Schwanz P, Polle A
Albert-Ludwigs Universität Freiburg, Institut für Forstbotanik und Baumphysiologie, Professur für Baumphysiologie, Am Flughafen 17, D-79085 Freiburg, Germany.
Georg-August-Universität Göttingen, Forstbotanisches Institut, Abteilung I: Forstbotanik und Baumphysiologie, Büsgenweg 2, D-37077 Göttingen, Germany.
New Phytol. 1998 Nov;140(3):411-423. doi: 10.1111/j.1469-8137.1998.00290.x.
The aim of the present study was to investigate the effects of elevated CO on the antioxidative systems and the contents of pigments, soluble protein and lipid peroxidation in leaves of adult oaks, Quercus pubescens and Quercus ilex, grown at naturally enriched CO concentrations. For this purpose, a field study was conducted at two CO springs in Central Italy. Measurements of the pre-dawn water potentials indicated less drought stress in trees close to CO springs than in those grown at ambient CO concentrations. Most leaf constituents investigated showed significant variability between sampling dates, species and sites. The foliar contents of protein and chlorophylls were not affected in trees grown close to the CO vents compared with those in ambient conditions. Increases in glutathione and other soluble thiols were observed, but these responses might have been caused by a low pollution of the vents with sulphurous gases. At CO vents, glutathione reductase was unaffected, and superoxide dismutase activity was significantly diminished, in both species. Generally, the activities of catalase, guaiacol peroxidase and ascorbate peroxidase as well as the sum of dehydroascorbate and ascorbate were decreased in leaves from trees grown in naturally CO -enriched environments compared with those grown at ambient CO concentrations. The reduction in protective enzymes did not result in increased lipid peroxidation, but increased monodehydroascorbate radical reductase and dehydroascorbate reductase activities found in leaves of Q. pubescens suggest that the smaller pool of ascorbate was subjected to higher turnover rates. These data show that changes in leaf physiology persist, even after lifetime exposure to enhanced atmospheric CO . The results suggest that the down-regulation of protective systems, which has also previously been found in young trees or seedlings under controlled exposure to elevated CO concentrations, might reflect a realistic response of antioxidative defences in mature trees in a future high-CO world.
本研究的目的是调查在自然富集二氧化碳浓度环境下生长的成年栎树（柔毛栎和冬青栎）叶片中，二氧化碳浓度升高对其抗氧化系统、色素含量、可溶性蛋白质含量以及脂质过氧化的影响。为此，在意大利中部的两个二氧化碳泉进行了一项田间研究。黎明前水势的测量结果表明，靠近二氧化碳泉生长的树木比在环境二氧化碳浓度下生长的树木遭受的干旱胁迫更小。所调查的大多数叶片成分在采样日期、物种和地点之间存在显著差异。与环境条件下的树木相比，靠近二氧化碳排放口生长的树木叶片中的蛋白质和叶绿素含量未受影响。观察到谷胱甘肽和其他可溶性硫醇有所增加，但这些反应可能是由于排放口含硫气体污染较低所致。在二氧化碳排放口，两种栎树的谷胱甘肽还原酶均未受影响，而过氧化物歧化酶活性显著降低。一般来说，与在环境二氧化碳浓度下生长的树木相比，在自然富集二氧化碳环境下生长的树木叶片中过氧化氢酶、愈创木酚过氧化物酶和抗坏血酸过氧化物酶的活性以及脱氢抗坏血酸和抗坏血酸的总量均有所降低。保护酶活性的降低并未导致脂质过氧化增加，但柔毛栎叶片中发现的单脱氢抗坏血酸自由基还原酶和脱氢抗坏血酸还原酶活性增加表明，较小的抗坏血酸库周转率更高。这些数据表明，即使在一生都暴露于升高的大气二氧化碳环境之后，叶片生理变化仍然存在。结果表明，此前在受控暴露于升高二氧化碳浓度下的幼树或幼苗中也发现的保护系统下调，可能反映了在未来高二氧化碳世界中成熟树木抗氧化防御的实际反应。
