Cytogenotoxic Effects of Fluopyram in Allium cepa Root Cells Involving Microtubule Disruption

Fluopyram is a next-generation fungicide widely used in agriculture; however, its persistence in soils and mobility toward aquatic systems have raised concerns regarding potential ecotoxicological risks. This study evaluated the cytogenotoxic effects of a commercial fluopyram-based pesticide formulation on Allium cepa root meristem cells. Bulbs were exposed to four concentrations based on agricultural application rates: three times the recommended field dose (3 × FD; 5.00 mg mL^-1), the field dose (FD; 1.67 mg mL^-1), half the field dose (0.5 × FD; 0.835 mg mL^-1), and one-tenth the field dose (0.1 × FD; 0.17 mg mL^-1). Endpoints assessed included lipid peroxidation, cell viability, cytogenetic alterations, and DNA damage. No evidence of oxidative stress was detected. Nevertheless, the fluopyram-based formulation induced significant chromosomal aberrations and nuclear abnormalities at all tested concentrations, indicating pronounced genotoxic potential. The comet assay revealed a low frequency of DNA strand breaks, suggesting an aneugenic mode of action likely associated with mitotic spindle disruption rather than clastogenic damage. Mitotic analysis showed an accumulation of cells in prophase, reinforcing the interpretation of chromosome missegregation. In silico docking analyses further demonstrated strong interactions between fluopyram ions and tubulin, providing mechanistic support for spindle-associated aneugenicity. Overall, these findings highlight the cytogenotoxic risks associated with fluopyram-based pesticides and reinforce the importance of environmental monitoring to protect nontarget organisms.