Scrutinizing the interaction between metribuzin with glutathione reductase 2 from Arabidopsis thaliana: insight into the molecular toxicity in agriculture.

As one of the triazine herbicides with widespread usage in agriculture, metribuzin exerted nonnegligible hazardous effects on plants via excessive accumulation of reactive oxygen species and destruction of antioxidant enzymes, but the underlying harmful mechanism of metribuzin-induced oxidative damage to plants has never been exploited. Here, Arabidopsis thaliana glutathione reductase 2 (AtGR2) was employed as the biomarker to evaluate the adverse impacts of metribuzin on plants. The fluorescence intensity of AtGR2 was decreased based on the static quenching mechanism with the prediction of a single binding site toward metribuzin, and the complex formation was presumed to be mainly impelled by hydrogen bonding and van der Waals forces from the negative ΔH and ΔS. In addition, the loosened and unfolded skeleton of AtGR2 along with the increased hydrophilicity around the tryptophan residues were investigated. Besides, the glutathione reductase activity of AtGR2 was also destroyed due to structural and conformational changes. At last, the severe inhibiting growth of Arabidopsis seedling roots was discovered under metribuzin exposure. Hence, the evaluation of the molecular interaction mechanism of AtGR2 with metribuzin will establish valuable assessments of the toxic effects of metribuzin on plants.