Gomes Marcelo Pedrosa, Le Manac'h Sarah Gingras, Maccario Sophie, Labrecque Michel, Lucotte Marc, Juneau Philippe
Université du Québec à Montréal, Department of Biological Sciences, TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Succ. Centre-Ville, Montréal H3C 3P8, Québec, Canada; Université du Québec à Montréal, Institut des Sciences de l'environnement & GEOTOP, Succ. Centre-Ville, C.P. 8888, Montréal H3C 3P8, Québec, Canada.
Université du Québec à Montréal, Department of Biological Sciences, TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Succ. Centre-Ville, Montréal H3C 3P8, Québec, Canada.
Pestic Biochem Physiol. 2016 Jun;130:65-70. doi: 10.1016/j.pestbp.2015.11.010. Epub 2015 Nov 28.
We used a willow species (Salix miyabeana cultivar SX64) to examine the differential secondary-effects of glyphosate and aminomethylphosphonic acid (AMPA), the principal glyphosate by-product, on chlorophyll metabolism and photosynthesis. Willow plants were treated with different concentrations of glyphosate (equivalent to 0, 1.4, 2.1 and 2.8kgha(-1)) and AMPA (equivalent to 0, 0.28, 1.4 and 2.8kgha(-1)) and evaluations of pigment contents, chlorophyll fluorescence, and oxidative stress markers (hydrogen peroxide content and antioxidant enzyme activities) in leaves were performed after 12h of exposure. We observed that AMPA and glyphosate trigger different mechanisms leading to decreases in chlorophyll content and photosynthesis rates in willow plants. Both chemicals induced ROS accumulation in willow leaves although only glyphosate-induced oxidative damage through lipid peroxidation. By disturbing chlorophyll biosynthesis, AMPA induced decreases in chlorophyll contents, with consequent effects on photosynthesis. With glyphosate, ROS increases were higher than the ROS-sensitive threshold, provoking chlorophyll degradation (as seen by pheophytin accumulation) and invariable decreases in photosynthesis. Peroxide accumulation in both AMPA and glyphosate-treated plants was due to the inhibition of antioxidant enzyme activities. The different effects of glyphosate on chlorophyll contents and photosynthesis as described in the literature may be due to various glyphosate:AMPA ratios in those plants.
我们使用了一种柳树品种（柳属宫部柳栽培品种SX64）来研究草甘膦及其主要副产物氨甲基膦酸（AMPA）对叶绿素代谢和光合作用的不同次生效应。用不同浓度的草甘膦（相当于0、1.4、2.1和2.8 kg ha⁻¹）和AMPA（相当于0、0.28、1.4和2.8 kg ha⁻¹）处理柳树植株，暴露12小时后对叶片中的色素含量、叶绿素荧光和氧化应激标志物（过氧化氢含量和抗氧化酶活性）进行评估。我们观察到，AMPA和草甘膦引发了不同的机制，导致柳树植株中叶绿素含量和光合速率下降。两种化学物质均诱导柳树叶片中活性氧（ROS）积累，不过只有草甘膦通过脂质过氧化作用诱导氧化损伤。通过干扰叶绿素生物合成，AMPA导致叶绿素含量降低，进而影响光合作用。对于草甘膦，ROS的增加高于ROS敏感阈值，引发叶绿素降解（如通过脱镁叶绿素积累所见），光合作用持续下降。在AMPA和草甘膦处理的植株中过氧化物积累是由于抗氧化酶活性受到抑制。文献中描述的草甘膦对叶绿素含量和光合作用的不同影响可能是由于这些植株中草甘膦与AMPA的比例不同。
