Cakmak I, Marschner H
Department of Soil Science and Plant Nutrition, University of Cukurova, Adana, Turkey.
Plant Physiol. 1992 Apr;98(4):1222-7. doi: 10.1104/pp.98.4.1222.
The influence of varied Mg supply (10-1000 micromolar) and light intensity (100-580 microeinsteins per square meter per second) on the concentrations of ascorbate (AsA) and nonprotein SH-compounds and the activities of superoxide dismutase (SOD; EC 1.15.11) and the H(2)O(2) scavenging enzymes, AsA peroxidase (EC 1.11.1.7), dehydroascorbate reductase (EC 1.8.5.1), and glutathione reductase (EC 1.6.4.2) were studied in bean (Phaseolus vulgaris L.) leaves over a 13-day period. The concentrations of AsA and SH-compounds and the activities of SOD and H(2)O(2) scavenging enzymes increased with light intensity, in particular in Mg-deficient leaves. Over the 12-day period of growth for a given light intensity, the concentrations of AsA and SH-compounds and the activities of these enzymes remained more or less constant in Mg-sufficient leaves. In contrast, in Mg-deficient leaves, a progressive increase was recorded, particularly in concentrations of AsA and activities of AsA peroxidase and glutathione reductase, whereas the activities of guaiacol peroxidase and catalase were only slightly enhanced. Partial shading of Mg-deficient leaf blades for 4 days prevented chlorosis, and the activities of the O(2) (.-) and H(2)O(2) scavenging enzymes remained at a low level. The results demonstrate the role of both light intensity and Mg nutritional status on the regulation of O(2) (.-) and H(2)O(2) scavenging enzymes in chloroplasts.
研究了不同镁供应水平（10 - 1000微摩尔）和光照强度（100 - 580微爱因斯坦每平方米每秒）对菜豆（Phaseolus vulgaris L.）叶片中抗坏血酸（AsA）和非蛋白硫氢化合物浓度以及超氧化物歧化酶（SOD；EC 1.15.11）和H₂O₂清除酶——抗坏血酸过氧化物酶（EC 1.11.1.7）、脱氢抗坏血酸还原酶（EC 1.8.5.1）和谷胱甘肽还原酶（EC 1.6.4.2）活性的影响，实验为期13天。AsA和硫氢化合物的浓度以及SOD和H₂O₂清除酶的活性随光照强度增加，在缺镁叶片中尤其如此。在给定光照强度下的12天生长期间，镁充足的叶片中AsA和硫氢化合物的浓度以及这些酶的活性或多或少保持恒定。相比之下，在缺镁叶片中，这些指标呈现逐渐增加的趋势，特别是AsA浓度以及抗坏血酸过氧化物酶和谷胱甘肽还原酶的活性，而愈创木酚过氧化物酶和过氧化氢酶的活性仅略有增强。对缺镁叶片进行4天的部分遮光可防止叶片黄化，并且超氧阴离子（O₂⁻）和H₂O₂清除酶的活性保持在较低水平。结果表明光照强度和镁营养状况在叶绿体中超氧阴离子（O₂⁻）和H₂O₂清除酶调节中的作用。
