Enhancement of postharvest chilling tolerance of anthurium cut flowers by γ-aminobutyric acid (GABA) treatments

Abstract

Anthurium cut flowers, originally a tropical flower, cannot easily be stored at low temperatures, due to the risk of chilling injury (CI). In response to chilling stress, increment of phospholipase D (PLD) enzyme activity leads to releasing unsaturated fatty acids, which under peroxidation by lipoxygenase (LOX) results to declining membrane fluidity and manifesting chilling symptoms. In this study, the effects of γ-aminobutyric acid (GABA) treatment applied by preharvest spraying (1mM) or postharvest stem-end dipping (5mM, 15min at 20°C) on CI of anthurium cut flowers (cv. Sirion) stored at 4°C for 21 days were investigated. GABA treatment at 1 and 5mM by pre and postharvest treatment, respectively, significantly delayed spathe browning. The GABA treated anthurium cut flowers exhibited significantly lower PLD and LOX activities, which coincided with a higher unsaturated fatty acids/saturated fatty acids (unSFA/SFA) ratio. Also, anthurium cut flowers treated with GABA showed lower H2O2 accumulation, which results from higher antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) activity. These results suggest that GABA treatment can be used as a useful procedure for enhancing tolerance of anthurium cut flowers to postharvest chilling injury by decreasing PLD and LOX activities coincide with enhancing antioxidant system activity, which lead to lowering ROS accumulation and promoting higher unSFA/SFA ratio and ultimately maintaining membrane integrity.