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| Physiological adaptations to cadmium stresses and cadmium accumulation in lettuce |
| Received:January 05, 2018 |
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| KeyWord:lettuce;cadmium;physiological adaptations;accumulation and distribution;enrichment coefficients |
| Author Name | Affiliation | E-mail | | JIA Yue-hui | New Technological Key Laboratory of Agricultural Application in Beijing/Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China | | | HAN Ying-yan | New Technological Key Laboratory of Agricultural Application in Beijing/Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China | | | LIU Jie | New Technological Key Laboratory of Agricultural Application in Beijing/Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China | jiel@bua.edu.cn | | GAO Fan | New Technological Key Laboratory of Agricultural Application in Beijing/Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China | | | LIANG Qiong | New Technological Key Laboratory of Agricultural Application in Beijing/Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China | | | YU Ping | New Technological Key Laboratory of Agricultural Application in Beijing/Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China | | | LIU Chao-jie | New Technological Key Laboratory of Agricultural Application in Beijing/Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China | | | ZHANG Xin | New Technological Key Laboratory of Agricultural Application in Beijing/Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China | | | SU Bo-wei | New Technological Key Laboratory of Agricultural Application in Beijing/Plant Science and Technology College, Beijing University of Agriculture, Beijing 102206, China | |
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| Abstract: |
| Cadmium(Cd)pollution is a major environmental factor limiting crop growth. Lettuce is an important vegetable for human consumption and the physiological responses of lettuce to Cd stress are not well understood. In the present research, the effects of Cd stresses on lettuce growth were tested using seed germination and substrate culture experiments. The results showed that Cd stress significantly reduced the germination potential of lettuce seeds; the seed germination rate of lettuce was significantly inhibited by Cd stress, except in the 1 mg·L-1 Cd treatment. Lettuce biomass(fresh and dry weight)was significantly increased in the 50 mg·L-1 and 100 mg·L-1 Cd treatments, while Cd stress had no significant effect on the root/shoot ratio. In contrast to 10~200 mg·L-1 Cd, with 5 mg·L-1 Cd the concentrations of total chlorophyll, chlorophyll-a and chlorophyll-b were significantly higher than that of the control. Malondialdehyde(MDA)concentration was markedly increased with 5 mg·L-1 Cd and was unchanged with further increases of Cd stress, except for a significant decrease with 20 mg·L-1 Cd. Superoxide dismutase(SOD)activity decreased significantly and catalase(CAD)activity increased after inhibition with the increase of Cd stress, while peroxidase(POD)activity increased gradually. Cd concentrations in the underground and upper parts of lettuce increased with Cd concentration in the substrate, and the former was always higher than the latter for the same Cd concentration in the substrate. With increasing Cd concentration in the substrate, Cd enrichment coefficients decreased gradually in the upper parts of lettuce and decreased after an initial increase in the underground parts of lettuce, while Cd transport coefficients always decreased. Subcellular Cd concentrations in the underground parts of lettuce increased exponentially with increasing Cd concentration in substrate and increased linearly in the upper parts, while the former was always higher than the latter. Subcellular Cd distributions occurred in the following sequence:cell wall > soluble part > organelle in the underground parts, and cell wall and soluble part > organelle in the upper parts. Therefore, retention in the underground part(root system)and immobilization of the cell wall are important for adaptation to Cd stresses in lettuce. |
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