A novel endophytic fungus Fusarium oxysporum G-07 exhibits antagonism against Rhizoctonia solani and promotes growth in Scutellaria baicalensis.

In China, the continuous cropping leads to frequent outbreaks of root rot caused by the pathogen Rhizoctonia solani and soil fertility degradation, which are the primary causes of reduced yield and quality of the famous medicinal/edible plant, Scutellaria baicalensis. In the present study, a novel endophytic fungus, Fusarium oxysporum G-07, isolated from S. baicalensis, was found to exhibit antagonistic activity against R. solani and demonstrate multiple plant growth-promoting (PGP) characteristics. The crude extracts of F. oxysporum G-07 could significantly inhibit the growth of R. solani and promote the rooting of S. baicalensis adventitious buds, which was likely attributed to the presence of four host-specific metabolites (baicalin, baicalein, wogonoside, and wogonin), nine potential antimicrobial compounds (p-coumaric acid, daidzein, vanillin, acetophenone, sorbic acid, isoquinoline, eriodictyol, linoleic acid, and ferulic acid), and three phytohormone-like components (indoleacetic acid, indole-3-acetaldehyde, and salicylic acid). Inoculation with F. oxysporum G-07 could effectively control root rot in S. baicalensis seedlings caused by R. solani, while also significantly promoting the growth and development of the roots and aboveground parts. F. oxysporum G-07 could successfully colonize the host roots and was essentially recognized as a biosafety strain. Furthermore, F. oxysporum G-07 was able to alleviate the secondary metabolic defense response induced by R. solani infection in S. baicalensis seedlings, and upregulate the expression of auxin-responsive gene. Overall, F. oxysporum G-07 is a promising microbe with the potential to control root rot and promote the growth and development of S. baicalensis.