本研究旨在探討兩種不同發芽型態的豆類，其γ-胺基丁酸 (Gamma-aminobutyric acid; GABA) 形成途徑之比較，採用地下型發芽型態的紅豆 (Vigna angularis高雄九號；ABK9) 及地上型發芽型態的大豆 (Glycine hispida Max台南二號；ST2) 為原料，測定兩者發芽過程中GABA含量、多胺含量、麩胺酸脫羧酶 (glutamate decarboxylase; GAD) 活性、二胺氧化酶 (diamine oxidase; DAO) 活性及多胺氧化酶 (polyamine oxidase; PAO) 活性等之變化。結果顯示ABK9豆芽主要透過GAD轉化麩胺酸生成GABA；雖然ST2發芽初期一至五天其GABA生成量也與GAD活性呈正相關，然而ST2在發芽後期即第五天後其GABA含量卻不受GAD活性下降的影響而持續增加。發芽過程中確有多胺含量減少以及DAO和PAO活性增加的趨勢，此意涵發芽五天後是透過多胺的氧化分解作用生成GABA。

The aim of this study was to compare the biosynthetic pathways of γ-aminobutyric acid (GABA) between two legume seeds with different germination types. Hypogeal adzuki bean (Vigna angularis Kaohsiung No.
9; ABK9) and epigeal soybean (Glycine hispida Max Tainan No. 2; ST2) were selected to determine the changes of GABA content, polyamine content, glutamate decarboxylase (GAD) activity, diamine oxidase (DAO) activity and polyamine oxidase (PAO), respectively, during their germination. The results showed that formation of GABA in ABK9 during germination mainly resulted from transforming glutamate into GABA by GAD. 1-5 days after germination, ST2 also showed the GABA content positively correlated with GAD activity. However, the increase of GABA content of ST2 after the 5th day post-germination was not affected by the decreased GAD activity. The fact that decrease of polyamine content and increase of DAO and PAO activity during germination implies that GABA in ST2 sprouts might result from the oxidation of polyamines after the 5th day post-germination.