Instituto de Botânica, Núcleo de Pesquisa em Ecologia, PO Box 68041, 04045-972, SP, Brazil.
Instituto de Botânica, Núcleo de Pesquisa em Ecologia, PO Box 68041, 04045-972, SP, Brazil.
Sci Total Environ. 2018 Jun 1;625:382-393. doi: 10.1016/j.scitotenv.2017.12.255. Epub 2017 Dec 29.
The extensive land occupation in Southeast Brazil has resulted in climatic disturbances and environmental contamination by air pollutants, threatening the Atlantic forest remnants that still exist in that region. Based on previous results, we assumed that pioneer tree species are potentially more tolerant against environmental oxidative stress than non-pioneer tree species from that Brazilian biome. We also assumed that reactive oxygen species (ROS) are accumulated in higher proportions in leaves of non-pioneer trees, resulting in changes in the oxidant-antioxidant balance and in more severe oxidative damage at the cellular level than in the leaves of pioneer trees. We tested these hypotheses by establishing the relationship between oxidants (ROS), changes in key antioxidants (among enzymatic and non-enzymatic compounds) and in a lipid peroxidation derivative in their leaves, as well as between ROS accumulation and oscillations in environmental stressors, thus permitting to discuss comparatively for the first time the oxidant-antioxidant balance and the tolerance capacity of tree species of the Atlantic Forest in SE Brazil. We confirmed that the non-pioneer tree species accumulated higher amounts of superoxide and hydrogen peroxide in palisade parenchyma and epidermis, showing a less effective antioxidant metabolism than the pioneer species. However, the non-pioneer species showed differing capacities to compensate the oxidative stress in both years of study, which appeared to be associated with the level of ROS accumulation, which was evidently higher in 2015 than in 2016. We also applied exploratory multivariate statistics, which revealed that the oscillations in these biochemical leaf responses in both functional groups coincided with the oscillations in both climatic conditions and air pollutants, seemingly showing that they had acclimated to the stressful oxidative environment observed and may perpetuate in the disturbed forest remnants located in SE Brazil.
巴西东南部广泛的土地占用导致气候紊乱和空气污染物对环境的污染，威胁到该地区仍然存在的大西洋森林残余。基于先前的结果，我们假设先锋树种比来自巴西生物群落的非先锋树种更能潜在耐受环境氧化应激。我们还假设活性氧 (ROS) 在非先锋树种的叶片中以更高的比例积累，导致氧化还原平衡发生变化，细胞水平的氧化损伤比先锋树种的叶片更严重。我们通过建立氧化剂 (ROS) 与叶片中关键抗氧化剂（包括酶和非酶化合物）的变化以及脂质过氧化衍生物之间的关系来检验这些假设，以及 ROS 积累与环境胁迫因子波动之间的关系，从而首次比较讨论了巴西东南部大西洋森林树种的氧化还原平衡和耐受能力。我们证实，非先锋树种在栅栏组织和表皮中积累了更多的超氧阴离子和过氧化氢，表现出比先锋树种更差的抗氧化代谢能力。然而，在这两年的研究中，非先锋物种表现出不同的补偿氧化应激的能力，这似乎与 ROS 积累水平有关，2015 年的积累水平明显高于 2016 年。我们还应用了探索性多元统计分析，结果表明，这两个功能组叶片生化反应的波动与气候条件和空气污染物的波动相吻合，似乎表明它们已经适应了所观察到的应激性氧化环境，并可能在巴西东南部受干扰的森林残余中持续存在。
