Assessment of acetolactate synthase (ALS) tolerance to imazethapyr in red rice ecotypes (Oryza spp) and imidazolinone tolerant/ resistant rice (Oryza sativa) varieties.
Three red rice ecotypes (Oryza spp), including LA 5, MS 5 and TX 4, were evaluated for acetolactate synthase resistance/tolerance to imazethapyr. The red rice ecotypes were compared with a tolerant line (CL-121), a resistant line (CL-161) and a conventional rice variety (Cypress). Based on enzymatic activity, the mean I(50) values were 1.5, 1.1, 1.5, 1.6, 20.8 and 590.6 microM imazethapyr, respectively, for LA 5, MS 5, TX 4, Cypress, CL-121 and CL-161. CL-161 was 32 times more resistant than CL-121 and at least 420 times more resistant than the average of the red rice ecotypes and Cypress. Results from the acetolactate synthase (ALS) assay showed that red rice ecotypes and Cypress had high susceptibility to imazethapyr when compared with the tolerant CL-121 and the resistant CL-161. Measurable enzymatic tolerance to ALS-inhibiting herbicides has not yet developed in these red rice ecotypes.
Avila
Luis A
LA
Texas A&M University, Research Fellow CAPES/Brazil and Universidade Federal de Santa Maria, Departamento de Fitotecnia, 97105-900 Santa Maria, RS, Brazil.
Lee
Do-Jin
DJ
Senseman
Scott A
SA
McCauley
Garry N
GN
Chandler
James M
JM
Cothren
J Tom
JT
D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D006540:Herbicides / Q000494:pharmacology*; D009539:Nicotinic Acids / Q000494:pharmacology*; D012275:Oryza / Q000145:classification / Q000187:drug effects* / Q000201:enzymology; D013045:Species Specificity
D006540:Herbicides; D009539:Nicotinic Acids; C093630:imazethapyr; D000095:Acetolactate Synthase