[Effects of exogenous gamma-aminobutyric acid on antioxidant enzyme activity and reactive oxygen content in muskmelon seedlings under nutrient solution hypoxia stress].

The effects of exogenous gamma-aminobutyric acid (GABA) on antioxidant defense system and reactive oxygen species (ROS) in seedlings of two varieties with different resistance to hypoxia stress were studied under hypoxia stress in a nutrient solution culture system. The results showed that GABA treatments enhanced the activities of antioxidant enzyme including SOD (Fig. 1), POD (Fig. 2), CAT (Fig. 3), while the concentrations of H2O2 (Fig. 4), O(-.)2 (Fig. 5), MDA (Fig. 6) decreased under hypoxia stress. Among the treatments of three different GABA concentrations, the effect of 50 mmol/L GABA treatment was better than that of 25 mmol/L GABA and 100 mmol/L GABA treatments. The effect of treatment with GABA in "Dongfang xingguang" seedlings, which had stronger hypoxia-resistance to hypoxia stress, were better than that in "Xiyu No.1" seedlings which had lower hypoxia-resistance. It indicates that GABA treatment of exogenous spraying to leaves can increase the activities of antioxidant enzyme under the hypoxia stress and plays an important role in enhancing the resistance to hypoxia stress of muskmelon seedlings through keeping low ROS contents.