Inhibition of ACCase220 and ACCase240 isozymes from sethoxydim-resistant and -susceptible maize hybrids.
Acetyl-coenzyme A carboxylase (ACCase) isozymes were separated from cyclohexanedione-resistant and -susceptible maize. ACCase240 from resistant maize was 3.7-, >77-, and 12.8-fold more resistant to inhibition by clethodim, sethoxydim, and tralkoxydim, respectively, than ACCase240 from susceptible maize. The resistant ACCase240 preparation had 3.0-fold more protein and 14.5-fold lower specific activity than susceptible ACCase240. Resistant ACCase240 has a V(max) 5.5-fold lower than that of susceptible ACCase240, whereas apparent K(m) values were similar. ACCase220 from resistant maize was >25- and 7.2-fold more resistant to inhibition by sethoxydim and tralkoxydim, respectively, than susceptible ACCase220 but was inhibited to the same extent by clethodim. In summary, sethoxydim-resistant corn has an altered herbicide-resistant ACCase220 isozyme and increased expression of a less efficient, herbicide-resistant ACCase240 isozyme. However, to what extent alteration of both isozymes contributes to sethoxydim resistance is not clear.
Incledon
B J
BJ
Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Hall
J C
JC
D000103:Acetyl-CoA Carboxylase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D003512:Cyclohexanones; D006540:Herbicides; D006824:Hybridization, Genetic; D007527:Isoenzymes / Q000032:analysis*; D007700:Kinetics; D003313:Zea mays / Q000187:drug effects / Q000201:enzymology*
D003512:Cyclohexanones; D006540:Herbicides; D007527:Isoenzymes; C049437:sethoxydim; D000103:Acetyl-CoA Carboxylase