The mitigating effects of Tribulus terrestris extract on the cytotoxic, genotoxic, biochemical and phytotoxic effects of omethoate in roots of Allium cepa bulbs

The goal of this study was to investigate the protective potential of Tribulus terrestris L. extract (TTE) against omethoate induced toxicity in Allium cepa L. For this purpose, six groups of A. cepa bulbs were established. While tap water was applied to the control group, 25 µg/mL TTE, 50 µg/mL TTE, 5.7 mg/L omethoate, 5.7 mg/L omethoate + 25 µg/mL TTE, and 5.7 mg/L omethoate + 50 µg/mL TTE were applied to the experimental groups, respectively. Omethoate exposure decreased germination percentage, root elongation, weight gain, MI and chlorophyll a and chlorophyll b concentrations compared to control. MN, CAs, DNA tail percentage, proline and MDA levels as well as SOD and CAT activities of the omethoate treated group were higher than the control group. The abnormalities in the root meristem cells were epidermis cell damage, flattened nucleus, cortex cell damage, thickening of the cortex cell wall and transmission tissue thickening. TTE applied in mixture with omethoate alleviated all damages caused by omethoate. The protective effect of TTE was stronger at 50 µg/mL TTE than at 25 µg/mL TTE. TTE at a concentration of 50 µg/mL applied as a mixture with omethoate reduced MN frequency by 46% and DNA tail percentage by approximately 64% compared to omethoate alone. In the omethoate-treated group, the higher concentration of TTE decreased MDA content by 47.5%, proline levels by 38.5%, and SOD and CAT activities by 27.9% and 37.5%, respectively. The most dominant phenolic compounds in TTE were rutin, p-coumaric acid and 4_OH benzoic acid. This study offers a novel, multifaceted assessment demonstrating that TTE can mitigate omethoate-induced physiological, cytogenetic, biochemical, and anatomical damage in A. cepa, highlighting its potential as a plant-derived protective agent. In conclusion, our findings reveal that omethoate is toxic for A. cepa, and TTE mitigates this toxicity, a response related to its bioactive components.