Single-site mutations in the carboxyltransferase domain of plastid acetyl-CoA carboxylase confer resistance to grass-specific herbicides

Abstract

Grass weed populations resistant to aryloxyphenoxypropionate (APP) and cyclohexanedione herbicides that inhibit acetyl-CoA carboxylase (ACCase; EC 6.4.1.2) represent a major problem for sustainable agriculture. We investigated the molecular basis of resistance to ACCase-inhibiting herbicides for nine wild oat (Avena sterilis ssp. ludoviciana Durieu) populations from the northern grain-growing region of Australia. Five amino acid substitutions in plastid ACCase were correlated with herbicide resistance: Ile-1,781-Leu, Trp-1,999-Cys, Trp-2,027-Cys, Ile-2,041-Asn, and Asp-2,078-Gly (numbered according to the Alopecurus myosuroides plastid ACCase). An allele-specific PCR test was designed to determine the prevalence of these five mutations in wild oat populations suspected of harboring ACCase-related resistance with the result that, in most but not all cases, plant resistance was correlated with one (and only one) of the five mutations. We then showed, using a yeast gene-replacement system, that these single-site mutations also confer herbicide resistance to wheat plastid ACCase: Ile-1,781-Leu and Asp-2,078-Gly confer resistance to APPs and cyclohexanediones, Trp-2,027-Cys and Ile-2,041-Asn confer resistance to APPs, and Trp-1,999-Cys confers resistance only to fenoxaprop. These mutations are very likely to confer resistance to any grass weed species under selection imposed by the extensive agricultural use of the herbicides.aryloxyphenoxypropionate ͉ Avena ͉ cyclohexanedione

Resistance to ACCase inhibitors in Eleusine indica from Brazil involves a target site mutation

“…These high values for the RF factors are strong evidence of a target site mechanism of resistance in the E. indica biotype from Mato Grosso, Brazil. Further molecular studies have indicated an Asp-2078-Gly substitution in the R population endowed resistance to both APP and CHD herbicides (Figure 1). The same mutation has been reported in other grass weeds (Délye et al, 2005;Liu et al, 2007;Yu et al, 2007;Hochberg et al, 2009) and endows resistance of these to ACCase-inhibitors.…”

“…Cross-resistance is referred as resistance to several herbicides that affect one target enzyme, and usually is endowed by a single gene (Délye, 2005). Herbicide crossresistance on many plant species have been documented due to ACCase enzymes with amino acid substitutions at the positions: 1781 (White et al., 2005), 1999 (Liu et al, 2007); 2027 (Délye et al, 2003;Liu et al, 2007;Gherekhloo et al, 2012); 2041 (Délye et al, 2003;Zhang & Powles, 2006;Liu et al, 2007); 2078 (Délye et al, 2005;Kaundun, 2010;Hochberg et al, 2009); at 2088 (Yu et al, 2007), and 2096 (Délye et al, 2005). The choice of herbicide to control a resistant population is complicated by the fact that the specific amino acid substitutions in one enzyme may give different patterns of cross resistance to the different herbicides that affect it (Powles &Yu, 2010).…”

Recombinant yeast screen for new inhibitors of human acetyl-CoA carboxylase 2 identifies potential drugs to treat obesity

“…The cytosolic enzyme (ACC2) makes malonyl-CoA for very long-chain fatty acids, flavonoids, and signaling compounds. The plastid form of the enzyme in wheat and other grasses is sensitive to three classes of highly effective herbicides: aryloxyphenoxypropionates, cyclohexanediones, and pinoxaden (2)(3)(4)(5). We have shown that the parasite Toxoplasma gondii has two ACCs as well, one located in the apicoplast, where it is involved in de novo fatty acid synthesis for lipids and the lipoic acid cofactor of pyruvate dehydrogenase.…”

Diversity of Acetyl-Coenzyme A Carboxylase Mutations in Resistant Lolium Populations: Evaluation Using Clethodim

“…1 In studies with resistant A. myosuroides and L. rigidum populations from France, neither heterozygous nor homozygous mutants of 1781-Leu were found to be resistant to clethodim, haloxyfop, or clodinafop, and the genotype 1781-Leu/2041-Asn was not found to be resistant to clethodim in a seed germination assay (Délye et al, 2002b(Délye et al, , 2005. Conversely, in a recent study in Avena sterilis, 2027-Cys and 2041-Asn mutations were found to be associated with resistance to the CHD herbicides tralkoxydim and sethoxydim, respectively (Liu et al, 2007). Similarly, the 2041-Asn mutation in Phalaris paradoxa was found to confer resistance to most CHD herbicides with a lower level resistance to clethodim (Hochberg et al, 2007).…”

“…The Asp-2078-Gly mutation confers resistance to many APP and CHD herbicides including clethodim. The Trp-1999-Cys mutation confers resistance only to the APP herbicide fenoxaprop (Liu et al, 2007).…”