科研之友
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摘要
Even at trace levels, arsenic is of environmental and health concern due to its high toxicity. The xerohalophyte plant species Atriplex atacamensis grows on an arsenic-contaminated mining area in North Chile. Young seedlings that were grown from seeds collected from these plants were grown in a nutrient solution under controlled environmental conditions and were exposed for 14 and 28 days to 0, 100 or 1000 mu M arsenate. More than 75% of the plants that were exposed to the highest As dose survived until the end of the treatment. The seedling growth was reduced (100 mu M As) or inhibited (1000 mu M As) in the stress conditions, but the plants were able to efficiently close their stomata and perform osmotic adjustments to avoid secondary water stress. Arsenic accumulated up to 400 mu g g(-1) DW in the shoots and 3500 mu g g(-1) DW in the roots. Arsenate drastically impaired the P content and increased glycinebetaine content, although no arsenobetaine was found in the tissues. With the exception of arsenite and arsenate, no As-containing organic compound was detected. Arsenic was not excreted by the trichomes that were present at the leaf surface. Although an increase in the total level of non-protein thiols suggested that arsenite fixation on the sulfhydryl groups could occur in the stressed tissues, the majority of the soluble arsenic remained in its oxidized state As(V). Arsenate induced an increase in the free soluble polyamine concentrations in all of the organs, and it increased the proportion of spermidine and spermine and decreased the proportion of putrescine in the polyamine pool. Therefore, it is likely that these polycationic molecules may assist in arsenate sequestration in the stressed tissues, and A. atacamensis may represent a promising plant species that can be tested in field trials for its phytomanagement of As-contaminated sites in desert areas.
- 出版日期2011-12-15
