title: Possible glyphosate tolerance mechanism in pitted morningglory (Ipomoea lacunosa L.).
abstract: Natural tolerance of Ipomoea lacunosa to glyphosate has made it problematic in the southeastern U.S. since the adoption of glyphosate-resistant crops. Experiments were conducted to determine (i) the variability in tolerance to glyphosate among accessions, (ii) if there is any correlation between metabolism of glyphosate to aminomethylphosponic acid (AMPA) or sarcosine and the level of tolerance, and (iii) the involvement of differential translocation in tolerance to glyphosate. Fourteen I. lacunosa accessions had GR50 values ranging from 58 to 151 grams of acid equivalent per hectare (ae/ha) glyphosate, a 2.6-fold variability in tolerance to glyphosate. There was no evidence of the most tolerant (MT) accession metabolizing glyphosate to AMPA more rapidly than the least tolerant (LT) accession. Metabolism to sarcosine was not found. (14)C-glyphosate absorption was similar in the two accessions. LT accession translocated more (14)C-glyphosate than MT accession at 24 and 48 h after treatment. Differential translocation partly explains glyphosate tolerance in MT accession.
authors.affiliation: Department of Plant and Soil Sciences, Mississippi State University , P.O. Box 9555, Mississippi State, Mississippi 39762, United States.
authors.forename: Daniela N
authors.initials: DN
authors.lastname: Ribeiro
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Nandula
authors.forename: Franck E
authors.initials: FE
authors.lastname: Dayan
authors.forename: Agnes M
authors.initials: AM
authors.lastname: Rimando
authors.forename: Stephen O
authors.initials: SO
authors.lastname: Duke
authors.forename: Krishna N
authors.initials: KN
authors.lastname: Reddy
authors.forename: David R
authors.initials: DR
authors.lastname: Shaw
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D053209:Herbicide Resistance; D006540:Herbicides / Q000494:pharmacology*; D027741:Ipomoea / Q000187:drug effects* / Q000378:metabolism; D007555:Isoxazoles; D063065:Organophosphonates / Q000378:metabolism; D013045:Species Specificity; D013777:Tetrazoles; D000097797:Glyphosate
chemical_list: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D004791:Enzyme Inhibitors; D005998:Glycine; D006540:Herbicides; D007555:Isoxazoles; D063065:Organophosphonates; D013777:Tetrazoles; D000097797:Glyphosate; C418233:2-amino-3-(3-hydrox-5(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl)propionic acid
keywords: 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS); Ipomoea lacunosa; absorption; glyphosate; herbicide resistance; metabolism; pitted morningglory; translocation