Potassium Phosphite Modulated the Soil Microbiome and Enriched the Antagonistic Bacteria Streptomyces Coelicoflavus and Paenibacillus Favisporus to Inhibit the Tomato Pathogen Ralstonia Solanacearum Synergistically

Abstract

Background: Application of certain agricultural chemicals could modulate the soil microbiome and induce potential antagonistic microbes. However, the specific selective effects of agricultural chemicals on soil bacterial functions and their co-occurrences are not well understood, and no studies have verified that the enriched potential antagonistic microbes could enhance the antagonistic functions of the soil microbiome.Results: Here, the effects of potassium phosphite (KP), an environment-friendly agricultural chemical, on the soil bacterial composition, co-occurrences and antagonistic functions were determined, and the potential antagonistic bacteria against the tomato bacterial wilt pathogen Ralstonia solanacearum were isolated to test their functions and associations among these strains. Our results showed that application of KP enriched Bacillus, Paenibacillus and Streptomyces. The positive links among the OTUs belonging to these genera were increased, and positive associations between these OTUs and predicted genes related to antagonistic substance production were revealed. Two strains, Streptomyces coelicoflavus F13 and Paenibacillus favisporus Y7, were isolated, and they inhibited the growth of R. solanacearum. Genomic sequencing showed that both strains harboured streptomycin synthetic genes, and P. favisporus Y7 also contained surfactin synthetic gene cluster. Synergistic inhibition of R. solanacearum growth by P. favisporus Y7 and S. coelicoflavus F13 was observed in soil. Genome-scale metabolic modelling showed that dextrin and lactic acid were potential cross-feeding metabolites. In addition, the KP-modulated soil microbiome could suppress R. solanacearum growth. Conclusions: Our results highlight that a KP-modulated soil microbiome has considerable potential for biocontrol and indicate a new mechanism for the inhibition of R. solanacearum by KP-enriched soil bacteria.

Effects of synthetic and environmentally friendly fungicides on powdery mildew management and the phyllosphere microbiome of cucumber

“…NPA also increased the content of phytoalexin, phenolic components, flavonoids, anthocyanins and the enzymatic activity of phenylalanine ammonia-lyase (PAL) [66,67]. However, studies have reported that NPA alters the rhizosphere microbiome [68] and enriches antagonistic bacteria that inhibit plant pathogens [69]. The evidence provided in this study shows that NPA does not alter the cucumber phyllosphere microbial community, and this finding supports the specific activity of NPA as a plant defense elicitor.…”

Changes to the Bacterial Microbiome in the Rhizosphere and Root Endosphere of Persea americana (Avocado) Treated With Organic Mulch and a Silicate-Based Mulch or Phosphite, and Infested With Phytophthora cinnamomi

“…The addition of phosphite increased the abundance of soil bacteria, but the relative abundance of all the phyla was very similar across the treatments. Su et al ( 2021a ) examined the effects of phosphite on the microbiome of tomatoes and found it enhanced the abundance of Proteobacteria and Actinobacteria.…”