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Molecular distribution and toxicity assessment of yttrium in Elodea canadensis
Aquatic plants are known to accumulate and bioconcentrate metals. In the present study, Elodea canadensis was subjected to different doses of yttrium (Y; ranging from 0 to 200 μM) for 7 d, and analysed for subcellular distribution and molecular localization of Y, accumulation of mineral nutrients in leaf tissue, changes in photosynthetic pigments, oxidative stress, and leaf and organelle ultrastructure. Leaf fractionation by differential centrifugation indicated that 68 %–76 % of Y was accumulated in the cell wall, and this level was higher in cellulose and pectin than in other biomacromolecules. At all Y concentrations, the Ca, Mg, and Mn levels decreased in E. canadensis, whereas P levels increased; Fe and K levels increased initially and then declined. A remarkable concentration-dependent reduction in photosynthetic pigments was observed. The components of the antioxidant system exhibited varied responses to Y treatments, whereas reactive oxygen species and malondialdehyde exhibited sharp increases at all Y concentrations. In addition, morphological symptoms of aging, such as chlorosis and damage to chloroplasts and mitochondria, were induced even at the lowest Y concentration. The results revealed that exogenous Y is widely available to this aquatic plant, which may have negative effects on aquatic organisms.
MF17142 Accepted 07 September 2017
© CSIRO 2017