Systematic evaluation of three-generation diamide insecticides with glutathione reductase 2: molecular mechanisms and phytotoxic effects

As representative compounds spanning three generations of diamide insecticides, flubendiamide, chlorantraniliprole, and tetraniliprole have been extensively employed in agricultural practices. However, their widespread application induces oxidative stress in plants and underlying toxic mechanisms remain poorly understood. Given the important roles in oxidative stress, glutathione reductase 2 from Arabidopsis thaliana ( At GR2) was applied as a biomarker to evaluate the toxicological effects of diamide insecticides. Firstly, the root elongation in Arabidopsis seedlings was significantly inhibited and the At GR2 gene expression level was up-regulated under exposure of the diamide insecticides. Then the glutathione reductase activity of At GR2 was decreased with the increase concentration of these three insecticides, especially for flubendiamide with similar detrimental effects at much lower concentrations. Moreover, the binding affinity between flubendiamide and At GR2 was also stronger than that of chlorantraniliprole and tetraniliprole, which was conformed with molecular docking results. Additionally, much more evident effects on the structure of At GR2 under exposure of flubendiamide was detected through multispectral techniques compared to the other two insecticides. Hence this study systematically explored the binding mechanism of these three-generations of diamide insecticides with At GR2 at the molecular level, and further provided critical assessments of their phytotoxic effects on plant development and agricultural systems.