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| Effects of Uranium Stress on Growth and Antioxidant System of Different Bryophytes |
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| DOI：10.16768/j.issn.1004-874X.2020.08.009 |
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| Abstract: |
| 【Objective】The study aimed to explore the characteristics of uranium accumulation and response mechanism of antioxidant enzyme system in bryophytes【Method】The solution culture method was used in this experiment. The plants of three species of bryophytes〔Hypnum plumaeforme, Hypnum cupressiforme L.ex Hedw. var. cupressiforme, Racomitrium canescens（Hedw.）Brid〕were treated with different concentrations of uranium（0, 5, 10, 15, 20 μmol/L）for 72 h, then the growth statuses of bryophytes were observed. The contents of uranium accumulation, soluble protein,
free proline（Pro）and malondialdehyde（MDA）in bryophytes were measured, and the activities of peroxidase（POD）, superoxide dismutase（SOD）and catalase（CAT）were determined.【Result】Uranium had toxic effect on the stems and leaves of bryophytes, showing that the stems and leaves turned yellow and black and shrank in different degrees, but it had no significant effect on their rhizoids. Among the three bryophytes, H. cupressiforme L.ex Hedw.var.cupressiforme had the strongest ability to accumulate uranium, reaching 3 440.67 mg/kg（DW）at uranium concentration of 25 μmol/L, with the BCF of 0.43. The accumulations of soluble protein and proline in three bryophytes were promoted by low and medium concentrations of uranium stress（5-10 μmol/L）, while they were significantly damaged by high concentration uranium stress（15-20 μmol/L）. MDA contents in three bryophytes increased significantly with the increase of uranium concentration. The activities of antioxidant enzymes in three bryophytes showed a positive response to low concentration（5-10 μmol/L）and a inhibitory effect to high concentration（15-20 μmol/L）.【Conclusion】Uranium stress has a significant effect on the growth and antioxidant enzyme system of bryophytes. Among them, the sensitivity of H. plumaeforme to uranium stress is higher than that of H. cupressiforme L.ex Hedw.var.cupressiforme and R. Canescens（Hedw.）Brid. H. cupressiforme L.ex Hedw.var.cupressiforme shows a certain ability of uranium tolerance and enrichment ability, and has the potential to be applied to the joint remediation of moss crust and hyperaccumulation plants in uranium mines. |
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