期刊
JOURNAL OF EXPERIMENTAL BOTANY
卷 65, 期 17, 页码 4931-4942出版社
OXFORD UNIV PRESS
DOI: 10.1093/jxb/eru251
关键词
Acclimation; heavy-metal toxicity; membrane potential; Nicotiana tabacum; stomatal conductance; transporter; vacuole
资金
- Future and Emerging Technologies (FET) programme within 7th Framework Programme for Research of European Commission, under FET-Open [293431]
Evidence suggests that heavy-metal tolerance can be induced in plants following pre-treatment with non-toxic metal concentrations, but the results are still controversial. In the present study, tobacco plants were exposed to increasing Zn2+ concentrations (up to 250 and/or 500 mu M ZnSO4) with or without a 1-week acclimation period with 30 mu M ZnSO4. Elevated Zn2+ was highly toxic for plants, and after 3 weeks of treatments there was a marked (>= 50%) decline in plant growth in non-acclimated plants. Plant acclimation, on the other hand, increased plant dry mass and leaf area up to 1.6-fold compared with non-acclimated ones. In non-acclimated plants, the addition of 250 mu M ZnSO4 led to transient membrane depolarization and stomatal closure within 24 h from the addition of the stress; by contrast, the acclimation process was associated with an improved stomatal regulation and a superior ability to maintain a negative root membrane potential, with values on average 37% more negative compared with non-acclimated plants. The different response at the plasma-membrane level between acclimated and non-acclimated plants was associated with an enhanced vacuolar Zn2+ sequestration and up to 2-fold higher expression of the tobacco orthologue of the Arabidopsis thaliana MTP1 gene. Thus, the acclimation process elicited specific detoxification mechanisms in roots that enhanced Zn2+ compartmentalization in vacuoles, thereby improving root membrane functionality and stomatal regulation in leaves following elevated Zn2+ stress.
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