Growth promotion effects of Bacillus amyloliquefaciens on potato under water deficit by combining microbiome and metabolome

【Objective】 This paper investigated the effects of Bacillus amyloliquefaciens B9601-Y2 inoculation on root growth metabolism and rhizosphere bacterial structural diversity of potato under water deficit,so as to provide a theoretical basis for the interaction between microorganisms and plants and the induction of drought tolerance in plants.【Method】 A strain of B. amyloliquefaciens B9601-Y2 and a water-deficit sensitive potato variety Dianshu 1418 were used as materials. Four treatment groups were set:BD:inoculation treatment under water deficit condition with soil relative humidity(45± 5)%; BCK:inoculation treatment under normal water supply condition with soil relative humidity(75±5)%; control (CK):normal water supply condition without inoculation treatment;D:water deficit condition without inoculation treatment (blank control). The colonization of strains in each treatment was measured. Extensive targeted metabolomics technology and Illumina NovaSeq sequencing technology were used to analyze the diversity and relative abundance of potato root metabolites and soil bacteria.【Result】 B9601-Y2 could colonize potato roots under water deficit condition,with a colonization rate of 65.71%. Microbial treatment had extremely significant effects on potato root activity and root-shoot ratio(P< 0.01,the same below). According to rhizosphere bacterial diversity,a total of 7538 operational taxonomic unit(OTU) were obtained by OTU clustering. BD increased the relative abundance of Nocardioides and Marmoricola. The differential metabolites in roots were mainly concentrated in amino acid biosynthesis pathway. Among them,5 amino acid differential metabolites were affected by different water treatments,and 3 amino acid differential metabolites were affected by different bacterial inoculation treatments. The combined analysis of microbiome and metabolome showed that Iamia was extremely significantly positively correlated with N-formyl-L-methionine and L-γ-glutamine-L-leucine in BD. In BCK and BD treatments, Pseudonocardia, Marmoricola and Nocardioides were extremely significantly positively correlated with L-methionine and L-proline.【Conclusion】 B. amyloliquefaciens B9601-Y2 can be colonized in potato roots under water deficit condition,which can increase root activity and root-shoot ratio,change the structure and relative abundance of bacteria in the rhizosphere. The close interaction between dominant bacteria and differential metabolites of amino acids can promote potato growth and improve its tolerance to drought.