Genotoxicity of Tetracycline as an Emerging Pollutant on Root Meristem Cells of Wheat (Triticum aestivum L.)

Increasing attention has been paid to antibiotic contamination as an increasingly serious environmental issue. Tetracycline has been widely used for decades in human and veterinary medicines, with incremental residues in the environment and adverse influences on living organisms. In the present study, the genetic toxicity of tetracycline was investigated using a bioassay method with wheat (Triticum aestivum L.) root-meristem cells at a concentration range of 0.25-300 mg L-1 and exposure times of 24, 48, and 72 h. The results indicated that tetracycline at lower concentrations (0.25-1 mg L-1) stimulated cell mitotic division, whereas at 50-300 mg L-1 concentration caused a concentration-related decrease in mitotic index (MI). The lower tetracycline concentrations induced a slight increase in the frequency of micronucleus (MN), chromosomal aberration (CA), and sister chromatid exchange (SCE) in wheat root tips. However, there were significant increases in these indices at higher concentrations in concentration and time-dependent manners, including the frequencies of MN (25-200 mg L-1), CA (10-200 mg L-1), and SCE (5-200 mg L-1), respectively. The inducement of MN, CA, and SCE decreased at 250 and 300 mg L-1 due to acute cell toxicity for all tested times. Comparatively, SCE was the most sensitive, followed by CA, with MN the least sensitive to the genotoxicity of tetracycline in wheat. These results imply that tetracycline may be genotoxic to plant cells, and exposure to tetracycline may pose a genotoxic risk to living organisms. The results also suggest that the wheat bioassay was efficient, simple, and reproducible in monitoring the genotoxicity of tetracycline in the environment. (C) 2010 Wiley Periodicals, Inc. Environ Toxicol 26: 417-423, 2011.