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A hydroponics experiment using hyperaccumulator Thlaspi caerulescens (alpine pennycress) and non-specific accumulator Raphanus sativus (common radish) was conducted to investigate the short-term effect of increasing Cd concentrations (0, 25, 50, 75, 100 μM) on metal uptake, chlorophyll content, antioxidative enzymes, and apoplastic bypass flow. As expected, T. caerulescens generally showed better resistance to metal stress, which was reflected by higher Cd accumulation within plant tissues with no signs of chlorosis, or wilt. Glutathione reductase (GR) and superoxide dismutase (SOD) activities in fresh leaves were monitored as the plant metal-detoxifying response. In general, both plant species exhibited an increase trend of GR activity before declining at 100 μM likely due to excessive levels of phytotoxic Cd. SOD activity exhibited almost a similar variation pattern to GR and decreased also at 100 μM Cd. For both plant species, fluorescent PTS uptake (8-hydroxy-l,3,6-pyrenetrisulphonic acid) increased significantly with metal level in exposure solutions indicating that Cd has a comparable effect to drought or salinity in terms of the gain of relative importance in apoplastic bypass transport under such stress conditions. [ABSTRACT FROM AUTHOR]

This article discusses a study which compared the performance of Thlaspi caerulescens to accumulate heavy metals (HM) with that of three nonaccumulator plants. The researchers exposed the plants to the separately dissolved HM salts for seven days at a wide range of increasing concentrations. They combined chemical, physiological, and ecotoxicological assessments. The researchers concluded that excessive concentrations of HM affected plant growth, photosynthesis, and phytoaccumulation efficiency.