Genotoxicity of hormoban and seven other pesticides to onion root tip meristematic cells

Abstract

Plants are direct recipients of agro-toxics and therefore important materials for assessing environmental chemicals for genotoxicity. Three doses, representing ¼, ½ and EC50 of hormoban, storm killer, villa, fungi-nil, bexadust, aphicide, karbadust and basagran were assessed for cytotoxic and genotoxic effects to onion root tip cells in the root tip chromosome aberration assay after 24 h exposure. Cytotoxicity was inferred when the Mitotic index (dividing cells/1000 scored) of treated cells
was £ ½ negative control. All the pesticides were toxic. Genotoxicity was measured by analyzing 30 to 100 anaphase-telophase cells per dose of chemical for, chromosome fragments, bridges, vagrant chromosome, c-anaphase, multipolarity and stick chromosomes and comparing the percentage of aberrant cells at each dose with that of the negative control using the Chi-squared test. With the exception of basagran, the pesticides were genotoxic (P < 0.05). The C-anaphase and Stick chromosomes types of aberrations predominated which was evidence of the action of the pesticides on the mitotic spindle and the coiling of chromosomes during anaphase to telophase.