title: An isoleucine residue within the carboxyl-transferase domain of multidomain acetyl-coenzyme A carboxylase is a major determinant of sensitivity to aryloxyphenoxypropionate but not to cyclohexanedione inhibitors.
abstract: A 3,300-bp DNA fragment encoding the carboxyl-transferase domain of the multidomain, chloroplastic acetyl-coenzyme A carboxylase (ACCase) was sequenced in aryloxyphenoxypropionate (APP)-resistant and -sensitive Alopecurus myosuroides (Huds.). No resistant plant contained an Ile-1,781-Leu substitution, previously shown to confer resistance to APPs and cyclohexanediones (CHDs). Instead, an Ile-2,041-Asn substitution was found in resistant plants. Phylogenetic analysis of the sequences revealed that Asn-2,041 ACCase alleles derived from several distinct origins. Allele-specific polymerase chain reaction associated the presence of Asn-2,041 with seedling resistance to APPs but not to CHDs. ACCase enzyme assays confirmed that Asn-2,041 ACCase activity was moderately resistant to CHDs but highly resistant to APPs. Thus, the Ile-2,041-Asn substitution, which is located outside a domain previously shown to control sensitivity to APPs and CHDs in wheat (Triticum aestivum), is a direct cause of resistance to APPs only. In known multidomain ACCases, the position corresponding to the Ile/Asn-2,041 residue in A. myosuroides is occupied by an Ile or a Val residue. In Lolium rigidum (Gaud.), we found Ile-Asn and Ile-Val substitutions. The Ile-Val change did not confer resistance to the APP clodinafop, whereas the Ile-Asn change did. The position and the particular substitution at this position are of importance for sensitivity to APPs.
authors.affiliation: Institut National de la Recherche Agronomique, Unité de Malherbologie et Agronomie, B.P. 86510, F-21065 Dijon cedex, France. delye@dijon.inra.fr
authors.forename: Christophe
authors.initials: C
authors.lastname: Délye
authors.forename: Xiao-Qi
authors.initials: XQ
authors.lastname: Zhang
authors.forename: Claire
authors.initials: C
authors.lastname: Chalopin
authors.forename: Séverine
authors.initials: S
authors.lastname: Michel
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Powles
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D003512:Cyclohexanones / Q000494:pharmacology*; D006540:Herbicides / Q000494:pharmacology*; D007532:Isoleucine / Q000235:genetics / Q000378:metabolism*; D019684:Magnoliopsida / Q000187:drug effects* / Q000201:enzymology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D011110:Polymorphism, Genetic / Q000235:genetics; D011422:Propionates / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D003512:Cyclohexanones; D006540:Herbicides; D011422:Propionates; D007532:Isoleucine; D000103:Acetyl-CoA Carboxylase