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以甜瓜品种‘金辉1号’为试材,采用深液流水培法,研究外源γ-氨基丁酸(GABA)对短期盐碱胁迫下甜瓜幼苗叶绿体活性氧代谢的调控作用.结果表明:盐碱胁迫显著提高了甜瓜叶绿体内光合色素、丙二醛(MDA)和过氧化氢(H_2O_2)含量及超氧阴离子(O_2~·)产生速率;增加抗坏血酸(AsA)和谷胱甘肽(GSH)等抗氧化物质含量;明显抑制H~+-ATP酶(H~+-ATPase)和H~+-焦磷酸酶(H~+-PPiase)活性.外源叶面喷施GABA有效抑制了盐碱胁迫引起的叶绿体内O_2、H_2O_2和MDA的积累缓解了光合色素增加的趋势;显著提高SOD和AsA-GSH循环各个酶的活性,增加了AsA和GSH库,降低了AsA/DHA和GSH/GSSH比值,增强了H~+-ATPase和H~+-PPiase活性.表明外源GABA能加快叶绿体内活性氧代谢,促进AsA-GSH循环的运转,维持细胞膜的渗透性,进而缓解了盐碱胁迫引起的氧化伤害.
The melon cultivar ’Jinhui 1’ was used as material to study the regulation of exogenous γ-aminobutyric acid (GABA) on the active oxygen metabolism of chloroplast in melon seedling under salt and alkali stress. The results showed that salt Alkali stress significantly increased the content of photosynthetic pigments, malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2) and the production rate of superoxide anion (O 2 - ·) in melon chloroplast; increased the content of AsA and GSH, (H ~ + -ATPase) and H ~ + -PPiase (H ~ + -PPiase) activities were significantly inhibited by exogenous foliar spraying of GABA The accumulation of O 2, H 2 O 2 and MDA in chloroplasts induced by stress alleviated the trend of photosynthetic pigment increasing, significantly increased the activities of SOD and AsA-GSH cycle enzymes, increased the AsA and GSH pools and decreased the AsA / DHA and GSH / GSSH ratios , Which enhanced the activity of H ~ + -ATPase and H ~ + -PPiase, indicating that exogenous GABA can accelerate the metabolism of reactive oxygen species in chloroplasts, promote the operation of AsA-GSH cycle and maintain the permeability of cell membrane, Oxidative damage.