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Accumulation of γ-aminobutyric acid in germinated soybean (Glycine max L.) in relation to glutamate decarboxylase and diamine oxidase activity induced by additives under hypoxia

Guo, Yuanxin, Yang, Runqiang, Chen, Hui, Song, Yu, Gu, Zhenxin
European food research & technology 2012 v.234 no.4 pp. 679-687
Glycine max, additive effect, additives, amine oxidase (copper-containing), arginine, calcium chloride, cotyledons, enzyme activity, foods, gamma-aminobutyric acid, glutamate decarboxylase, glutamates, hypoxia, oxidation, plant tissues, pyridoxal phosphate, sodium chloride, soybeans
High levels of γ-aminobutyric acid (GABA) accumulate in plant tissues under various stresses and exogenous additives. The purpose of this research is to provide an effective finding that can prove a rapid accumulation of GABA in germinated soybean (Glycine max L.) in response to different additives under hypoxia. Hypoxia-induced GABA accumulation in soybean embryo resulted in part from polyamine oxidation. Response to different concentration of glutamate (Glu), pyridoxal phosphate, arginine, CuCl2, NaCl, and CaCl2, a significant difference including GABA accumulation, changes of Glutamate decarboxylase (GAD), and Diamine oxidase activity (DAO) activity in germinated soybean under hypoxia occurred (p < 0.05) and the maximum accumulation of GABA were 4.07, 3.02, 3.50, 3.26, 4.00, and 3.30 g kg−1 DW respectively, which were significantly higher than those germinated soybean under normal culture (CK) and hypoxia culture (CK0) (p < 0.05). The GAD and DAO have different distributions in cotyledon and embryo of germinated soybean, and the enzyme activity mainly located in embryo of germinated soybean. Germinated soybean is a good resource of GABA-rich food. Different additives have significant effects on GABA production, among which Glu and NaCl are ideal material for GABA accumulation.