Li T Y, Xiong Z T
Department of Environmental Science, Wuhan University, Wuhan, Hubei 430072, China.
Ecotoxicol Environ Saf. 2004 Oct;59(2):174-9. doi: 10.1016/j.ecoenv.2003.11.007.
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.
在培养设施中采用水培法研究了镉对少根紫萍的毒性效应。镉处理（0.4 - 6.4微摩尔/升镉）促使少根紫萍在成熟前从母叶状体上释放出子叶状体，导致群体解体。少根紫萍植株群体解体的8小时和24小时半数效应浓度（EC50）值分别为0.12毫克/升和0.11毫克/升。相应地，最大允许浓度（MPC）分别为0.012毫克/升和0.011毫克/升（MPC = 10%×EC50）。这些值低于文献中报道的浮萍大多数此类生物标志物的值，表明少根紫萍的群体解体可作为植物毒性测试的敏感生物标志物。营养浓度（1/2、1/10、1/20、1/40和0倍霍格兰溶液浓度）和镉盐形式（氯化镉或硫酸镉）对群体解体没有显著影响。此外，不同植株克隆对镉胁迫的抗性差异显著。少根紫萍野生种群中约2%的群体对镉具有耐受性。这些结果表明，少根紫萍的群体解体可作为一种敏感、经济高效且有价值的生物标志物，用于评估镉和其他重金属的急性植物毒性。
