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以‘西域一号’甜瓜为试验材料,采用营养液水培法,研究了低氧胁迫下外源添加γ-氨基丁酸(GABA)对甜瓜幼苗多胺代谢的影响.结果表明:与通气对照相比,低氧胁迫处理的甜瓜幼苗谷氨酸脱羧酶(GAD)活性和GABA含量显著提高,同时多胺合成酶活性提高诱导多胺含量显著增加,但二胺氧化酶(DAO)和多胺氧化酶(PAO)活性也显著提高;根系精氨酸脱羧酶(ADC)活性提高幅度较大,导致根系游离态腐胺含量较高,而叶片鸟氨酸脱羧酶(ODC)和S-腺苷甲硫氨酸脱羧酶(SAMDC)活性提高幅度较大,导致叶片游离态亚精胺(Spd)含量较高;根系游离态DAO和PAO活性显著低于叶片,其细胞壁结合态PAO活性显著高于叶片.与低氧胁迫处理相比,低氧胁迫下外源添加GABA处理的甜瓜幼苗叶片和根系中GABA和谷氨酸含量均显著提高,而GAD活性显著降低;精氨酸、鸟氨酸、甲硫氨酸含量的提高促使多胺合成酶活性显著提高,从而诱导多胺含量显著增加,DAO和PAO活性显著降低.
The effect of γ-aminobutyric acid (GABA) supplementation on the polyamines metabolism in melon seedlings under the condition of hypoxia stress was studied by using hydroponic hydroponics using ’Western Region No.1’ melon as test material. The results showed that: Compared with the control, the activities of glutamic acid decarboxylase (GAD) and GABA in melon seedlings treated with hypoxia stress increased significantly, while the polyamine synthetase activity increased significantly, while the contents of polyamine and diamine oxidase (DAO) The activity of oxidase (PAO) also increased significantly. The increase of arginine decarboxylase (ADC) activity in root increased greatly, resulting in higher content of free putrescine in roots. However, the activities of ornithine decarboxylase (ODC) The increase of the activities of SAMDC was higher than that of the leaves, leading to the higher content of free spermidine (Spd) in leaves. The activities of free radical DAO and PAO in roots were significantly lower than those in leaves, and the activities of PAO in cell wall were significantly higher than those in leaves. Compared with hypoxia stress, the contents of GABA and glutamic acid in GABA-treated melon seedling leaves and roots under hypoxia stress were significantly increased, while the GAD activity was significantly decreased; arginine, ornithine, methionine Increased acidity leads to significant polyamine synthetase activity High, thereby inducing a significant increase in polyamine content, DAO, and PAO activity was decreased.