Thioarsenate toxicity and tolerance in the model system Arabidopsis thaliana

Titelangaben

Planer-Friedrich, Britta ; Kühnlenz, Tanja ; Halder, Dipti ; Lohmayer, Regina ; Wilson, Nathaniel ; Rafferty, Colleen ; Clemens, Stephan:
Thioarsenate toxicity and tolerance in the model system Arabidopsis thaliana.
In: Environmental Science & Technology. Bd. 51 (2017) Heft 12 . - S. 7187-7196.
ISSN 0013-936X
DOI: https://doi.org/10.1021/acs.est.6b06028

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Abstract

Thioarsenates form from arsenite under sulfate-reducing conditions, e.g. in rice paddy soils, and are structural analogues to arsenate. Even though rice is one of the most important sources of human arsenic (As) intake, nothing is published about uptake, toxicity, or tolerance of thioarsenates in plants. Experiments using the model system Arabidopsis thaliana showed that monothioarsenate is less toxic than arsenite, but more toxic than arsenate at concentrations \textgreater= 25 µM As, reflected in stronger seedlings growth inhibition on agar plates. Despite higher toxicity, total As accumulation in roots was lower upon exposure to monothioarsenate compared to arsenate and a higher root efflux was confirmed. Root-shoot translocation was higher for monothioarsenate than for arsenate. Compared to the wild type (Col-0), both arsenate and monothioarsenate induced higher toxicity in phytochelatin (PC)-deficient mutants (cad1-3) as well as in glutathione biosynthesis (cad2) and PC transport (abcc12) mutants demonstrating the important role of the PC pathway not only for arsenate, but also for monothioarsenate detoxification. In Col-0, monothioarsenate induced relatively higher accumulation of PCs than arsenate. The observed differences in plant uptake, toxicity, and tolerance of thio- vs. oxyarsenate show that studying the effects of As on plants should include experiments with thiolated As species.