Multi-omics Profiling Reveals the Effects of Exogenous Leucine on Carbohydrate and Energy Metabolism in Broccoli

To investigate the effects and molecular basis of leucine on carbohydrate and energy homeostasis in postharvest broccoli, an integrated transcriptomic and metabolomic analysis was conducted on postharvest broccoli treated with leucine soaking. Results showed that leucine treatment elevated the ATP and ADP contents and energy charge, which consequently enhanced the cellular energy status of postharvest broccoli. Leucine treatment suppressed alcoholic fermentation by down-regulating pyruvate decarboxylase and alcohol dehydrogenase expression. It enhanced the tricarboxylic acid (TCA) cycle by up-regulating the expression of pyruvate dehydrogenase E1 and E2 subunits, citrate synthase, and malate dehydrogenase and promoting glycolysis and the conversion of glucose into pyruvate, thereby directing a greater flux of pyruvate into the TCA cycle. Leucine treatment improved oxidative phosphorylation, effectively converting the energy stored in reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) into ATP. The findings offer a theoretical basis for developing strategies to improve energy status and thereby extending the commercial shelf life of postharvest broccoli.