title: Target-site mutation associated with glufosinate resistance in Italian ryegrass (Lolium perenne L. ssp. multiflorum).
abstract: BACKGROUND
  Studies were conducted to elucidate the mechanism of glufosinate resistance in an Italian ryegrass population.
  
  
  RESULTS
  Glufosinate rates required to reduce growth by 50% (GR(50)) were 0.15 and 0.18 kg AI ha(-1) for two susceptible populations C1 and C2 respectively, and 0.45 kg AI ha(-1) for the resistant population MG, resulting in a resistance index of 2.8. Ammonia accumulation after glufosinate treatment was on average 1.5 times less for the resistant population than for the susceptible populations. The glufosinate concentrations (µM) required to reduce the glutamine synthetase (GS) enzyme activity by 50% (I(50)) were 31 and 137 for C1 and C2 respectively, and 2432 for the resistant population MG. One amino acid substitution in the plastidic GS2 gene, aspartic acid for asparagine at position 171, was identified in the resistant population.
  
  
  CONCLUSIONS
  This is the first report of glufosinate resistance in a weed species that involves an altered target site.
authors.affiliation: Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Wilson V
authors.initials: WV
authors.lastname: Avila-Garcia
authors.forename: Elena
authors.initials: E
authors.lastname: Sanchez-Olguin
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Hulting
authors.forename: Carol
authors.initials: C
authors.lastname: Mallory-Smith
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000613:Aminobutyrates / Q000494:pharmacology*; D000641:Ammonia / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D053209:Herbicide Resistance; D006540:Herbicides / Q000494:pharmacology*; D008129:Lolium / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D000613:Aminobutyrates; D006540:Herbicides; D010940:Plant Proteins; C003121:phosphinothricin; D000641:Ammonia; D005974:Glutamate-Ammonia Ligase