Guo Huihong, Wang Hui, Liu Qingqian, An Hailong, Liu Chao, Xia Xinli, Yin Weilun
College of Biological Science and Biotechnology, Beijing Forestry University, No. 35, Tsing Hua East Road, Haidian District, Beijing, 100083, China.
Environ Sci Pollut Res Int. 2017 Jan;24(1):500-508. doi: 10.1007/s11356-016-7620-2. Epub 2016 Oct 12.
Air pollution caused by particulate matter with aerodynamic diameters less than 2.5 μm (PM) is a serious environmental problem. Plants can improve air quality by removing PM from the atmosphere. However, direct evidence of PM absorption and assimilation into plants has not yet been found. In this study, we demonstrate that NH in PM was absorbed by poplar leaves in low and high PM treatment groups (namely, LPT and HPT). Then, N was subsequently transferred to other parts of the treated seedlings as shown by N tracing and simulated PM generation. N and total N contents were the highest in high pollution treatment (HPT), followed by that in low pollution treatment (LPT) and the control. Glutamate dehydrogenase (GDH) contributed more to NH assimilation than glutamine synthetase and glutamate synthase in the leaves of treated seedlings. GDH aminating activity was induced upon NH exposure whereas GDH deaminating activity was repressed in both LPT and HPT, suggesting that poplar seedlings can alleviate NH toxicity by enhancing NH assimilation. At the end of PM treatment period, the decreased amino acid content in the treated seedlings was attributed to the probably altered balance of amino acid metabolism. The decline in the net photosynthetic rate (Pn) was accompanied by the decrease in the stomatal conductance in poplar leaves with the extension of PM treatment time, indicating that stomatal limitation is a major reason for Pn reduction. This study may provide novel insights into the relationship between PM pollution and plants.
空气动力学直径小于2.5微米的颗粒物（PM）所造成的空气污染是一个严重的环境问题。植物可以通过从大气中去除PM来改善空气质量。然而，尚未发现PM被植物吸收并同化的直接证据。在本研究中，我们证明在低PM处理组和高PM处理组（即LPT和HPT）中，PM中的氮被杨树叶片吸收。然后，通过氮示踪和模拟PM生成表明，氮随后被转移到处理过的幼苗的其他部位。高污染处理（HPT）中的氮和总氮含量最高，其次是低污染处理（LPT）和对照组。在处理过的幼苗叶片中，谷氨酸脱氢酶（GDH）对氮同化的贡献大于谷氨酰胺合成酶和谷氨酸合酶。在LPT和HPT中，NH暴露诱导GDH氨基化活性，而GDH脱氨基活性受到抑制，这表明杨树幼苗可以通过增强氮同化来减轻NH毒性。在PM处理期结束时，处理过的幼苗中氨基酸含量的降低可能归因于氨基酸代谢平衡的改变。随着PM处理时间的延长，杨树叶片的净光合速率（Pn）下降伴随着气孔导度的降低，这表明气孔限制是Pn降低的主要原因。本研究可能为PM污染与植物之间的关系提供新的见解。
