Mitochondrial dysfunction via oxidative stress and calcium imbalance mediates antifungal activity of calcium propionate against Trichothecium roseum.

Trichothecium roseum is an important postharvest pathogenic fungus, which can cause postharvest disease of diverse fruit. In addition to causing decay and quality deterioration, T. roseum infection can also metabolize trichothecenes that pose potential health risks to consumers. Calcium propionate (CP) is widely recognized as a food-grade antifungal agent. However, limited information is available regarding its antifungal mechanism against T. roseum and its potential application in controlling postharvest diseases of fruit. In this study, the antifungal efficacy of CP. against T. roseum was systematically evaluated both in vivo and in vitro, and its potential mechanism of action was further explored. The results demonstrated that CP inhibited spore germination and mycelial growth of T. roseum in a concentration-dependent manner, and effectively controlled the development of core rot of apple fruit, and powdery mildew of apricot and peach fruit. The antifungal mechanism is mainly that CP treatment targets the cell membrane, resulting in damage to cell membrane integrity and subsequent induction of oxidative stress, destruction of redox homeostasis, and inhibition of Ca2+/Mg2+-ATPase activity, resulting in disturbed calcium ion homeostasis and elevated intracellular Ca2+ levels. The reactive oxygen species (ROS) and calcium overload further contribute to a decline in mitochondrial membrane potential (ΔΨm), impair the function of key enzymes involved in energy metabolism (including hexokinase, malate dehydrogenase, succinate dehydrogenase, and ATP synthase), and ultimately block ATP synthesis. These events collectively lead to mitochondrial dysfunction and the suppression of energy metabolism. In vivo experiments demonstrated that treatment with CP inhibited the development of disease caused by T. roseum in fruit such as apple, peach, and apricot, and effectively maintained key quality parameters of apple fruit during postharvest storage, including weight loss rate, firmness, total soluble solids (TSS), reducing sugar content, vitamin C (Vc), and titratable acidity (TA).