-16 in different medium conditions was used to control potato fusarium wilt and black scurf of potato,and to explore the difference in control efficiency between Trichoderma asperellum PT-29 and Bacillus subtilis S-16 as well as the influence of biocontrol bacteria on each other’s growth under coculture conditions.Through co-culture of Trichoderma asperellum PT-29 and Bacillus subtilis S-16,the biocontrol mechanism of plant defense enzyme activity changes and different metabolites in fermentation broth were analyzed,and the following results were obtained:1.The co-culture of Trichoderma asperellum PT-29 and Bacillus subtilis S-16 showed significant inhibitory effects on Fusarium oxysporum and Rhizoctonia solani.In the fermentation broth prepared by PDB,the inhibition rate of co-culture broth B1T1 on Fusarium oxysporum and Rhizoctonia solani was 58.05% and 54.40%,respectively.They were significantly higher than that of monoculture fermentation solution B and T.The results were the same in the fermentation broth prepared by PB,and the inhibition rates of co-culture broth B1T1 against Fusarium oxysporum and Rhizoctonia solani.were significantly higher than those of single culture broth B and single culture broth T.(2)When the co-culture ratio of Trichoderma asperellum PT-29 and Bacillus subtilis S-16 was 1:1,Trichoderma asperellum PT-29 promoted the growth of Bacillus subtilis S-16.In either the fermentation solution prepared by PDB or the fermentation solution prepared by PB,when the co-culture ratio of the two was 1 to 1,the amount of bacteria in S-16 was significantly more than that in monoculture B,that is,in S-16.However,when Trichoderma asperellum PT-29 was co-cultured with Bacillus subtilis S-16,the dry weight of mycelia in PT-29 was significantly lower than that in monculture-medium B,that is,monculture-Pt-29,no matter what proportion was inoculated.(3)The co-culture broth of Trichoderma asperellum PT-29 and Bacillus subtilis S-16 had better biocontrol effect on potato fusarium wilt and potato naevus.In both the fermentation broth prepared by PDB and the fermentation broth prepared by PB,co-culture fermentation broth B1T1 has the best control effect on potato fusarium wilt and potato nevus disease,which is better than that of single culture fermentation broth B and single culture fermentation broth T,but the fermentation broth prepared by PDB has better control effect on these two diseases.(4)The results showed that coculture of Trichoderma asperellum PT-29 and Bacillus subtilis S-16 could induce the improvement of potato disease resistance,and the average activities of four kinds of defense enzymes in co-culture fermentation broth B1T1 were higher than those in single culture fermentation broth,The peak values were 2101.8,75.33,39231.5 and 57.09 U/g,respectively.(5)Through the non-targeted metabolomics analysis in monoculture and co-culture mode,mainly amino acids,esters,organic acids and vitamins.The results of differential metabolite screening showed that the total number of metabolites with significant differences in B.V.CC＿positive ions was 232,96 were significantly up-regulated and 136 were significantly down-regulated.The total number of metabolites with significant differences in T.V.CN positive ions was 201,114 were significantly up-regulated,and 87 were significantly down-regulated.The total number of metabolites with significant positive ion difference in B1T1.vs.CK was 210,115 were significantly up-regulated,and95 were significantly down-regulated.The total number of metabolites with significant difference of negative ions was 169,59 were significantly up-regulated,and 110 were significantly down-regulated.The total number of metabolites with significant differences in the negative ions of T.V.CN was 149,54 were significantly up-regulated,and 95 were significantly down-regulated.The total number of metabolites with significant differences in negative ions of B1T1.vs.CK was 146,of which 55 were significantly up-regulated and91 were significantly down-regulated. |
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