title: Pool of resistance mechanisms to glyphosate in Digitaria insularis.
abstract: Digitaria insularis  biotypes resistant to glyphosate have been detected in Brazil. Studies were carried out in controlled conditions to determine the role of absorption, translocation, metabolism, and gene mutation as mechanisms of glyphosate resistance in D. insularis. The susceptible biotype absorbed at least 12% more (14)C-glyphosate up to 48 h after treatment (HAT) than resistant biotypes. High differential (14)C-glyphosate translocation was observed at 12 HAT, so that >70% of the absorbed herbicide remained in the treated leaf in resistant biotypes, whereas 42% remained in the susceptible biotype at 96 HAT. Glyphosate was degraded to aminomethylphosphonic acid (AMPA), glyoxylate, and sarcosine by >90% in resistant biotypes, whereas a small amount of herbicide (up to 11%) was degraded by the susceptible biotype up to 168 HAT. Two amino acid changes were found at positions 182 and 310 in EPSPS, consisting of a proline to threonine and a tyrosine to cysteine substitution, respectively, in resistant biotypes. Therefore, absorption, translocation, metabolism, and gene mutation play an important role in the D. insularis glyphosate resistance.
authors.affiliation: Department of Applied Biology to Agropecuary, São Paulo State University, Jaboticabal, Brazil. agrolbcarvalho@gmail.com
authors.forename: Leonardo Bianco
authors.initials: LB
authors.lastname: de Carvalho
authors.forename: Pedro Luis da Costa Aguiar
authors.initials: PL
authors.lastname: Alves
authors.forename: Fidel
authors.initials: F
authors.lastname: González-Torralva
authors.forename: Hugo Enrique
authors.initials: HE
authors.lastname: Cruz-Hipolito
authors.forename: Antonia María
authors.initials: AM
authors.lastname: Rojano-Delgado
authors.forename: Rafael
authors.initials: R
authors.lastname: De Prado
authors.forename: Javier
authors.initials: J
authors.lastname: Gil-Humanes
authors.forename: Francisco
authors.initials: F
authors.lastname: Barro
authors.forename: María Dolores Luque
authors.initials: MD
authors.lastname: de Castro
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000235:genetics / Q000378:metabolism; D001938:Brazil; D031746:Digitaria / Q000187:drug effects* / Q000502:physiology*; D005998:Glycine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D006038:Glyoxylates / Q000378:metabolism; D053209:Herbicide Resistance; D006540:Herbicides / Q000494:pharmacology; D007555:Isoxazoles; D009154:Mutation; D063065:Organophosphonates / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D012521:Sarcosine / Q000378:metabolism; D012765:Shikimic Acid / Q000032:analysis / Q000378:metabolism; D013777:Tetrazoles; D000097797:Glyphosate
chemical_list: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D005998:Glycine; D006038:Glyoxylates; D006540:Herbicides; D007555:Isoxazoles; D063065:Organophosphonates; D012521:Sarcosine; D012765:Shikimic Acid; D013777:Tetrazoles; D000097797:Glyphosate; C418233:2-amino-3-(3-hydrox-5(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl)propionic acid; C031150:glyoxylic acid