A comparative investigation of the metabolism of the herbicide glufosinate in cell cultures of transgenic glufosinate-resistant and non-transgenic oilseed rape (Brassica napus) and corn (Zea mays).
To obtain information on differences between the metabolic pathways of the herbicide glufosinate (trade names: BASTA, LIBERTY) in non-transgenic, glufosinate-sensitive plants and in transgenic, glufosinate-resistant plants, the metabolism of 14C-labeled glufosinate and its enantiomers L- and D-glufosinate was studied using cell cultures of oilseed rape and corn. Transformation of glufosinate in both sensitive and transgenic rape cells remained at a low rate of about 3-10% in contrast to corn cells, where 20% was transformed in sensitive and 43% in transgenic cells after 14 days of incubation, the rest remaining as unchanged glufosinate. In sensitive rape and corn cells the main metabolite was 4-methylphosphinico-2-oxo-butanoic acid (PPO) with 7.3 and 16.4%, respectively, together with low amounts of 3-methylphosphinicopropionic acid (MPP), 4-methylphosphinico-2-hydroxybutanoic acid (MHB), 4-methylphosphinicobutanoic acid (MPB) and 2-methylphosphinicoacetic acid (MPA). An additional metabolite formed in transgenic cell cultures was 2-acetamido-4-methylbutanoic acid (N-acetyl-L-glufosinate, NGA), which was formed at rates of 3.2% in rape and 16.1% in corn. A further minor metabolite, not yet identified, was detected in both cell types. The liberation of 0.2% 14CO2 indicates further metabolic steps prior to a limited mineralization in plant cell cultures. L-glufosinate was transformed into the same metabolites as the glufosinate racemate. D-glufosinate was not metabolized.
Ruhland
Monika
M
Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, Aussenstelle München, Menzinger Strasse 54, 80638 München, Germany.
Engelhardt
Gabriele
G
Pawlizki
Karlheinz
K
D000613:Aminobutyrates / Q000378:metabolism*; D029688:Brassica napus / Q000235:genetics*; D002245:Carbon Dioxide / Q000032:analysis; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D018929:Cell Culture Techniques; D006540:Herbicides / Q000378:metabolism*; D007305:Insecticide Resistance / Q000235:genetics; D030821:Plants, Genetically Modified; D003313:Zea mays / Q000235:genetics*
D000613:Aminobutyrates; D002250:Carbon Radioisotopes; D006540:Herbicides; D002245:Carbon Dioxide; C003121:phosphinothricin