LED irradiation delays postharvest senescence in pakchoi by regulating amino acid metabolism

Low-level white light-emitting diode (LED) irradiation can postpone postharvest senescence in pakchoi, however, the effect on postharvest amino acid metabolism is poorly understood. In this study, metabolomic and transcriptomic data were used to investigate amino acid metabolism in LED-treated pakchoi. Results indicated that LED irradiation had a considerable effect on the metabolism of several amino acids (histidine, cysteine and methionine, tryptophan, glycine, serine and threonine, lysine, and arginine and proline), with glycine, serine, and threonine metabolism being the most affected. The level of gene expression and metabolites related to the affected amino acids in LED-treated samples was closer to the levels in initial samples. LED irradiation was also found to increase soluble protein content, and decrease protease activity and amino acids level at 5 d of storage. These results indicate that the primary mechanism by which white LED irradiation delays pakchoi senescence is through the regulation of amino acid metabolism.