Biological control and plant growth promotion properties of Streptomyces albidoflavus St-220 isolated from Salvia miltiorrhiza rhizosphere

Abstract

Root rot disease caused by <i>Fusarium oxysporum</i> is a devastating disease of <i>Salvia miltiorrhiza</i> and dramatically affected the production and quality of <i>Sa. miltiorrhiza</i>. Besides the agricultural and chemical control, biocontrol agents can be utilized as an additional solution. In the present study, an actinomycete that highly inhibited <i>F. oxysporum</i> was isolated from rhizosphere soil and identified as based on morphological and molecular characteristics. Greenhouse assay proved that the strain had significant biological control effect against <i>Sa. miltiorrhiza</i> root rot disease and growth-promoting properties on <i>Sa. miltiorrhiza</i> seedlings. To elucidate the biocontrol and plant growth-promoting properties of St-220, we employed an analysis combining genome mining and metabolites detection. Our analyses based on genome sequence and bioassays revealed that the inhibitory activity of St-220 against <i>F. oxysporum</i> was associated with the production of enzymes targeting fungal cell wall and metabolites with antifungal activities. Strain St-220 possesses phosphate solubilization activity, nitrogen fixation activity, siderophore and indole-3-acetic acid production activity <i>in vitro</i>, which may promote the growth of <i>Sa. miltiorrhiza</i> seedlings. These results suggest that <i>St. albidoflavus</i> St-220 is a promising biocontrol agent and also a biofertilizer that could be used in the production of <i>Sa. miltiorrhiza</i>.