Testing of genotoxic effects of 2,4-dichlorophenoxyacetic acid (2,4-D) using multiple genetic assay systems of plants.

The mutagenic activity of 2,4-D was assessed utilising cytogenetic, chlorophyll mutation, specific-locus and pollen viability endpoints in Allium cepa and Oryza sativa. In the Allium root-tip assay onion bulbs with roots were treated with 25, 50, 75 or 100 ppm 2,4-D for 4 h and the frequency of aberrations was estimated. With an increase in concentration there was rise in frequency of aberrant cells. In the case of mutation assays, presoaked rice seeds were treated with 100, 200 or 300 ppm 2,4-D for 4 h and sown in the field. Mutation frequency was estimated on M1 plant, spike and M2 seedling basis. With increasing concentration, there was a concomitant increase in mutation frequency. Highly significant chlorophyll-deficient and waxy mutants besides sterile pollen were observed as compared to both positive (EMS) and negative controls (H2O). The study demonstrates that 2,4-D has genotoxic potential.