γ-Amino butyric acid （GABA） and proline play a crucial role in protecting plants during various environmental stresses. Their synthesis is from the common precursor glutamic acid, which is catalyzed by glutamate de...γ-Amino butyric acid （GABA） and proline play a crucial role in protecting plants during various environmental stresses. Their synthesis is from the common precursor glutamic acid, which is catalyzed by glutamate decarboxylase and △1-pyrroline-5-carboxylate synthetase respectively. However, the dominant pathway under water stress has not yet been established. To explore this, excised tobacco leaves were used to simulate a water-stress condition. The results showed GABA content was much higher than that of proline in leaves under water-deficit and non-water-deficit conditions. Specifically, the amount of GABA significantly increased compared to proline under continuous water loss for 16 h, indicating that GABA biosynthesis is the dominant pathway from glutamic acid metabolism under these conditions. Quantitative reverse transcription polymerase chain reaction and protein Western gel-blot analysis further confirmed this. To explore the function of GABA accumulation, a system producing superoxide anion （O 2 - ）, peroxide hydrogen （H 2 O 2 ）, and singlet oxygen （ 1 O 2 ） was employed to investigate the scavenging role on free-radical production. The results demonstrated that the scavenging ability of GABA for O 2 - , H 2 O 2 , and 1 O 2 was significantly higher than that of proline. This indicated that GABA acts as an effective osmolyte to reduce the production of reactive oxygen species under water stress.展开更多
利用植物乳杆菌(Lactobacillus plantarum dy-1)发酵小麦胚芽,研究其发酵前后营养品质与贮藏特性的变化。结果表明,Lactobacillus plantarum dy-1中存在谷氨酸脱羧酶(GAD),能够转化L-谷氨酸生成γ-氨基丁酸(GABA);发酵后的小麦胚芽总游...利用植物乳杆菌(Lactobacillus plantarum dy-1)发酵小麦胚芽,研究其发酵前后营养品质与贮藏特性的变化。结果表明,Lactobacillus plantarum dy-1中存在谷氨酸脱羧酶(GAD),能够转化L-谷氨酸生成γ-氨基丁酸(GABA);发酵后的小麦胚芽总游离氨基酸的含量提高了13.64倍,其中天冬氨酸、亮氨酸、γ-氨基丁酸以及蛋氨酸、赖氨酸等增加显著;发酵过程中植酸酶活性增强,抗营养因子植酸的含量下降;发酵麦胚的脂肪酶活力比发酵前降低55.31%,脂肪氧化酶活力降低76.32%;顶空固相微萃取-气质联用(SPME-GC-MS)分析显示,发酵麦胚的贮藏特性发生显著改变,经过60 d的室温贮藏,发酵麦胚的氧化酸败程度明显低于未发酵麦胚。因此,乳酸菌发酵小麦胚芽可显著改善其营养品质与贮藏特性,采用该方法加工的小麦胚芽可作为食品营养强化的原料或食品配料。展开更多
基金supported by the National Natural Science Foundation of China(No.30700427)Outstanding Young Talent Fund from Key Projects in Hubei Province Natural Science Foundation(No.2010CDA099)Academic Innovation Team for Plant Development and Genetics in South-Central University for Nationalities
文摘γ-Amino butyric acid （GABA） and proline play a crucial role in protecting plants during various environmental stresses. Their synthesis is from the common precursor glutamic acid, which is catalyzed by glutamate decarboxylase and △1-pyrroline-5-carboxylate synthetase respectively. However, the dominant pathway under water stress has not yet been established. To explore this, excised tobacco leaves were used to simulate a water-stress condition. The results showed GABA content was much higher than that of proline in leaves under water-deficit and non-water-deficit conditions. Specifically, the amount of GABA significantly increased compared to proline under continuous water loss for 16 h, indicating that GABA biosynthesis is the dominant pathway from glutamic acid metabolism under these conditions. Quantitative reverse transcription polymerase chain reaction and protein Western gel-blot analysis further confirmed this. To explore the function of GABA accumulation, a system producing superoxide anion （O 2 - ）, peroxide hydrogen （H 2 O 2 ）, and singlet oxygen （ 1 O 2 ） was employed to investigate the scavenging role on free-radical production. The results demonstrated that the scavenging ability of GABA for O 2 - , H 2 O 2 , and 1 O 2 was significantly higher than that of proline. This indicated that GABA acts as an effective osmolyte to reduce the production of reactive oxygen species under water stress.
文摘利用植物乳杆菌(Lactobacillus plantarum dy-1)发酵小麦胚芽,研究其发酵前后营养品质与贮藏特性的变化。结果表明,Lactobacillus plantarum dy-1中存在谷氨酸脱羧酶(GAD),能够转化L-谷氨酸生成γ-氨基丁酸(GABA);发酵后的小麦胚芽总游离氨基酸的含量提高了13.64倍,其中天冬氨酸、亮氨酸、γ-氨基丁酸以及蛋氨酸、赖氨酸等增加显著;发酵过程中植酸酶活性增强,抗营养因子植酸的含量下降;发酵麦胚的脂肪酶活力比发酵前降低55.31%,脂肪氧化酶活力降低76.32%;顶空固相微萃取-气质联用(SPME-GC-MS)分析显示,发酵麦胚的贮藏特性发生显著改变,经过60 d的室温贮藏,发酵麦胚的氧化酸败程度明显低于未发酵麦胚。因此,乳酸菌发酵小麦胚芽可显著改善其营养品质与贮藏特性,采用该方法加工的小麦胚芽可作为食品营养强化的原料或食品配料。
