Trans-2-hexenal inhibits the growth of imazalil-resistant Penicillium digitatum Pdw03 and delays green mold in postharvest citrus

This study investigated the efficacy of trans-2-hexenal in preventing green mold on postharvest citrus fruit and its mode of action against imazalil-resistant Penicillium digitatum Pdw03. Trans-2-hexenal inhibited Pdw03 at a minimum inhibitory concentration (MIC) and a minimum fungicidal concentration (MFC) of 0.25 mL L-1. Trans-2-hexenal reduced the incidence of green mold, which is a plant volatile compound with potent antifungal properties. Ultrastructural analysis revealed that trans-2-hexenal altered the mitochondrial structure of Pdw03. Trans-2-hexenal also increased the amount of reactive oxygen species, which hindered mitochondrial energy metabolism of Pdw03, resulting in mitochondrial structural damage and malfunction, and a decrease in mito-chondrial membrane potential. In addition, RNA-seq analysis revealed that trans-2-hexenal altered the expres-sion of some energy metabolism genes associated with the tricarboxylic acid (TCA) cycle, glycolysis, and oxidative phosphorylation of Pdw03. Superoxide dismutase, catalase, glutathione S-transferase, and glutathione peroxidase activities were altered, and expression of the relevant gene was also quantified by real-time fluo-rescence quantitative PCR. Trans-2-hexenal damaged ribosomes, primarily by downregulation of the ribosomal structural component-associated genes RPL3, RPS18, RPL12, RPL26, RPL13A, RPL9, RPL23, and RPL4, and then by reducing protein synthesis to achieve the inhibitory effect.

Automated summary

This study investigated the efficacy of trans-2-hexenal in preventing green mold on postharvest citrus fruit and its mode of action against imazalil-resistant Penicillium digitatum Pdw03. Trans-2-hexenal inhibited Pdw03 growth at a minimum inhibitory concentration (MIC) and a minimum fungicidal concentration (MFC) of 0.25 mL L-1. It was found that trans-2-hexenal altered the mitochondrial structure of Pdw03, increased reactive oxygen species production, and affected the expression of energy metabolism genes. This compound also damaged ribosomes and reduced protein synthesis to achieve the inhibitory effect.