Cysteine Inhibits the Growth of Fusarium oxysporum and Promotes T-2 Toxin Synthesis through the Gtr/Tap42 Pathway

F. oxysporum and its T-2 contamination of food not only leads to food wastage but also poses a major food safety challenge to humans. The growth and T-2 production characteristics of F. oxysporum in high-protein substrates are considerably different from those in grains. Here, we show that the abundant free amino acids in a protein-rich food matrix are a key regulatory factor for the growth of, and toxin production by, F. oxysporum. Cysteine has the most pronounced effect on inhibiting mycelial growth and promoting T-2 synthesis through the TORC1 pathway. This implies that consumers tend to overlook T-2 contamination due to the poor growth of F. oxysporum in food rich in protein and amino acids, especially cysteine. Therefore, particular attention should be paid to the protection of those products.