CYTOTOXIC AND GENOTOXIC EFFECTS OF UV IRRADIATION ON ROOT MERISTEM CELLS OF ALLIUM CEPA L

The widespread use of ultraviolet radiation as a disinfectant necessitates an investigation into its possible harmful effects in living organisms. In the present study the effect of exposure to UVC radiation was studied using the Allium cepa assay. To determine the effect of UVC radiation, roots of four sets of A. cepa bulbs were irradiated with 254 nm UV radiation for durations of half, one, two and four hours, respectively. The cytotoxicity of UVC radiation was assessed by comparing the mitotic index of root meristem cells of exposed roots and unirradiated roots (control). Frequency of chromosomal aberrations in the dividing cells of the root meristem was taken as a measure of the genotoxicity of UVC radiation. The roots subjected to UVC exposure showed several types of chromosomal aberrations including sticky chromosomes, c-metaphase, vagrant chromosomes, irregular anaphase, multipolar anaphase, chromosomal bridges and laggards. The study clearly shows that exposure to UVC radiation for even a brief period of half an hour is cytotoxic and genotoxic.