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1988 (1)
1Author    Klaus Kobek, Manfred Focke, HartmutK. LichtenthalerRequires cookie*
 Title    Fatty-Acid Biosynthesis and Acetyl-CoA Carboxylase as a Target of Diclofop, Fenoxaprop and other Aryloxy-phenoxy-propionic Acid Herbicides  
 Abstract    The effect of the herbicides and aryloxy-phenoxy-propionic acid derivatives diclofop, fenoxa-prop, fluazifop and haloxyfop and their ethyl, methyl or butyl esters on the de novo fatty-acid biosynthesis of isolated chloroplasts was investigated with intact chloroplasts isolated from sensi-tive grasses (Poaceae) and tolerant dicotyledonous plants (Pisum, Spinacia). The 4 herbicides (free-acid form) block the de novo fatty-acid biosynthesis ([2-l4 C]acetate incorporation into the total fatty-acid fraction) of the sensitive Avena chloroplasts in a dose-dependent manner. The / 50 -values (a 50% inhibition of the [ 14 C]acetate incorporation) lie in the range of 10~ 7 to 2 x 10~ 6 M. The ethyl or methyl esters (diclofop, fenoxaprop, haloxyfop) and butyl ester (fluazifop) do not affect the de novo fatty-acid biosynthesis of isolated chloroplasts or only at a very high concentra-tion of ca. 10" 4 M. In contrast, the de novo fatty-acid biosynthesis of the tolerant dicotyledonous species (pea, spinach) is not affected by the 4 aryloxy-phenoxy-propionic acid herbicides. In an enzyme preparation isolated from chloroplasts of the herbicide-sensitive barley plants the de novo fatty-acid biosynthesis from [ 14 C]acetate and [ 14 C]acetyl-CoA is blocked by all 4 herbi-cides (free acids), whereas that of [ l4 C]malonate and [ I4 C]malonyl-CoA is not affected. This strongly suggests that the target of all 4 herbicides (free-acid form) is the acetyl-CoA carboxylase within the chloroplasts. The applied ester derivatives, in turn, which are ineffective in the isolated chloroplast test system, have equally little or no effect on the activity of the acetyl-CoA carboxyl-ase. It is assumed that the acetyl-CoA carboxylase of the tolerant dicot plants investigated is modified in such a way that the 4 herbicides cannot bind to and affect the target. 
  Reference    Z. Naturforsch. 43c, 47—54 (1988); received November 2 1987 
  Published    1988 
  Keywords    Acetyl-CoA Carboxylase, Chloroplast Metabolism, de novo Fatty-Acid Biosynthesis, Fluazifop, Haloxyfop, Herbicide Sensitivity 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0047.pdf 
 Identifier    ZNC-1988-43c-0047 
 Volume    43