Effects of elevated CO2 on energy metabolism and γ-aminobutyric acid shunt pathway in postharvest strawberry fruit

The elevated CO2 was applied to the strawberry fruit during storage at 0 °C, in which its effects on energy metabolism and the γ-aminobutyric acid (GABA) shunt pathway were investigated. 10% and 20% CO2 maintained quality of the fruit. The energy charge of 10% and 20% CO2-treated fruit was decreased by 7.58% and 23.93% on day 12, respectively, compared with the control fruit, which was associated with the decline of NADH/NAD+. The GABA in 10% and 20% CO2-treated fruit was increased by 1.2-fold and 1.6-fold compared with the control fruit on day 12, respectively. The accumulation of GABA resulted from the decrease of GABA transaminase activity and gene expression, which may partially contribute to the decrease of NADH at later storage. These results indicated that 20% CO2 is an optimal concentration for strawberry fruit to prolong the storage to 12 days.