title: Effect of herbicide resistance endowing Ile-1781-Leu and Asp-2078-Gly ACCase gene mutations on ACCase kinetics and growth traits in Lolium rigidum.
abstract: The rate of herbicide resistance evolution in plants depends on fitness traits endowed by alleles in both the presence and absence (resistance cost) of herbicide selection. The effect of two Lolium rigidum spontaneous homozygous target-site resistance-endowing mutations (Ile-1781-Leu, Asp-2078-Gly) on both ACCase activity and various plant growth traits have been investigated here. Relative growth rate (RGR) and components (net assimilation rate, leaf area ratio), resource allocation to different organs, and growth responses in competition with a wheat crop were assessed. Unlike plants carrying the Ile-1781-Leu resistance mutation, plants homozygous for the Asp-2078-Gly mutation exhibited a significantly lower RGR (30%), which translated into lower allocation of biomass to roots, shoots, and leaves, and poor responses to plant competition. Both the negligible and significant growth reductions associated, respectively, with the Ile-1781-Leu and Asp-2078-Gly resistance mutations correlated with their impact on ACCase activity. Whereas the Ile-1781-Leu mutation showed no pleiotropic effects on ACCase kinetics, the Asp-2078-Gly mutation led to a significant reduction in ACCase activity. The impaired growth traits are discussed in the context of resistance costs and the effects of each resistance allele on ACCase activity. Similar effects of these two particular ACCase mutations on the ACCase activity of Alopecurus myosuroides were also confirmed.
authors.affiliation: Australian Herbicide Resistance Initiative (AHRI) - School of Plant Biology, University of Western Australia, WA, 6009, Australia IFEVA - CONICET - Facultad de Agronomía, Universidad de Buenos Aires (UBA), Buenos Aires, 1417, Argentina vila@ifeva.edu.ar.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Vila-Aiub
authors.affiliation: Australian Herbicide Resistance Initiative (AHRI) - School of Plant Biology, University of Western Australia, WA, 6009, Australia.
authors.forename: Qin
authors.initials: Q
authors.lastname: Yu
authors.affiliation: Australian Herbicide Resistance Initiative (AHRI) - School of Plant Biology, University of Western Australia, WA, 6009, Australia.
authors.forename: Heping
authors.initials: H
authors.lastname: Han
authors.affiliation: Australian Herbicide Resistance Initiative (AHRI) - School of Plant Biology, University of Western Australia, WA, 6009, Australia.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Powles
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000235:genetics* / Q000378:metabolism; D056084:Genetic Fitness; D053209:Herbicide Resistance; D006540:Herbicides / Q000494:pharmacology*; D007700:Kinetics; D008129:Lolium / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D006540:Herbicides; D010940:Plant Proteins; D000103:Acetyl-CoA Carboxylase
keywords: ACCase activity; Alopecurus myosuroides; RGR.; competition; resistance cost; resistance mutation