Asp376Glu Mutation and Enhanced Metabolism Controlling the Resistance to ALS-Inhibiting Herbicides in Ixophorus unisetus (J. Presl) Schltdl from the Bajio, Mexico

A study was carried out to determine the ALS (acetolactate synthase)-inhibitor herbicide resistance in Mexican grass Ixophorus unisetus, a troublesome weed corn crops Mexico. First, confirmed field screening assays. Eight populations that survived nicosulfuron treatment at rate of 40 g ai ha−1 were labeled as putative-resistant. Dose–response trials demonstrated high eight (GR50 from 140.33 245.46 ha−1). The synergism malathion plus non-target-site (NTSR) mechanism based on cytochrome P450 (Cyt-P450) involved five I. unisetus. Molecular studies revealed single-nucleotide change occurs amino acid position 376 (from GAT GAG), which codifies Asp-376 Glu-376. This is first time Asp-376-Glu has been reported this species. Assays vitro and vivo unisetus cross-resistance flucarbazone, penoxsulam, bispyribac-Na, imazamox. No multiple found two resistant exposed different herbicides. Our results indicate lack good control over with inhibitors due target-site mutation NTSR mechanisms (Cyt-P450-mediated metabolism). strategy should be established fields continue controlling weed, including mechanical practices combination available pre- post-emergence