Insights into the antifungal and anti-aflatoxin B1 mechanisms of carvone on Aspergillus flavus

Aspergillus flavus (A. flavus) and the carcinogen it produces, aflatoxin B1 (AFB1), often contaminate essential fat- containing crops and cereals, posing a significant risk to food safety and human health, and resulting in substantial economic losses. The development of green, safe, and environmentally friendly chemical fumigants for controlling A. flavus and AFB1 contamination is urgently needed. The effects and mechanisms of the natural compound carvone on A. flavus growth and AFB1 biosynthesis were therefore investigated. Carvone efficiently inhibited A. flavus growth, spore formation, and AFB1 production. The minimum inhibitory concentration (MIC) was 0.8 mu L/mL. RNA-seq analysis showed that carvone inhibited spore formation by suppressing the transcription of spore development-related genes, including fluG, flbA, flbD, brlA, abaA, con6, con10, rodA, rodB, and dit2. Physiological and biochemical parameters showed that carvone disrupted the integrity of the cell wall and membrane, induced reactive oxygen species (ROS) accumulation, caused DNA damage, triggered cell autophagy, reduced ATP levels, which ultimately led to cell death. RNA-seq analysis confirmed these results, which found that genes related to chitin and ergosterol synthesis, and DNA replication were downregulated, and genes involved in antioxidants and cell autophagy were upregulated. In addition, carvone downregulated several transcription factors (CreA, SrrA, NsdD, and Crz1) and 11 AFB1 cluster genes, which inhibited AFB1 production. Together, the results provided new insights into the antifungal and anti-AFB1 mechanisms of carvone, as well as providing theoretical support for the development of new fumigants to control A. flavus and AFB1 contamination.