title: Target site mutation and reduced translocation are present in a glyphosate-resistant Lolium multiflorum Lam. biotype from Spain.
abstract: The resistance mechanism of a glyphosate-resistant Lolium multiflorum Lam. biotype collected in Córdoba (Southern Spain) was examined. Resistance Factor values at three different growth stages ranged between 4.77 and 4.91. At 96 hours after treatment (HAT) the S biotype had accumulated seven times more shikimic acid than the R biotype. There were significant differences in translocation of (14)C-glyphosate between biotypes, i.e. at 96 HAT, the R biotype accumulated in the treated leaf more than 70% of the absorbed herbicide, in comparison with 59.21% of the S biotype; the R biotype translocated only 14.79% of the absorbed (14)C-glyphosate to roots, while in the S population this value was 24.79%. Visualization of (14)C-glyphosate by phosphor imaging showed a reduced distribution in the R biotype compared with the S. Glyphosate metabolism was not involved in the resistance mechanism due to both biotypes showing similar values of glyphosate at 96 HAT. Comparison of the EPSPS gene sequences between biotypes indicated that the R biotype has a proline 182 to serine amino acid substitution. In short, the resistance mechanism of the L. multiflorum Lam. biotype is due to an impaired translocation of the herbicide and an altered target site.
authors: Department of Agricultural Chemistry and Edaphology, University of Córdoba, E-14071 Córdoba, Spain. z82gotof@uco.es
authors: Fidel
authors: F
authors: González-Torralva
authors: Javier
authors: J
authors: Gil-Humanes
authors: Francisco
authors: F
authors: Barro
authors: Ivo
authors: I
authors: Brants
authors: Rafael
authors: R
authors: De Prado
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000737:chemistry / Q000235:genetics*; D000222:Adaptation, Physiological / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D001692:Biological Transport; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006540:Herbicides / Q000494:pharmacology*; D008129:Lolium / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D018515:Plant Leaves / Q000378:metabolism*; D011392:Proline / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D012765:Shikimic Acid / Q000378:metabolism; D013030:Spain; D013045:Species Specificity; D013312:Stress, Physiological / Q000235:genetics; D000097797:Glyphosate
chemical_list: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D005998:Glycine; D006540:Herbicides; D011392:Proline; D012694:Serine; D012765:Shikimic Acid; D000097797:Glyphosate