title: Target-site EPSPS Pro-106 mutations: sufficient to endow glyphosate resistance in polyploid Echinochloa colona?
abstract: BACKGROUND
  This study confirms and characterises glyphosate resistance in two polyploid Echinochloa colona populations from north-eastern Australia.
  
  
  RESULTS
  Glyphosate dose response revealed that the two resistant populations were marginally (up to twofold) resistant to glyphosate. Resistant plants did not differ in non-target-site foliar uptake and translocation of (14) C-glyphosate, but contained the known target-site 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) mutation Pro-106-Thr and/or Pro-106-Leu. Although plants carrying either a single or two EPSPS mutations were glyphosate resistant relative to the susceptible population, they were still controlled at the field rate of glyphosate (450 g a.e. ha(-1) ) when treated under warm conditions (25/20 °C). However, when treated in hot conditions (35/30 °C), most mutant resistant plants (68%) can survive the field rate, and an increase (2.5-fold) in glyphosate LD50 was found for both the R and S populations.
  
  
  CONCLUSIONS
  This study shows that one or two EPSPS Pro-106 mutations are insufficient to confer field-rate glyphosate resistance in polyploidy E. colona at mild temperatures. However, control of these mutant plants at the glyphosate field rate is poor at high temperatures, probably owing to reduced glyphosate efficacy. Therefore, glyphosate should be applied during relatively mild (warm) temperature periods in the summer growing season to improve E. colona control.
authors.affiliation: Australian Herbicide Resistance Initiative, School of Plant Biology, University of Western Australia, Western Australia, Australia.
authors.forename: Heping
authors.initials: H
authors.lastname: Han
authors.affiliation: Australian Herbicide Resistance Initiative, School of Plant Biology, University of Western Australia, Western Australia, Australia.
authors.forename: Qin
authors.initials: Q
authors.lastname: Yu
authors.affiliation: Queensland Department of Agriculture and Fisheries, Toowoomba, Australia.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Widderick
authors.affiliation: Australian Herbicide Resistance Initiative, School of Plant Biology, University of Western Australia, Western Australia, Australia.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Powles
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000037:antagonists & inhibitors / Q000235:genetics*; D001315:Australia; D031747:Echinochloa / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D053209:Herbicide Resistance; D006540:Herbicides / Q000494:pharmacology*; D009154:Mutation; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D011123:Polyploidy; D013696:Temperature; D000097797:Glyphosate
chemical_list: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D005998:Glycine; D006540:Herbicides; D010940:Plant Proteins; D000097797:Glyphosate
keywords: EPSPS; Echinochloa colona; glyphosate efficacy; glyphosate resistance; target-site mutation; temperature effect