Abstract

The present study reports the potential genotoxic effects of a widely used insecticide, endosulfan (Endoin 35% EC), on root tip cells of onion (Allium cepa L.). Treatment of onion root tips at a concentration of 0.156 μg/L of endosulfan showed highest fluctuation of mitotic depression at various durations (0.38 to -181%) of exposure. The mitotic index decreased with the increase in the concentrations of endosulfan mostly at 48 h treatment. The maximum number of dividing cells (n) was observed to be 224 calculated as maximum MI value of 7.0 in lowest concentration (0.0078 μg/L) at 72 h. The abnormalities of common occurrence were unequal cytokinesis and karyokinesis and formation of binucleolated cells in many cases. Gradual decondensation or little condensed chromosomal arms were the common observations in abnormal metaphases and anaphases. The frequencies of all the mitotic abnormalities showed a good correlation with the concentration of the insecticide.

Key words: Allium cepa, endosulfan, mitotic index, aberrant cells, genotoxicity.