Determination of Pb genotoxic effects in Allium cepa root cells by fluorescent probe, microtubular immunofluorescence and comet assay

In order to further understand the toxic effects of Pb on root tip cells of Allium cepa var. agrogarum, root growth, Pb uptake, cell division, DNA damage and MT cytoskeleton were investigated. Fluorescence labeling; Carbol Fuchsin-staining; indirect immunofluorescent microscopy; comet assay. Pb ions entered A. cepa root meristem cells within hours of exposure. The mitotic index (MI) decreased progressively with increasing of Pb concentration. Chromosomal segregation and motility are inhibited, which is directly correlated with the disorganization of the corresponding MT arrays. Pb may interact with tubulin and hinder the polymerization process, resulting in defective mitotic spindles. Pb induced DNA damage in A. cepa root nuclei. Root tips of plants are the most sensitive organ to environmental stresses. Root apical meristems play a key role in the immediate reaction to stress factors by activating signal cascades to the other plant organs. The data presented above can be used as valuable and early markers in cellular changes induced by metals for the evaluation of metal contamination and can be used as early warning signals for general or particular stress.