Metabolomic analysis of Schoenoplectus juncoides reveals common markers of acetolactate synthase inhibition among paddy weeds.

Despite the increase in pressure for reducing the use of chemical pesticides in agriculture, herbicides remain one of the efficient tools for augmenting food production. Various herbicide-resistant weeds against most herbicidal modes of action (MoA) are emerging worldwide, and therefore, the necessity of developing herbicides with novel MoA is increasing. Toward this, rigid methods of determining MOA that can be applied for various weeds species are required. Despite the existence of weed species with resistance to acetolactate synthase (ALS) inhibitors, inhibition of ALS remains one of the most widely used herbicidal MoAs containing more than 50 commercial active ingredients. Here, we aimed to identify marker metabolites that are indicative of ALS inhibition. We performed non-targeted and targeted metabolomics using ALS inhibitor-treated Schoenoplectus juncoides. We identified internal metabolite markers for ALS inhibition, with excellent selectivity for ALS inhibitors and herbicides with different MOAs in various weed species. These markers will enable us to evaluate ALS inhibitory activity of chemicals in vivo in a wide variety of weed species.