摘要:Polyamines are a potential source of γ-aminobutyric acid (GABA) in plants under abiotic stress. However, studies on GABA enrichment in tea mostly focus on the GABA shunt, while the correlation between polyamine degradation and GABA formation in tea is largely unknown. In this study, tea plants responded to exogenous putrescine, resulting in a significant increase in GABA content, while the glutamate level did not change. At the same time, five
copper-containing amine oxidase (
CuAO) and eight
aminoaldehyde dehydrogenase (
AMADH) genes involved in the putrescine-derived GABA pathway were identified from the Tea Plant Information Archive. Expression analysis indicated that
CsCuAO1,
CsCuAO3 as well as
CsAMADH1 were induced to play an important function in response to exogenous putrescine. Thus, the three genes were cloned and the catalytic efficiency of soluble recombinant proteins was determined.
CsCuAOs and
CsAMADH1 exhibited indispensable functions in the GABA production from putrescine in vitro. Subcellular localization assays indicated that
CsAMADH1 was localized in plastid, while both
CsCuAO1 and
CsCuAO3 were localized in peroxisome. In addition, the synergistic effects of
CsCuAOs and
CsAMADH1 were investigated by a transient co-expression system in
Nicotiana benthamiana. Our data suggest that these three genes regulate the accumulation of GABA in tea by participating in the polyamine degradation pathway and improve the content of GABA in tea to a certain extent. The results will greatly contribute to the production of GABA tea.