Cytogenetic and microtubule array effects of the zineb-containing commercial fungicide formulation Azzurro® on meristematic root cells of Allium cepa L.

Zineb [ethylene bis(dithiocarbamate) zinc] is a widely employed foliar fungicide for agricultural and industrial applications. Allium cepa L. is a reliable model for the assessment of xenobiotic genotoxicity and cytotoxicity. We evaluated the effects of the zineb-containing commercial formulation Azzurro® (70% zineb) in cell cycle stages of the meristem root cells of A. cepa. The mitotic index (MI), chromosomal aberrations at anaphase/telophase (CAs), micronuclei (MN), and abnormalities in immunodetected microtubule structures, e.g., preprophasic band (PPB), mitotic spindle (MS), and phragmoplast (Phrag), were used as end-points. Azzurro® (1 and 10 μg/ml) induced a significant increase in the frequency of CAs (P < 0.05), and the higher concentration inhibited the MI (P < 0.05) compared to control values. The frequency of MN did not differ from control values at any concentration. Treatment with 1 μg/ml Azzurro® induced a significant increase in the frequency of abnormal PPB (P < 0.01), MS (P < 0.001), and Phrag (P < 0.01) and, at 10 μg/ml, enhancements in the frequencies of abnormal MS (P < 0.05) and Phrag (P < 0.05) were seen. A tubulin immunodetection assay showed that exposure to Azzurro® interferes with normal assembly of microtubule structures during mitosis.

► Azurro induces chromosome aberrations in agreement with microtubular damage.
► Azurro promotes the inhibition of the mitotic index.
► The exposure of Azurro does not induce micronuclei formation.