Phytotoxicity of potassium antimony(III) oxide tartrate trihydrate in Allium cepa revealed through multilevel biological responses

Antimony is an increasingly widespread environmental metalloid capable of exerting significant toxic effects on biological systems. However, the mechanisms underlying its multi-faceted toxicity in plant cells remain incompletely understood. This study aimed to provide an integrated assessment of the physiological, cytogenetic, biochemical, and anatomical effects of potassium antimony (III) oxide tartrate trihydrate in Allium cepa L. root meristem cells. Root-based endpoints were evaluated following exposure to 20, 100, and 500 µg/L Sb for 72 h, whereas exposure was extended to 144 h to allow sufficient leaf development for chlorophyll analysis. Germination and growth parameters, mitotic index, micronucleus frequency, chromosomal abnormalities, DNA damage, malondialdehyde content, superoxide dismutase and catalase activities, chlorophyll contents, and anatomical alterations were evaluated. Antimony exposure significantly reduced germination, root length, weight gain, and mitotic index, while markedly increasing micronucleus and chromosomal abnormality frequencies. Comet assay revealed a reduction in head DNA from 96.9% to 66.5%, accompanied by an increase in tail DNA from 3.10% to 33.5%. Moreover, antimony exposure markedly enhanced lipid peroxidation and antioxidant enzyme activities, while substantially reducing chlorophyll a and chlorophyll b contents. Anatomical analyses demonstrated increases in epidermal cell damage, cortical cell wall thickening, and flattened nucleus. Collectively, these findings suggest that antimony suppresses cell division, disrupts genomic integrity, and induces structural tissue damage in A. cepa root meristem cells. This integrated assessment demonstrates the multilevel phytotoxic effects of potassium antimony(III) oxide tartrate trihydrate and provides a basis for future investigations of its toxicological mechanisms and ecotoxicological significance.