The promising application of a β-glucosidase inhibitor in the postharvest management of Volvariella volvacea

Cryogenic autolysis of Volvariella volvacea restricts the postharvest storage and sale of this commercially cultivated mushroom. Previous studies have shown that the specific ubiquitin-binding enzyme E2 (UBEV2) inhibitor (L345-0044) is an effective agent to prevent cryogenic autolysis. The safety of L345-0044 as a food preservative is debatable. Thus, it is essential to find a safer food additive for the preservation of V. volvacea. In this study, absolute quantitative transcriptome and metabolome analyses were performed to analyze the gene and metabolite expression profiles of the fruiting bodies treated with L345-0044 at 4 °C. Correlative pathway analysis of the associated metabolites from the correlation analysis of differentially expressed metabolites and genes (> 3) screened out the pathways of tyrosine metabolism and carbon metabolism (Impact > 1) in which tyrosinase and β-glucosidase were the two most strongly associated enzymes. qPCR confirmed that chilling stress (CS) induced abnormal up-regulation of β-glucosidase (BGVV1) and tyrosinase. Western blot and enzyme activity assays further confirmed our results that CS-induced cryogenic autolysis could be alleviated by inhibitors of β-glucosidase and tyrosinase. The activities of β-glucosidase and tyrosinase were increased by 23.34 % and by 250.34 %, respectively, after CS treatment for 24 h but were reduced by 27.25 % and by 73.20 %, respectively, after treatment with inhibitors that included conduritol B epoxide and arbutin, respectively. Among the inhibitors, D-Glucono-1,5-lactone prevented autolysis at 4 °C for more than 24 h. As a safe conventional food additive, its excellent performance in preventing autolysis indicates that it has a very promising application in the postharvest management of V. volvacea.