Contribution of GABA shunt to chilling tolerance in anthurium cut flowers in response to postharvest salicylic acid treatment

Abstract

Due to the sensitivity of anthurium flowers to chilling injury (CI), its favorable temperature storage is 12.5–20°C. There is evidence that maintaining the functional γ-aminobutyric acid (GABA) shunt pathway is crucial for tolerance to postharvest chilling stress by providing energy (ATP) and reducing molecule (NADH) and minimizing reactive oxygen species (ROS) accumulation. In this experiment, the impact of salicylic acid (SA) treatment applied by postharvest stem-end dipping (2mM, 15min at 20°C) on GABA shunt pathway activity of anthurium cut flowers (cv. Sirion) storage at 4°C for 21days were investigated. The anthurium cut flowers in response to 2mM SA treatment displayed significantly higher GABA transaminase (GABA-T) activity during storage at 4°C for 21days, which coincided with lower GABA content, leading to flowers with lower spathe browning. SA treatment enhanced GABA shunt pathway activity, by enhancing GABA-T activity, during storage at 4°C, lead to consumption of GABA for providing sufficient ATP content associated with the lower H2O2 content. Also, anthurium cut flowers in response to SA treatment displayed significantly higher unsaturated/saturated fatty acids (unSFA/SFA) ratio, which can be results not only from higher energy content but also from lower phospholipase D (PLD) and lipoxygenase (LOX) activities. These findings showed that SA treatment at 2mM maintained functional GABA shunt pathway activity which leads to providing higher ATP, lower H2O2 accumulation, higher unSFA/SFA ratio, proposed that the SA can be applied as an effective procedure for improving anthurium cut flowers tolerance to postharvest chilling stress, by enhancing membrane fluidity.