Antifungal Effects and Postharvest Diseases Control Potential of <i>E</i>, <i>E</i>-2, 4-Nonadienal against <i>Rhizopus stolonifer</i>

Pathogenic microorganisms are a significant cause of food spoilage, adversely affecting both product quality and human health. This study evaluated the antifungal activities of 34 aldehydes against foodborne and plant pathogenic fungi, identifying 8 promising lead compounds. Among them, <i>E</i>, <i>E</i>-2, 4-nonadienal exhibited optimal effects against <i>Rhizopus stolonifer</i> with an EC₅₀ of 11.29 μg/mL. <i>In vitro</i> assays demonstrated that <i>E</i>, <i>E</i>-2, 4-nonadienal significantly impact <i>R. stolonifer</i> through both direct contact and fumigation. The preliminary mode of action (MOA) studies indicated that it effectively inhibited spore germination, disrupted ergosterol biosynthesis, and induced oxidative stress, affecting the permeability of the fungal cell membrane and altering mycelial morphology. Additionally, <i>E</i>, <i>E</i>-2, 4-nonadienal significantly reduced soft rot in spore-infected stored cherry tomatoes and showed low toxicity. Thus, aldehydes, exemplified by <i>E</i>, <i>E</i>-2, 4-nonadienal, are potential food and agricultural preservatives, offering efficiency, safety, and cost-effectiveness.