Gradual drought under field conditions influences glutathione metabolism, redox balance and energy supply in spring wheat
Gradual drought under field conditions influences glutathione metabolism, redox balance and energy supply in spring wheat
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DOI：
10.1007/s00344-003-0053-4
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发表时间：
2004-03-01
影响因子：
4.8
通讯作者：
Zhang, CL
中科院分区：
文献类型：
--
作者：
Chen, KM;Gong, HJ;Zhang, CL
春小麦谷胱甘肽代谢、氧化还原平衡与能量供应在田间条件下进行了渐变干旱胁迫的研究。干旱虽然降低了总GSH和还原型GSH的水平，但GSH/GSSG(谷胱甘肽二硫化物)的比值却显著增加。胁迫下植物体内GSH生物合成前体半胱氨酸(Cys)和γ-谷氨酰半胱氨酸(Gamma-Glamylcysteine，GGC)水平及其生物合成酶--γ-谷氨酰半胱氨酸合成酶(Gamma-Glamylcystee Synthetase，GGCS)和谷胱甘肽合成酶(GSHS)的活性也显著增加。负责GSSG转化为GSH的谷胱甘肽还原酶(GR)活性也在该胁迫下增强。然而，谷胱甘肽过氧化物酶(GP)和谷胱甘肽S转移酶(GST)这两种谷胱甘肽代谢的重要酶在干旱植株中活性降低。这些结果表明，较高的GSH/GSSG比值、GSH生物合成速率及其氧化还原循环能力而不是GSH积累可能是植物抗旱性所必需的。干旱胁迫对依赖于NADP(+)的甘油醛-3-磷酸脱氢酶(G3PD)和果糖-1，6-二磷酸酶(FBPase)这两种具有暴露的巯基的关键Calvin循环酶的活性没有影响，而戊糖-磷酸途径(PPP)的关键酶--6-磷酸葡萄糖脱氢酶(6-PGD)的活性在干旱胁迫下增加。干旱胁迫下植物体内NADPH/NADP(+)、NADH/NAD(+)和ATP/ADP比值升高，表明上调植物细胞内氧化还原状态和能量供应可能是植物响应干旱胁迫的重要生理策略。在田间干旱条件下，GSH/GSSG比值、GSH生物合成速率与植物细胞氧化还原循环和氧化还原状态的高度还原状态之间存在着简单的相关性。
Glutathione (GSH) metabolism, redox balance and energy supply in spring wheat (Triticum aestivum L.) during gradual drought stress under field conditions were investigated. Although levels of total and reduced GSH were decreased, the ratio of GSH/GSSG (glutathione disulfide) was markedly increased by drought. Levels of GSH biosynthetic precursors, cysteine (Cys) and gamma-glutamylcysteine (gamma-GC), and the activities of their biosynthetic enzymes, gamma-glutamylcysteme synthetase (gamma-GCS) and glutathione synthetase (GSHS) were also significantly increased in stressed plants. Glutathione reductase (GR) activity, which is responsible for the conversion of GSSG to GSH, was also increased under this field stress. However, two other important enzymes in GSH metabolism, glutathione peroxidase (GP) and glutathione S-transferase (GST), showed decreased activity in the droughted plants. These results suggest that the higher ratio of GSH/GSSG, the rate of GSH biosynthesis and the capacity of its redox cycling rather than GSH accumulation might be essential for drought resistance of plants. Activities of the two key Calvin-cycle enzymes possessing exposed sulfhydryl groups, NADP(+)-dependent glyceraldehydes-3-phosphate dehydrogenase (G3PD) and fructose-1,6-bisphosphatase (FBPase) were not affected by drought stress, whereas, activity of the key enzyme in the pentose-phosphate pathway (PPP), 6-phosphogluconate dehydrogenase (6-PGD), increased in the droughted plants. The ratios of NADPH/NADP(+), NADH/NAD(+) and ATP/ADP increased in the droughted plants, indicating that an up-regulation of the reduced redox state and the energy supply in the plant cells might be an important physiological strategy for plants responding to drought stress. A simple correlation between the high ratio of GSH/GSSG, the rate of GSH biosynthesis and the redox cycle and the high reduction states of redox status in the plant cells was also observed under field drought.