Chiu, G. Z., Shelp, B. J., Bowley, S. R., DeEll, J. R. and Bozzo, G. G. 2015. Controlled atmosphere-related injury in ‘Honeycrisp’ apples is associated with γ-aminobutyrate accumulation. Can. J. Plant Sci. 95: 879-886. ‘Honeycrisp’ apples (Malus×domestica Borkh.), including fruit treated with the ethylene antagonist 1-methylcyclopropene (1-MCP), can be susceptible to controlled atmosphere (CA)-related injury of the flesh tissue during storage. To better understand the biomarkers associated with this physiological disorder, we compared the temporal responses of the universal stress signature, γ-aminobutyrate (GABA), and visual symptoms of CA-related injury in apples subjected to elevated CO₂. Fruit were treated with or without 1-MCP prior to CA [2.5 kPa O₂, 5 (elevated) or 0.03 (ambient) kPa CO₂] storage at either 3 or 20°C for up to 24 wk. At 20°C, 1-MCP-treated apples displayed symptoms of CA-related injury by 3 wk of elevated CO₂ storage; a similar 15% disorder incidence was apparent by 6 wk in non 1-MCP-treated fruit. A maximal incidence of 30% for this disorder occurred after 24 wk at 3°C in fruit held at elevated CO₂, regardless of 1-MCP treatment. At 20°C, GABA levels were 48% higher within 6 wk of the transfer of 1-MCP-treated fruit to elevated CO₂. At 3°C, a 2.6-fold increase in GABA level occurred by week 6 of elevated CO₂ storage, and was maintained for an additional 18 wk thereafter; a similar change in GABA level was apparent in non 1-MCP-treated fruit, albeit delayed until week 18 of storage. These findings indicate that shifts in GABA are associated with the onset of visual symptoms of CA-related injury in ‘Honeycrisp’ fruit in response to elevated CO₂, regardless of 1-MCP.