title: Amaranthus palmeri resistance and differential tolerance of Amaranthus palmeri and Amaranthus hybridus to ALS-inhibitor herbicides.
abstract: Suspected imazaquin-resistant accessions of Amaranthus palmeri were studied to determine the magnitude of resistance and cross-resistance to acetolactate synthase (ALS)-inhibiting herbicides and compare differential tolerance of A palmeri and Amaranthus hybridus to ALS inhibitors. Five of seven A palmeri accessions were resistant to imazaquin. The most imazaquin-resistant accession, accession 7, also showed 74, 39 and 117 times higher resistance than the susceptible biotype to chlorimuron, diclosulam and pyrithiobac, respectively. Resistance to imazaquin and cross-resistance to other ALS inhibitors in A palmeri was due to a less-sensitive ALS enzyme. A palmeri was 70 times more tolerant to imazaquin than A hybridus. A palmeri was also seven times more tolerant to pyrithiobac than A hybridus. Differences in ALS enzyme sensitivity could not fully account for the high tolerance of A palmeri to imazaquin compared to A hybridus. Both species were equally affected by chlorimuron and diclosulam.
authors.affiliation: Department of Crop, Soil, and Environmental Sciences, University of Arkansas, 1366W Altheimer Drive, Fayetteville, AR 72704, USA.
authors.forename: N R
authors.initials: NR
authors.lastname: Burgos
authors.forename: Y I
authors.initials: YI
authors.lastname: Kuk
authors.forename: R E
authors.initials: RE
authors.lastname: Talbert
mesh_terms: D000095:Acetolactate Synthase / Q000187:drug effects* / Q000378:metabolism; D001565:Benzoates / Q000494:pharmacology; D004351:Drug Resistance; D006540:Herbicides / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology; D019684:Magnoliopsida / Q000187:drug effects* / Q000201:enzymology; D011743:Pyrimidines / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D013045:Species Specificity; D013449:Sulfonamides / Q000494:pharmacology; D013453:Sulfonylurea Compounds / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology
chemical_list: D001565:Benzoates; D006540:Herbicides; D007093:Imidazoles; D011743:Pyrimidines; D011804:Quinolines; D013449:Sulfonamides; D013453:Sulfonylurea Compounds; D014230:Triazoles; C401888:pyrithiobac sodium; C415325:diclosulam; C057728:imazaquin; C112343:chlorimuron ethyl; D000095:Acetolactate Synthase