Under pre and postharvest GABA treatments, anthurium cut
flowers only showed a higher GABA content than control flowers
after 7 days, whereas after 14 and 21 days the GABA content was
lower than control flowers (Table 1). This result may be due to
exogenous treated GABA uptake by flower, leading to higher GABA
content after 7 days. As also shown in Table 1, GAD activity
increased in flowers during storage, but pre and postharvest GABA
treatments decreased its activity. In agreement with our results,
Wang et al. (2014a) suggested that the lower GAD enzyme activity
in melon roots treated with GABA was due to higher endogenous
GABA accumulation which achieved by uptake exogenous GABA
treatment. Also, our results showed that the GABA-T activity
increased in flowers; however, after 14 and 21 days of storage,
flowers treated with GABA had higher GABA-T activity in comparison
with control flowers (Table 1). These results suggested that
GABA treatment, by activating a negative feedback mechanism,
triggered a decrease in GABA biosynthesis and an increase in GABA
degradation during storage. This response is consistent with the
lower GABA content in treated flowers after 21 days. In muskmelon
seedlings roots treated with GABA under salt stress, owing to lower
GAD enzyme activity and higher GABA-T enzyme activity, had
lower endogenous GABA content. This response could contribute to
salt tolerance in roots via providing succinate for TCA cycle and
ultimately supplying ATP and NADH (Hu et al., 2015).
In flowers during storage at 4 C, energy charge declined