GABA shunt and polyamine degradation pathway on γ-aminobutyric acid accumulation in germinating fava bean (Vicia faba L.) under hypoxia

► Hypoxia is very helpful for accumulating GABA in germinating fava bean. ► The levels of Glu and polyamines were regulated by hypoxia treatment. ► GAD activity was regulated by hypoxia treatment and rapid growth of embryo. ► DAO was sensitive to hypoxia treatment. ► Polyamine degradation pathway supplied at least 30% of GABA formation under hypoxia.