Pathogen-activated Chaetomium globosum G3 enhances iron competition and other antagonistic mechanisms to suppress maize seedling blight causal agent Fusarium verticillioides.

Fusarium verticillioides (F. verticillioides) is a prevalent soilborne fungal pathogen that seriously threatens the production of maize (Zea mays). Species within the Chaetomium genus are recognized as potential biocontrol agents for managing plant pathogens. However, the biocontrol efficacy and underlying inhibitory mechanisms of Chaetomium species against maize seedling blight caused by F. verticillioides have yet to be comprehensively evaluated and fully elucidated. This study demonstrates that Chaetomium globosum (C. globosum) G3 reduced the disease index of F. verticillioides on maize seedlings from 81.5 % to 37.6 % and inhibited the growth of F. verticillioides by 79 %. Dual transcriptomic and metabolomic analysis revealed that when co-cultured with F. verticillioides, C. globosum G3 upregulated the iron binding pathway and enhanced the secretion of siderophore ferrioxamine. An iron supplementation experiment further indicated that C. globosum G3 inhibits F. verticillioides through more effective competition for iron. Additionally, over 60 % of the carbohydrate-active enzymes and peptidases gene expressions in C. globosum G3 were induced in response to F. verticillioides, resulting in increased activities of cellulase, chitinase, and protease, as well as the production of antibacterial compounds. Furthermore, F. verticillioides downregulated genes associated with the fumonisin biosynthetic pathway, resulting in reduced fumonisin production. These findings suggest that C. globosum holds potential as a biocontrol agent against the maize seedlings blight pathogen F. verticillioides and highlight that pathogen-activated C. globosum G3 enhances iron competition and other antagonistic mechanisms, contributing to the suppression of F. verticillioides.