Allium cepa tests: Exploring bleomycin induced cyto-genotoxicity and altered cell cycle kinetics in root tips meristematic cells

Bleomycin, commonly employed in treating Hodgkin’s lymphoma and testicular cancer, is associated with significant pulmonary toxicity. While various studies have assessed the toxic impact of chemotherapeutic agents on aquatic and terrestrial environments, limited data exist on bleomycin's effects, especially concerning higher plants. To address this gap, we utilized the Allium cepa assays, renowned for evaluating chemical and biochemical agents' toxic effects, to investigate bleomycin's impact on the terrestrial ecosystem. Our study aimed to assess bleomycin's cyto-genotoxic effects on A. cepa root tip cells at minimal concentrations (10–40 μg mL⁻¹) and varied exposure durations (2, 4, 6, and 24 h). Analysis of nuclear and mitotic abnormalities in bleomycin-treated A. cepa root tip cells, alongside an acridine orange-ethidium bromide double staining assay, illuminated its influence on cell viability. Additionally, agarose gel electrophoresis determined the drug's potential for DNA degradation, unveiling the underlying mechanisms of cyto-genotoxicity. Results also demonstrated a decline in the mitotic index with increased bleomycin concentrations and exposure time, elevated frequencies of various cyto-genotoxic abnormalities, including sticky chromosomes, chromatid breaks, laggards, bridges, polar deviations, nuclear lesions, and hyperchromasia. The study indicated the potential risks of bleomycin even at low concentrations and brief exposures, highlighting its severe adverse effects on genetic material of plant, potentially contributing to cell death. Consequently, this investigation unveils bleomycin's cyto-genotoxic effects on higher plant system, underscoring its threat to terrestrial ecosystems, particularly upon chronic and unmonitored exposure.