Cadmium-induced colony disintegration of duckweed (Lemna paucicostata Hegelm.) and as biomarker of phytotoxicity.
The toxic effect of cadmium on Lemna paucicostata was investigated with hydroponic culture in a culture facility. Cadmium treatment (0.4-6.4 micromol L(-1) Cd) induced L. paucicostata to release daughter fronds from the mother frond before maturity, resulting in colony disintegration. The 8-h and 24-h EC(50) values for colony disintegration in L. paucicostata plants were 0.12 and 0.11 mg L(-1), respectively. The maximum permissible concentrations (MPCs) were 0.012 and 0.011 mg L(-1) accordingly (MPC = 10% x EC(50)). These values were lower than the values of most of these biomarkers in duckweed reported in the literature, suggesting that colony disintegration in L. paucicostata may serve as a sensitive biomarker for the phytotoxicity test. Nutrient concentrations (1/2, 1/10, 1/20, 1/40, and 0-fold concentrations of Hoagland's solution) and Cd salt form (CdCl(2) or CdSO(4)) did not have a significant effect on colony disintegration. In addition, resistance to Cd stress differed significantly among clones of the plants. Approximately 2% of colonies in the wild population of L. paucicostata were tolerant of cadmium. These results indicate that colony disintegration of L. paucicostata could be used as a sensitive, cost-effective, and valuable biomarker to assess the acute phytotoxicity of cadmium and other heavy metals.
Department of Environmental Science, Wuhan University, Wuhan, Hubei 430072, China.
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D029064:Araceae / Q000187:drug effects* / Q000254:growth & development*; D002104:Cadmium / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D018527:Hydroponics; D020128:Inhibitory Concentration 50; D012100:Reproduction, Asexual / Q000187:drug effects; D013997:Time Factors
D002104:Cadmium