Accumulating mechanism of γ-aminobutyric acid in soybean (Glycine max L.) during germination

Summary γ-aminobutyric acid (GABA) has been found accumulating significantly in soybean seeds during germination. However, the mechanism of the accumulating process is not clear. Therefore, gene expression, enzyme activity and metabolites associated with GABA shunt in ZH 13 soybean during germination were analysed in this paper. GABA content in 5-day germinated soybean was 0.26 ± 0.016 mg g−1 DW, which was equivalent to six times concentration of original soybean. The GAD activity has a positive effect on the accumulation of GABA, as well as the GABA-T activity was found to play a significant role in the degradation of GABA. The expression levels of GmGAD and GmGABA-T may affect the GABA content by regulating the respective enzyme activities. In conclusion, upregulation of GAD and downregulation of GABA-T may cause the accumulation of GABA.