Dual mechanisms regulating glutamate decarboxylases and accumulation of gamma-aminobutyric acid in tea (Camellia sinensis) leaves exposed to multiple stresses

Abstract

γ-Aminobutyric acid (GABA) is one of the major inhibitory neurotransmitters in the central nervous system. It has multiple positive effects on mammalian physiology and is an important bioactive component of tea (Camellia sinensis). GABA generally occurs at a very low level in plants but GABA content increases substantially after exposure to a range of stresses, especially oxygen-deficiency. During processing of tea leaves, a combination of anoxic stress and mechanical damage are essential for the high accumulation of GABA. This is believed to be initiated by a change in glutamate decarboxylase activity, but the underlying mechanisms are unclear. In the present study we characterized factors regulating the expression and activity of three tea glutamate decarboxylase genes (CsGAD1, 2, and 3), and their encoded enzymes. The results suggests that, unlike the model plant Arabidopsis thaliana, there are dual mechanisms regulating the accumulation of GABA in tea leaves exposed to multiple stresses, including activation of CsGAD1 enzymatic activity by calmodulin upon the onset of the stress and accumulation of high levels of CsGAD2 mRNA induced by a combination of anoxic stress and mechanical damage.

Accumulating mechanism of γ‐aminobutyric acid in soybean (Glycine max L.) during germination

“…Bars with different letters are significantly different (P < 0.05). Mei et al, 2016). This conclusion is similar to ours, which suggested that the GAD activity has a positive effect on GABA content, and GABA-T has made an immense contribution in the declining stage of GABA content.…”

“…The GABA content has a dramatic accumulation in the postharvest storage period in tomatoes, and GAD and GABA‐T may play crucial roles in the accumulation process (Akihiro et al ., ; Mae et al ., ; Mei et al ., ). This conclusion is similar to ours, which suggested that the GAD activity has a positive effect on GABA content, and GABA‐T has made an immense contribution in the declining stage of GABA content.…”

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“…L-Glutamicacid was used to make the standard curve. Each amino acid content was determined as described by Mei et al (2016).…”

A Data-Independent-Acquisition-based proteomic approach towards understanding the acclimation strategy ofMicrochloropsis gaditanaCCMP526 in hypersaline conditions

“…Plants produce Y-aminobutyrate by irreversible α-decarboxylation of glutamate by glutamate decarboxylase. GABA acts as a natural defense against pests, and it is also associated with stress response in tobacco and Camellia sinensis (tea) plants (McLean et al, 2003; Mei et al, 2016).…”