Dose-Dependent Physiological, Genotoxic and Histological Effects of Ethanolamine in A Plant Bioindicator System (Allium cepa L.)

Ethanolamines are widely used chemical compounds in industrial applications and can be released into the environment through wastewater and soil. However, studies investigating their physiological, genotoxic, and anatomical effects on plants are very limited, and no comprehensive evaluation using the Allium cepa model has been reported. In this study, the toxic effects of ethanolamine (EA) on Allium cepa were investigated for the first time using physiological, cytogenetic, and anatomical parameters. The EC₅₀ value was defined as the concentration causing a 50% reduction in mean root length compared to the control group and was calculated as 50 mg/L based on root growth inhibition. Accordingly, onion bulbs were exposed to 25 mg/L, 50 mg/L (EC₅₀), and 100 mg/L ethanolamine for 72 hours. Ethanolamine exposure caused statistically significant, dose-dependent decreases in root growth, biomass accumulation, and germination rate. Compared with the control group, germination decreased by 10% at 25 mg/L, 46.7% at 50 mg/L, and 56.7% at 100 mg/L. Cytogenetic analyses showed a significant increase in micronucleus frequency and a marked decrease in the mitotic index with increasing ethanolamine concentration. Various chromosomal abnormalities, including sticky and vagrant chromosomes, pole flattening, unequal chromatin distribution, fragments, and bridges, were also observed. Anatomical analyses revealed dose-dependent increases in epidermal cell damage, nuclear flattening, cortex cell wall thickening, vacuolization, and structural alterations in vascular tissues of the root meristem. In conclusion, ethanolamine induced clear dose-dependent phytotoxic, genotoxic, and anatomical damage in Allium cepa, providing a novel contribution to the limited literature on ethanolamine toxicity in plants.