Fig. 2: Impact of elevated CO2 on the levels of GABA and related metabolites in ‘Empire’ apple fruit under low-temperature/low-O2 storage for up to 16 weeks.

Panels a-f represent time-course profiles for TAA, glutamate, alanine, GHB and succinate, respectively. Storage conditions: 0 °C, 2.5 kPa O2 and 5 kPa (●) or 0.03 kPa (○) CO2. All the data represent the mean of four treatment replicates, each being the average of three to four subsamples. The error bar above 0 wk represents the least significant difference at the P ≤ 0.05 level. Note that the y-axis varies among the panels. GABA 4-aminobutyrate, GHB 4-hydroxybutyrate, TAA total amino acids