Antifungal Activity of Essential Oil Compounds (Geraniol and Citral) and Inhibitory Mechanisms on Grain Pathogens (Aspergillus flavus and Aspergillus ochraceus)

The grain contamination byAspergillusspp. has been a serious issue. This study exhibited the excellent antifungal effects of the essential oil compounds (EOCs) geraniol and citral against common grain pathogens (A. flavusandA. ochraceus) in vitro and in situ. The inhibitory mechanisms were also evaluated from the perspective of cell membrane permeability, reactive oxygen species (ROS) generation, andAspergillusspp. growth-related gene expression. Meanwhile, the combined effects of EOCs in the vapor phase and modified atmosphere packaging (MAP) were examined to find an alternative preservation method for controllingAspergillusspp. The results indicated that citral exhibited the antifungal activity mainly by downregulating the sporulation- and growth-related genes for both pathogens. Geraniol displayed inhibitory effectiveness againstA. flavuspredominantly by inducing the intracellular ROS accumulation and showed toxicity againstA. ochraceusprincipally by changing cell membrane permeability. Furthermore, the synthetic effects of EOCs and MAP (75% CO2and 25% N2) induced better grain quality than the current commercial fumigant AlP. These findings reveal that EOCs have potential to be a novel grain preservative for further application.Keywords:antifungal activity;geraniol;citral;Aspergillus;relative electric conductivity;reactive oxygen species;gene expression;modified atmosphere packaging