Esomeprazole Magnesium Trihydrate Impairs Maize Root Meristem Activity and Chromosome Stability: Cytogenetic Evidence of Pharmaceutical-Induced Plant Stress

Pharmaceutical residues, including proton pump inhibitors such as esomeprazole, are increasingly detected in soil and water, yet their effects on crop root development, meristematic activity, and genome stability remain poorly characterized. In particular, no data exist on the cytogenetic impact of esomeprazole magnesium trihydrate (EMT) in plant test systems. This study therefore evaluated the cytotoxic and genotoxic effects of EMT on maize root meristem cells using seed soaking and cytogenetic analysis. Healthy maize seeds were germinated, and actively growing roots were exposed to EMT at 20, 40, and 60 mg/L for 48 h, with untreated roots serving as the control. Root tips were processed using Carnoy’s fixative and safranin staining, and mitotic phases and chromosomal aberrations were scored microscopically. Germination occurred across all treatments, but higher EMT concentrations caused progressive root growth inhibition and visible root-tip abnormalities. Control cells showed normal mitotic stages, whereas treated roots displayed a range of chromosomal abnormalities, including bridges, fragments, stickiness, and laggards. The total aberration frequency rose sharply from 0.5% in the control to 4.0%, 8.9%, and 20.4% at 20, 40, and 60 mg/L, respectively, while the mitotic index declined from 14.3% to 13.1%, 9.7%, and 6.3%. These concentration-dependent responses indicate that EMT suppresses meristematic cell division and disrupts chromosome organization and segregation in maize root tips. These findings demonstrate a clear concentration-dependent cytotoxic and genotoxic effect of EMT on maize root cells and provide the first baseline data on the potential risk of this pharmaceutical residue to crop plants. The study highlights maize root meristems as a sensitive plant bioassay system for evaluating pharmaceutical-induced stress in agricultural environments.