Xiong Zhi-Ting, Liu Chao, Geng Bing
Department of Environmental Sciences, Wuhan University, Wuhan, Hubei 430079, People's Republic of China.
Ecotoxicol Environ Saf. 2006 Jul;64(3):273-80. doi: 10.1016/j.ecoenv.2006.02.003. Epub 2006 Apr 17.
Copper (Cu) from various anthropogenic and natural sources is one of the major heavy metal contaminants in the environment. To study Cu-induced nitrogen (N) metabolism damage in the popular vegetable Chinese cabbage (Brassica pekinensis Rupr.), aquatic culture experiments with this plant were performed. Two Cu levels (0.3 micromol/L (control) and 10.3 micromol/L) and two N levels (0.05- and 1-fold Hoagland's solution) were used for the aquatic culture experiments. The results demonstrated adverse effects of Cu on N metabolism and plant growth. Cu exposure elevated Cu concentration and decreased nitrate reductase (NR) activity in the roots and shoots and reduced total chlorophyll content. It also shortened root length and produced fewer leaves and lower plant biomass. However, Cu exposure increased total free amino acid content in the leaves. The results also demonstrated effects of N deficiency on N metabolism and plant growth. N deficiency increased the root/shoot ratio of biomass and the total free amino acid content and decreased the nitrate contents and NR activity in roots and leaves. In addition, there were interactive effects between Cu exposure and N level on plant biomass, root/shoot ratio, and chlorophyll and nitrate content in leaves. The results suggested that Cu toxicity to the plant was at least partly due to an influence on N metabolism.
来自各种人为和自然来源的铜（Cu）是环境中的主要重金属污染物之一。为了研究铜对常见蔬菜大白菜（Brassica pekinensis Rupr.）氮（N）代谢的损害，对该植物进行了水培实验。水培实验采用了两个铜水平（0.3微摩尔/升（对照）和10.3微摩尔/升）和两个氮水平（0.05倍和1倍的霍格兰溶液）。结果表明铜对氮代谢和植物生长有不利影响。暴露于铜会提高根和茎中的铜浓度，降低硝酸还原酶（NR）活性，并降低总叶绿素含量。它还会缩短根长，减少叶片数量并降低植物生物量。然而，暴露于铜会增加叶片中总游离氨基酸含量。结果还表明氮缺乏对氮代谢和植物生长的影响。氮缺乏会增加生物量的根/茎比和总游离氨基酸含量，并降低根和叶中的硝酸盐含量和NR活性。此外，铜暴露和氮水平对植物生物量、根/茎比以及叶片中的叶绿素和硝酸盐含量存在交互作用。结果表明，铜对植物的毒性至少部分是由于对氮代谢的影响。
