Cheeseman John M
Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA.
J Exp Bot. 2006;57(10):2435-44. doi: 10.1093/jxb/erl004. Epub 2006 Jun 9.
While H2O2 has been implicated in numerous plant environmental responses, normal levels and variabilities are poorly established, and estimates of leaf tissue concentrations span more than three orders of magnitude, even in a single species under similar conditions. Here, leaf tissue H2O2 contents under natural conditions are reported after determining (i) that H2O2 in extracts was stable with time, (ii) that H2O2 added to the extract was recovered quantitatively, and (iii) that the H2O2 calibration curve was unaffected (or quantifiably affected) by the extract. The broad applicability of the protocol and variability in leaf concentrations were demonstrated using tissue collected from several habitats in association with three, more extensive, experiments. The first involved nychthemeral studies of the mangrove, Rhizophora mangle L. Lowest H2O2 levels occurred in the early morning and near sunset, with higher levels both at midday and at night. Second, using five temperate species in Spring, concentrations were compared on a warm, sunny day and a cool, cloudy day. Higher concentrations were found on the warm day for Aesculus glabra Willd., Glechoma hederacea L., Plantago major L., and Viola soraria Willd., while there were no differences in Quercus macrocarpa Michx. Finally, the effects of elevated CO2 and ozone were examined in soybean, Glycine max L. Pioneer 93B15 under Free Air gas Concentration Enrichment (FACE) conditions. Both supplements led to elevated H2O2. Overall, mean leaf, midday, and mid-summer H2O2 concentrations ranged from 0.67 micromol (gFW)(-1) in mangrove to 3.6 micromol (gFW)(-1) in A. glabra Willd. Greatest within-species differences were only 2.5-fold in any of the studies.
虽然过氧化氢与植物的多种环境响应有关，但其正常水平和变异性尚未明确确立，即使在相似条件下的单一物种中，叶片组织浓度的估计范围也跨越了三个多数量级。本文在确定了以下三点后，报告了自然条件下叶片组织中的过氧化氢含量：（i）提取物中的过氧化氢随时间稳定；（ii）添加到提取物中的过氧化氢能够定量回收；（iii）提取物对过氧化氢校准曲线无影响（或有可量化的影响）。通过与三个更广泛的实验相关联，使用从多个栖息地收集的组织，证明了该方案的广泛适用性以及叶片浓度的变异性。第一个实验是对红树植物红树（Rhizophora mangle L.）进行昼夜研究。过氧化氢水平在清晨和接近日落时最低，中午和夜间则较高。其次，在春季使用五种温带物种，比较了温暖、晴朗天气和凉爽、多云天气下的浓度。在温暖的日子里，七叶树（Aesculus glabra Willd.）、连钱草（Glechoma hederacea L.）、大车前（Plantago major L.）和堇菜（Viola soraria Willd.）的浓度较高，而大果栎（Quercus macrocarpa Michx.）则没有差异。最后，在自由空气气体浓度富集（FACE）条件下，研究了二氧化碳和臭氧浓度升高对大豆（Glycine max L. Pioneer 93B15）的影响。两种气体添加均导致过氧化氢水平升高。总体而言，叶片、中午和仲夏时的过氧化氢平均浓度范围从红树中的0.67微摩尔/（克鲜重）（-1）到七叶树中的3.6微摩尔/（克鲜重）（-1）。在任何一项研究中，物种内的最大差异仅为2.5倍。
