Document Detail

Basis of selectivity of cyhalofop-butyl in Oryza sativa L.
MedLine Citation:
PMID:  16160841     Owner:  NLM     Status:  MEDLINE    
Cyhalofop-butyl (CB), 2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid, butyl ester (R), is an aryloxyphenoxypropionate (AOPP) herbicide for postemergence use in rice to control grasses, mainly Echinochloa spp. Similar to other AOPP and cyclohexanedione herbicides, the site of action of CB is acetyl-coenzyme A carboxylase (ACCase), an enzyme in fatty acid biosynthesis. The mechanisms involved in the selectivity of CB in rice (Oryza sativa L.)-absorption, translocation, metabolism, and ACCase susceptibility-were studied. Studies of in vitro inhibition of ACCase in E. oryzoides and O. sativa L. species discounted any differential active site sensitivity as the basis of tolerance to CB. The O. sativa L. cuticle was uniformly covered by waxes, with predominantly unshaped large waxes randomly distributed, obtaining absorption values of under 30%, 24 h after application (HAA). The E. oryzoides cuticle formed a non-uniform covered reticule, with less wax density and areas lacking in waxes reaching maximum values of absorption rising to 73%, 24 HAA. Translocation studies revealed no significant differences, either between species, or between times, remaining in the treated leaf. There was a good correlation between the rate of metabolism and plant tolerance. Plant metabolism studies demonstrated that tolerant rice inactivated the esterases producing a lack of functionality thus reducing the conversion of CB to cyhalofop acid, which is the active form of the herbicide. Moreover, it increased the metabolism of the herbicide forming non toxic metabolites much faster than E. oryzoides. It was concluded that the basis of rice tolerance to CB was a lack of esterase functionality, a reduced absorption through the cuticle and an increase in cyhalofop acid metabolism.
J P Ruiz-Santaella; A Heredia; R De Prado
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-09-14
Journal Detail:
Title:  Planta     Volume:  223     ISSN:  0032-0935     ISO Abbreviation:  Planta     Publication Date:  2006 Jan 
Date Detail:
Created Date:  2005-12-28     Completed Date:  2006-04-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1250576     Medline TA:  Planta     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  191-9     Citation Subset:  IM    
Department of Agricultural Chemistry and Edaphology, University of Córdoba, Córdoba, Spain.
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MeSH Terms
Acetyl-CoA Carboxylase / metabolism
Butanes / metabolism*,  pharmacology*
Dose-Response Relationship, Drug
Echinochloa / anatomy & histology,  drug effects*,  metabolism
Herbicides / metabolism*,  pharmacology*
Microscopy, Electron, Scanning
Models, Biological
Nitriles / metabolism*,  pharmacology*
Oryza sativa / anatomy & histology,  drug effects*,  metabolism
Plant Proteins / metabolism
Time Factors
Reg. No./Substance:
0/Butanes; 0/Herbicides; 0/Nitriles; 0/Plant Proteins; 0/cyhalofop-butyl; EC Carboxylase

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