ACCase mutations in Avena sterilis populations and their impact on plant fitness.
Avena sterilis (sterile oat) populations originating from wheat-growing regions of Greece, developed resistance to fenoxaprop, clodinafop and other herbicides. The partial ACCase gene sequence revealed six point mutations (Ile-1781-Leu, Trp-1999-Cys, Trp-2027-Cys, Ile-2041-Asn, Asp-2078-Gly, and Cys-2088-Arg) in 24 out of the 26 resistant (R) populations, confirming the molecular mechanism of resistance to ACCase-inhibiting herbicides. However, DNA sequence of two R populations did not reveal any known ACCase mutations, suggesting possible presence of unknown mutation or metabolism-based mechanism of resistance. The Cys-2088-Arg mutation is the first record for ACCase mutant conferring target-site resistance in A. sterilis worldwide. The evaluation of 12 R and 6 susceptible (S) populations under non-competitive field conditions did not indicate consistent mean growth rate differences, whereas the pot evaluation of the same (12 R and 6 S) populations grown in competition with wheat or in pure stands showed significant growth (fresh weight and panicle number) differences between six S populations and between six R populations containing the same ACCase mutation (Ile-2041-Asn). Finally, one S and five R (Trp-1999-Cys, Trp-2027-Cys, Ile-2041-Asn, Asp-2078-Gly, and Cys-2088-Arg) populations grown under field competitive conditions indicated fresh weight and panicle number differences in competition with other populations as compared with pure stands. These findings suggest clearly that the inconsistent fitness differences between R and S A. sterilis populations are not related with the ACCase resistance trait but they may result from other non-resistance fitness traits selected in their different geographical locations.
Department of Agricultural Technology, School of Agricultural Technology and Food and Nutrition Technology, Technological Educational Institute of Western Greece, 272 00 Amaliada, Greece.
Aristeidis P
AP
Papapanagiotou
Laboratory of Agronomy, School of Agriculture, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.
Maria I
MI
Paresidou
Syngenta Crop Protection UK Ltd., Jealott's Hill International Research Centre, Bracknell, Berks, UK.
Nikolaos S
NS
Kaloumenos
Laboratory of Agronomy, School of Agriculture, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece. Electronic address: eleftero@agro.auth.gr.
Ilias G
IG
Eleftherohorinos
D000103:Acetyl-CoA Carboxylase / Q000235:genetics*; D018554:Avena / Q000235:genetics* / Q000254:growth & development*; D056084:Genetic Fitness; D053209:Herbicide Resistance; D010940:Plant Proteins / Q000235:genetics*; D017354:Point Mutation
D010940:Plant Proteins; D000103:Acetyl-CoA Carboxylase
ACCase gene mutation; Avena sterilis; Fitness impact; Herbicide cross-resistance