Lysine and threonine supplementation promotes postharvest quality of Volvariella volvacea mushroom during low-temperature preservation via maintenance of the citrate cycle

Volvariella volvacea, the edible straw mushroom, is popular among consumers; however, its freshness is difficult to maintain at 4 °C. Spray treatment with the ubiquitin-binding enzyme E2 (UBEV2) inhibitor L345-0044 maintained the freshness of V. volvacea during storage at 4 °C for 48 h. Inhibitor treatment enhanced the ability of V. volvacea to resist cold stress by inducing overexpression of genes involved in protein translation, protein turnover, N-glycan biosynthesis, and lysine metabolism. Overexpression of saccharopine dehydrogenase genes, which participate in lysine metabolism in yeast, enhanced freezing tolerance. Anti-freezing experiments showed that the addition of l-lysine or l-threonine improved the quality of V. volvacea at 4 °C with stable soluble sugar levels, as lysine or threonine metabolism produced acetyl-CoA for maintaining the citrate cycle. Our findings revealed that supplementation with l-lysine or l-threonine prolonged the preservation time of V. volvacea for more than 24 h via maintenance of the citrate cycle.