Phytotoxicity alleviation of imazethapyr to non-target plant wheat: active regulation between auxin and DIMBOA

Abstract Effectively controlling target organisms while reducing the adverse effects of pesticides on non-target organisms is a crucial scientific inquiry and challenge in pesticide ecotoxicology research. Here, we studied the alleviation of herbicide (R)-imazethapyr ((R)-IM) to non-target plant wheat by active regulation between auxin and secondary metabolite 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazine-3(4H)-one (DIMBOA). (R)-IM effortlessly disrupted the balance between wheat growth and defense, which reduced 32.4% auxin content in wheat leaves and induced 40.7% DIMBOA accumulation compared to the control group. Transcriptomic results indicate that restoration of the auxin level in plants promotes the up-regulation of growth-related genes, and increased accumulation of DIMBOA increases the expression of defense-related genes. Auxin and DIMBOA are in two divergent paths and alleviate herbicide stress on wheat primarily through effects on growth and defense, respectively. Additionally, as a common precursor of auxin and DIMBOA, indole adopted a combined growth and defense strategy in response to (R)-IM toxicity, i.e., restoring growth development and enhancing the defense system. Future regulation of auxin and DIMBOA levels in plants may be possible through appropriate methods, thus regulating the plant growth-defense balance under herbicide stress. Our insight into the interference mechanism of herbicides to the plant growth-defense system will facilitate the design of improved strategies for herbicide detoxification.