PLANT PHYSIOLOGY , Vol 105, Issue 1 159-166, Copyright © 1994 by American Society of Plant Biologists
|
METABOLISM AND ENZYMOLOGY |
The Metabolites of the Herbicide L-Phosphinothricin (Glufosinate) (Identification, Stability, and Mobility in Transgenic, Herbicide-Resistant, and Untransformed Plants)
W. Droge-Laser, U. Siemeling, A. Puhler and I. Broer
Lehrstuhl fur Genetik, Fakultat fur Biologie (W.D.-L., A.P., I.B.), and Lehrstuhl fur Anorganische Chemie III (U.S.), Universitat Bielefeld, Universitatsstrasse, 33615 Bielefeld, Germany
The metabolism of the herbicide L-phosphinothricin (L-Pt) was analyzed in
tobacco (Nicotiana tabacum), alfalfa (Medicago sativa), and carrot (Daucus
carota). In transgenic, Pt-resistant plants expressing the
Pt-N-acetyltransferase gene (pat), L-Pt was acetylated, resulting in two
forms of N-acetyl-Pt (ac-Pt). In transgenic plants expressing only low
pat-encoded acetylating activity as well as in genetically unmodified
plants, three metabolic compounds 4-methylphosphinico-2-oxo-butanoic acid,
3-methylphosphinico-propanoic acid (MPP), and
4-methylphosphinico-2-hydroxy-butanoic acid (MHB) were identified. Hence,
the transgene-encoded acetylation of L-Pt competes with a plant-specific
degradation. The compounds MPP, MHB, and ac-Pt were found to be the final,
stable products of the plant's metabolic pathways. The mobility of these
stable compounds in the plant was investigated: L-Pt as well as the derived
metabolites were found to be preferentially transported to the upper
regions of the plant.
