Analyzing the Genotoxic Effect of Heavy Metals Cr, Cu, Pb and Zn Using Allium cepa L.

This chapter aims to analyze the cytotoxic effects of chromium, copper, lead and zinc in A. cepa root tip squash mitotic cell divisions. Angiosperms are employed in monitoring studies because they are recognized as suitable genetic models for detecting heavy metal-based environmental mutagens. Allium cepa (onion) has been used to assess DNA damage such as chromosome aberrations and mitotic cycle abnormalities. The root tips were treated with three concentrations, viz. 5, 10 and 20 mg/100 ml of chromium, copper, lead and zinc at room temperature for 24 h. Mitotic indices and chromosomal abnormalities were computed. These heavy metals were found to cause chromosomal abnormalities such as Chromosome break, Chromosome bridge, C-mitosis, Vagrant, Delayed Anaphase and Vagrant, Chromosome Loss, Polyploidy and Chromosome Bridge, Chromosome Loss and Loculated Nucles, Stickiness, Multipolarity and Polyploid prophase along with the increasing doses. Chromium and lead were found to be more toxic than copper and zinc to the root meristem of A. cepa at a concentration of 20 mg/100 ml. The ranking of cytotoxic potentials was in the descending order: lead > chromium > copper > zinc.