摘要
Dear Editor, y-Aminobutyric acid （GABA） is a non-protein amino acid （AA） metabolized via the GABA shunt; a three-enzyme pathway that includes glutamate decarboxylase （GAD）, GABA transaminases （GABA-T）, and succinic semialdehyde dehydrogenase （SSADH） （Bown and Shelp, 1997; Bouch~ and Fromm, 2004）. The majority of work on GABA, to date, has focused on its role as an inhibitory neurotransmitter in mammals. In plants, however, due to its intermediate posi- tion between carbon （C） and nitrogen （N）, the metabolism of GABA has been suggested as a modulator of C-N balance （Fair et al., 2008）. In addition, the numerous observations of a rapid accumulation of GABA in response to （a）biotic stresses has prompted different hypotheses to be postu- lated on its role including a regulator of cytosolic pH and a herbivore deterrent （Bouche and Fromm, 2004; Roberts, 2007）. Additionally, a signaling role has been hypothesized in plants, though evidence remains elusive and the debate on the dual function of GABA as a signaling molecule and as a metabolite in plants remains ongoing. In the present work, we report changes in the metabolite and transcript profiles in Arabidopsis seedlings exposed to exogenous GABA. Liquid-grown seedlings were cultured under C and N limitation to reveal a possible role of GABA as either C or N substrate and to ascertain its influence on transcriptional programs.
Dear Editor, y-Aminobutyric acid （GABA） is a non-protein amino acid （AA） metabolized via the GABA shunt; a three-enzyme pathway that includes glutamate decarboxylase （GAD）, GABA transaminases （GABA-T）, and succinic semialdehyde dehydrogenase （SSADH） （Bown and Shelp, 1997; Bouch~ and Fromm, 2004）. The majority of work on GABA, to date, has focused on its role as an inhibitory neurotransmitter in mammals. In plants, however, due to its intermediate posi- tion between carbon （C） and nitrogen （N）, the metabolism of GABA has been suggested as a modulator of C-N balance （Fair et al., 2008）. In addition, the numerous observations of a rapid accumulation of GABA in response to （a）biotic stresses has prompted different hypotheses to be postu- lated on its role including a regulator of cytosolic pH and a herbivore deterrent （Bouche and Fromm, 2004; Roberts, 2007）. Additionally, a signaling role has been hypothesized in plants, though evidence remains elusive and the debate on the dual function of GABA as a signaling molecule and as a metabolite in plants remains ongoing. In the present work, we report changes in the metabolite and transcript profiles in Arabidopsis seedlings exposed to exogenous GABA. Liquid-grown seedlings were cultured under C and N limitation to reveal a possible role of GABA as either C or N substrate and to ascertain its influence on transcriptional programs.
