This study assessed the pathogenicity and toxigenic chemotypes of Fusarium species causing maize stalk rot. In addition, the ability of selected strains of Trichoderma longibrachiatum, T. koningiopsis, and T. gamsii to inhibit mycelial growth and the biosynthesis of Fusarium mycotoxins was evaluated. Pathogenicity assays indicated that F. graminearum, F. verticillioides, F. boothii, and F. subglutinans, previously characterized via morphological and molecular analyses, caused maize stalk rot symptoms with varying degrees of aggressiveness. PCR-based detection of mycotoxin biosynthetic genes revealed distinct toxigenic chemotypes among the Fusarium isolates, including fumonisin (FUM), 3-acetyl-deoxynivalenol (3-AcDON), zearalenone (ZEN), and beauvericin (BEA). After 7 days of co-culture on potato dextrose agar, all Trichoderma strains significantly inhibited the growth of Fusarium mycelia. The Fusarium pathogen inhibition rate ranged between 28.30 and 71.77%. T. longibrachiatum grew over the mycelium of the pathogen and sporulated. In rice-based co-cultured assays, Trichoderma strains inhibit FUM biosynthesis by about 74% to 92%, 3-AcDON by about 32% to 100%, ZEN by about 11% to 90%, and BEA by about 6% to 57%, depending on the pathogen–antagonist combination. The maximum reduction in mycotoxin production (100% for 3-AcDON) exceeded the maximum inhibition of mycelial growth (71.77%), suggesting that Trichoderma may repress mycotoxin biosynthesis via mechanisms independent of simple growth inhibition. These findings provide a basis for developing green biocontrol strategies for maize stalk rot.
Nan Chen (Thu,) studied this question.