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Abstract
Reported cases of dinitroaniline resistance are credited to mutations within the α-tubulin protein: Leu-125-Met, Leu-136-Phe, Val-202-Phe, Thr-239-Ile, Met-268-Thr, Arg-243-Met/Lys. There are no reports of dinitroaniline resistance within tall fescue (Schedonorus arundinaceus) or other turfgrass species. The research goal was to find and identify a mutation in tall fescue that confers resistance to pendimethalin and possibly other dinitroaniline herbicides. Calli were generated and exposed to selection cycles on 3 μM pendimethalin medium. Putative tolerant genotypes were regenerated and hydroponically screened at 2 µM pendimethalin. Promising genotypes PR#39, PR#49, PR#74 were confirmed as tolerant. DNA extraction and sequence analysis failed to identify the presence of reported mutations. Metabolism as a possible mechanism of tolerance was tested using malathion, a P450 metabolic pathway inhibitor, to inhibit expression of pendimethalin tolerance. When PR#74 was treated with malathion prior to exposure to pendimethalin, tolerance was suppressed indicating the mode-of-action was associated with P450s herbicide metabolism.
INDEX WORDS: Tall fescue, Dinitroaniline, Herbicide resistance, Pre-emerge herbicide, Cool-season, Group 3, Mitotic inhibitor, Microtubule, Mutation, Target-site, Point-mutation, Hydroponics, Tissue culture, Callus induction, Plant regeneration, P450, Plant metabolism, Metabolic resistance, Malathion, DNA extraction, Dinitroaniline resistance, α-tubulin, Turfgrass, Pendimethalin, Herbicide metabolism
INDEX WORDS: Tall fescue, Dinitroaniline, Herbicide resistance, Pre-emerge herbicide, Cool-season, Group 3, Mitotic inhibitor, Microtubule, Mutation, Target-site, Point-mutation, Hydroponics, Tissue culture, Callus induction, Plant regeneration, P450, Plant metabolism, Metabolic resistance, Malathion, DNA extraction, Dinitroaniline resistance, α-tubulin, Turfgrass, Pendimethalin, Herbicide metabolism