Ca2+ and aminoguanidine on γ-aminobutyric acid accumulation in germinating soybean under hypoxia–NaCl stress
Runqiang Yang, Yuanxin Guo, Shufang Wang, Zhenxin Gu
College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu, PR China
Gamma-aminobutyric acid (GABA), a nonproteinous amino acid with some benefits on human health, is synthesized by GABA-shunt and the polyamine degradation pathway in plants. The regulation of Ca2+ and aminoguanidine on GABA accumulation in germinating soybean (Glycine max L.) under hypoxia-NaCl stress was investigated in this study. Exogenous Ca2+ increased GABA content significantly by enhancing glutamate decarboxylase gene expression and its activity. Addition of ethylene glycol tetra-acetic acid into the culture solution reduced GABA content greatly due to the inhibition of glutamate decarboxylase activity. Aminoguanidine reduced over 85% of diamine oxidase activity, and 33.28% and 36.35% of GABA content in cotyledon and embryo, respectively. Under hypoxia–NaCl stress, the polyamine degradation pathway contributed 31.61–39.43% of the GABA formation in germinating soybean.
Keywords: aminoguanidine, Ca2+, γ-aminobutyric acid, germinating soybean, hypoxia–NaCl stress