College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, PR China.
Ecotoxicol Environ Saf. 2021 Jan 15;208:111684. doi: 10.1016/j.ecoenv.2020.111684. Epub 2020 Nov 28.
Phytotoxicity and accumulation of Cu in mature and young leaves of submerged macrophyte Hydrilla verticillata (L.f.) Royle were investigated by analyzing the chlorophyll contents, chloroplast ultrastructure and leaf surface structure under different Cu treatments (0, 0.01, 0.05 and 0.1 f mg L). The results showed that 0.05 and 0.1 mg L Cu treatment decreased the contents of Chl a and Chl b, and caused damage on leaf surface structure and chloroplast ultrastructure compared with control (0 mg L Cu treatment). Higher concentration of Cu induced Chlorophyll decreases and the damages on the leaf surface structure and chloroplast ultrastructure were more pronounced in mature than in young leaves. It was observed that leaf Cu concentration increased almost linearly with exposure time and majority of the Cu accumulated in the cell walls. Among different cell wall fractions, the majority of Cu accumulated in cell walls was bound to the hemicellulose 1 and cellulose, followed by the pectin, hemicellulose 2. Mature leaves had significantly higher the concentrations of total Cu and bound-Cu in cell walls due to higher uronic acid content in their cell wall fractions (pectin, hemicellulose 1 and cellulose) than young leaves. Distinct cell wall composition might partially contribute to the different Cu toxicity and accumulation between mature and young leaves of submerged macrophyte H. verticillata. Our results show that mature leaves are more efficient in the uptake and accumulation of Cu than young leaves, which might explain why mature leaves sustain more severe damage.
采用不同浓度 Cu（0、0.01、0.05 和 0.1 f mg L）处理，研究沉水植物水蕴草（Hydrilla verticillata（L.f.）Royle）成熟叶和幼叶的叶绿素含量、叶绿体超微结构和叶片表面结构的变化，探讨其耐性和 Cu 积累特性。结果表明，与对照（0 f mg L Cu）相比，0.05 和 0.1 f mg L Cu 处理降低了 Chl a 和 Chl b 的含量，导致叶片表面结构和叶绿体超微结构受损。与幼叶相比，成熟叶中较高浓度的 Cu 导致叶绿素含量下降，对叶片表面结构和叶绿体超微结构的损伤更为明显。叶片 Cu 浓度随暴露时间呈近线性增加，且大部分 Cu 积累在细胞壁中。在细胞壁的不同细胞壁组分中，大部分 Cu 与半纤维素 1 和纤维素结合，其次是果胶和半纤维素 2。成熟叶片细胞壁中总 Cu 和结合态 Cu 的浓度明显高于幼叶，这是由于其细胞壁组分（果胶、半纤维素 1 和纤维素）中的酸性多糖含量较高。细胞壁组成的差异可能部分导致水蕴草成熟叶和幼叶对 Cu 的毒性和积累存在差异。研究结果表明，成熟叶片比幼叶更有效地吸收和积累 Cu，这可能解释了为什么成熟叶片受到更严重的损伤。
