title: EPSPS gene amplification in glyphosate-resistant Italian ryegrass (Lolium perenne ssp. multiflorum) from Arkansas.
abstract: BACKGROUND
  Resistance to glyphosate in weed species is a major challenge for the sustainability of glyphosate use in crop and non-crop systems. A glyphosate-resistant Italian ryegrass population has been identified in Arkansas. This research was conducted to elucidate its resistance mechanism.
  
  
  RESULTS
  The investigation was conducted on resistant and susceptible plants from a population in Desha County, Arkansas (Des03). The amounts of glyphosate that caused 50% overall visual injury were 7 to 13 times greater than those for susceptible plants from the same population. The EPSPS gene did not contain any point mutation that has previously been associated with resistance to glyphosate, nor were there any other mutations on the EPSPS gene unique to the Des03 resistant plants. The resistant plants had 6-fold higher basal EPSPS enzyme activities than the susceptible plants, but their I(50) values in response to glyphosate were similar. The resistant plants contained up to 25 more copies of EPSPS gene than the susceptible plants. The level of resistance to glyphosate correlated with increases in EPSPS enzyme activity and EPSPS copy number.
  
  
  CONCLUSIONS
  Increased EPSPS gene amplification and EPSPS enzyme activity confer resistance to glyphosate in the Des03 population. This is the first report of EPSPS gene amplification in glyphosate-resistant Italian ryegrass. Other resistance mechanism(s) may also be involved.
authors: Department of Crop, Soil and Environmental Sciences, University of Arkansas, Fayetteville, AR 72704, USA.
authors: Reiofeli A
authors: RA
authors: Salas
authors: Franck E
authors: FE
authors: Dayan
authors: Zhiqiang
authors: Z
authors: Pan
authors: Susan B
authors: SB
authors: Watson
authors: James W
authors: JW
authors: Dickson
authors: Robert C
authors: RC
authors: Scott
authors: Nilda R
authors: NR
authors: Burgos
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000235:genetics* / Q000378:metabolism; D001131:Arkansas; D005784:Gene Amplification; D018628:Gene Dosage; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D053209:Herbicide Resistance; D008129:Lolium / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D000097797:Glyphosate
chemical_list: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D005998:Glycine; D010940:Plant Proteins; D000097797:Glyphosate