Cadmium detoxification in Populus × canescens

Hui-Ping DAI, Chan-Juan SHAN, Genliang JIA, Chao LU, Tu-Xi YANG, An-Zhi WEI
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Cadmium is one of the most toxic heavy metals and affects all viable cells, even at low concentrations. It is introduced to agricultural soils mainly by phosphate fertilisers and causes many toxic symptoms in cells. Phytochelatins (PCs) are heavy metal-binding peptides that play an important role in sequestration and detoxification of heavy metals in plants. In this study, after a 12-week cultivation, the plants were treated with 5 CdSO47 H2O concentrations of 0 (control), 10, 30, 50, and 70 µM for 28 days. The effects of Cd on growth and on glutathione (GSH) and PC contents were investigated in the roots, bark, wood, and leaves of Populus × canescens. The accumulation of Cd increased with external Cd concentrations. The accumulation of Cd in roots was higher than that in bark, wood, and leaves. Dry mass production of different tissues decreased under Cd treatment, especially for leaves. In roots, bark, wood, and leaves, exposure to Cd caused an appreciable decline in GSH contents and an increase in PC synthesis proportional to Cd concentrations in the growth medium. At the same Cd concentration, PC production was higher in roots than in bark, wood, and leaves. Taken together, the majority of Cd was accumulated by Populus × canescens roots in the form of a Cd-PC complex.


Key words: Cadmium accumulation, cadmium tolerance, glutathione, phytochelatins

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