Trichoderma ear rot: Insights into grain quality degradation, trichothecene risk and metabolic alterations in maize

Abstract

Maize is increasingly affected by ear rot diseases that compromise grain quality and yield. Although Trichoderma is commonly used as a biocontrol agent, this study reports the pathogenic strains of Trichoderma from Karnataka, India. Pathogenic strains were identified as Trichoderma asperellum and T. atroviride through morphological and molecular characterisation. Pathogenicity assays yielded disease severity scores ranging from 80.00 % to 92.00 %. Notably, T. asperellum showed rapid green conidiation and dense colonization, while T. atroviride exhibited slow sporulation. Amplification of the TRI5 gene in T. asperellum indicated a potential for trichothecene production, posing additional risks to food and feed safety. Trichothecene contamination in maize thus poses significant health risks to animals and humans by impairing immunity, growth and gut function, highlighting the need for strict feed monitoring and control. Infected kernels showed significant starch degradation: T. atroviride reduced total starch to 38.12 % and amylose to 7.77 %, while T. asperellum reduced them to 44.94 % and 9.11 %, respectively, compared to 70.10 % and 11.43 % in healthy kernels. Germination assays revealed reduced seedling vigor, with T. atroviride more strongly affecting germination rate and T. asperellum reducing root growth and biomass. LC-MS/MS-based metabolomics identified 572 compounds, including 92 unique to infected kernels, with major disruptions in amino acid, vitamin B6, glutathione, and sulfur metabolism, especially in samples with visible mycelial mats. These findings highlight the dual role of Trichoderma spp. as both biocontrol agents and potential pathogens, underscoring the importance of careful strain selection and environmental monitoring in their use in agriculture.