Amelioration of postharvest chilling injury in anthurium cut flowers by γ-aminobutyric acid (GABA) treatments

The optimum temperature storage of anthurium flowers is 12.5-20 °C because they are very sensitive to chilling injury (CI). CI is associated with the loss of membrane integrity which can be aligned to phenolic oxidation due to polyphenol oxidase (PPO) activity, the enzyme responsible for tissue browning. The increment of phenylalanine ammonia-lyase (PAL) activity, the enzyme responsible for phenols accumulation, in response to chilling stress has been considered as defense mechanism to chilling stress. In this study, the effects of 0, 1, 5, 10, 15 and 20 mM γ-aminobutyric acid (GABA) treatment applied by preharvest spraying or postharvest stem-end dipping (15 min at 20 °C) on CI of anthurium flowers (cv. Sirion) stored at 4 °C for 21 days was investigated. CI symptoms were accompanied by spathe browning and increase in electrolyte leakage as well as malondialdehyde (MDA) content. GABA treatment at 1 and 5 mM by pre and postharvest treatment, respectively, delayed spathe browning and increases in electrolyte leakage and MDA accumulation. The GABA treated anthurium cut flowers exhibited significantly higher PAL enzyme activity, associated with lower PPO activity. Higher PAL enzyme activity in anthurium cut flowers treated with GABA coincided with higher total phenol accumulation and higher DPPH scavenging activity than control flowers during storage at 4 °C for 21 days. Also, proline content in anthurium cut flowers treated with GABA was significantly higher than control flowers during storage. These results suggest that GABA treatment can be used as a useful technology for enhancing tolerance of anthurium cut flowers to postharvest chilling injury by increasing total phenol and proline accumulation and decreasing MDA content, and thus maintaining membrane integrity.