Biochemical defense responses of maize to Fusarium ear rot: Insights into resistance and eco-friendly management

Abstract

Maize ear rot, primarily caused by Fusarium verticillioides represents a major threat to yield, grain quality, and food safety due to fumonisin contamination. PCR for ITS region confirmed the predominance of F. verticillioides (~800 bp amplicon). Laboratory assays, greenhouse and field trials demonstrated that Zinc oxide nanoparticles (ZnO-NPs), citric acid, moringa aqueous seed extract, propolis ethanolic extract, and black pepper aqueous extract significantly inhibited F. verticillioides growth with ZnO-NPs showing the strongest efficacy. Under both natural and artificial inoculation, these treatments reduced disease incidence and severity, enhanced defense-related enzymes, Polyphenol oxidase (PPO) and Catalase (CAT) and promoted phenolic accumulation. Field trials over two consecutive seasons corroborated these findings, where ZnO-NPs and propolis ethanolic extract consistently provided the highest levels of disease suppression, improved nutritional quality (oil and protein preservation), and significantly reduced fumonisin contamination. Collectively, these results demonstrate that natural elicitors, particularly propolis ethanolic extract and ZnO-NPs, offer sustainable and eco-friendly alternatives to conventional fungicides for managing maize ear rot and mitigating mycotoxin accumulation.