Cytogenetic and genotoxic effects of penoxsulam on Allium cepa L. root meristem cells

Penoxsulamais a new post-emergenceaherbicide used on rice crops for annual grasses, broadleaf weeds, and sedges control, either grown through transplanting or direct dry or direct seeding methods of planting. Penoxsulam acts through inhibition of the Acetolactate Synthase (ALS), controlling cell division cessation and subsequent growth processes in plants. In this study, Allium ana-telophase and comet assay were used to examine the cyto-genotoxic effects of herbicide Penoxsulam on Allium cepa roots. Allium cepa bulbs were exposed to ½xEC50, EC50 and 2xEC50 concentrations of Penoxsulam, distilledawater (negativeacontrol) and Methyl methanesulfonate (MMS-10 ppm, positive control) for 24, 48, 72 and 96 h. Penoxsulam showed a cytotoxic effect by reducing root growth and mitotic index (MI), a genotoxic effect because it statistically increased chromosome aberrations (CAs, anaphase bridge, chromosomal laggards, disturbed anaphase-telophase, polyploidy and stickiness) and DNA damage as compared to control. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was also used for quantitative analysis of Penoxsulam in A. cepa root meristem cells. Further molecular toxicological evaluations associated in the cyto-genotoxicity of penoxsulam on plants are needed to confirm these results. Keywords: Penoxsulam, Allium test, Comet Assay, Chromosome Aberrations