Contribution of Putrescine and Glutamic Acid on γ-Aminobutyric Acid Accumulation of Malus baccata Borkh. Roots under Suboptimal Low Root-Zone Temperature

• Published in: Agronomy (Basel) 2023-08, Vol.13 (8), p.1989
• Main Authors: Lu, Xiaochen, Zhao, Meiqi, Zhou, Enda, Ma, Huaiyu, Lyu, Deguo
• Format: Article
• Language: English
• Subjects: 4-Aminobutyrate transaminase; Abiotic stress; Accumulation; Catabolism; Catalase; Dehydrogenases; Diamines; Genetic transformation; Glutamic acid; Hydrogen peroxide; Ions; Low temperature; Malus baccata; Malus baccata Borkh; Metabolism; Nitrogen; Oxidative stress; Peroxidase; Physiology; Plant growth; Plant resistance; polyamine; Polyamines; Putrescine; Roots; Spermidine; Spermine; suboptimal low root-zone temperature; Superoxide anions; Superoxide dismutase; Temperature; Temperature tolerance; Transaminase; γ-Aminobutyric acid
• ISSN: 2073-4395; 2073-4395
• DOI: 10.3390/agronomy13081989

GABA (γ-aminobutyric acid) is found in plants and accumulates rapidly under stresses. However, the contributions of glutamic acid and a (Glu)-derived pathway and polyamines (PAs) catabolism pathway on GABA accumulation and the regulatory effects of exogenous putrescine (Put) on a GABA shunt under suboptimal low root-zone temperatures remain unknown. Our results showed that suboptimal low root-zone temperatures (treatment L) significantly increased GABA contents and GABA transaminase (GABA-T) activities. The contribution rate of the PAs catabolism pathway increased from 20.60% to 43.31%. Treatment L induced oxidative stress in Malus baccata Borkh. roots. Exogenous Put increased the contents of endogenous Put, spermine (Spm), and spermidine (Spd), promoted the transformation of PAs, increased the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and decreased the contents of hydrogen peroxide (H2O2), superoxide anion (O2∙−), and malondialdehyde (MDA). Meanwhile, contrasting results were observed after aminoguanidine (AG, an inhibitor of diamine oxidase) application. These findings revealed that the Glu-derived pathway is the main route of GABA synthesis. The contribution rate of the Pas catabolism pathway increased gradually with the extension of treatment time, and the treatment of exogenous Put significantly improved the tolerance of Malus baccata Borkh. Roots to suboptimal low temperature by regulating the transformation of Pas, GABA shunt, and the antioxidant system.