Glufosinate metabolism in excised shoots and leaves of twenty plant species

Abstract

The metabolism of the herbicide 14C-glufosinate (GA) was studied in excised shoots and leaves of 20 weed and nonweed species; GA was fed through the xylem. After 24 or 48 h of incubation, the plant material was examined for phytotoxic symptoms, analyzed by autoradiography, and extracted. The extract was cleaned up and analyzed by high-performance liquid chromatography. GA and its metabolites were identified by cochromatography with authentic 14C-labelled reference compounds. 14C-GA was rapidly absorbed by the excised plant parts. Most of the radioactivity (91.3 to 99.7%) in the shoots and leaves was extractable. The main metabolite observed with all species was 3-(hydroxymethylphosphinyl)propionic acid (MPP); lower amounts of 2-hydroxy-4-(hydroxymethylphosphinyl)butanoic acid (MHB) were also found in 14 species. Metabolic rates of GA varied considerably ranging between 13.1 and 2,836.5 ng GA h−1 mg−1 protein. The species with the highest rates of metabolism of GA were Galium verum (2,836.5 ng GA h−1 mg−1 protein), Lythrum hyssopifolia (846.0 ng GA h−1 mg−1 protein), and Digitalis purpurea (494.8 ng GA h−1 mg−1 protein). The mean value across all species was 275.9 ng GA h−1 mg−1 protein.

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)

“…Except for MPA, these metabolites have already been described in the literature (Dröge et al, 1992;Dröge-Laser et al, 1994;Jansen et al, 2000;Komoßa and Sandermann, 1992;Müller et al, 1999;Müller et al, 2001). As shown by these studies, the first step in the metabolic pathway of LGA in sensitive plants is degradation of the amino group by deamination to the corresponding alpha-oxo-carboxylic acid (PPO).…”

“…The D-enantiomer was found to be stable in these sterile plants. Recent studies of Jansen et al (2000) on glufosinate metabolism in excised shoots and leaves of twenty plant species showed MPP to be the main metabolite in all species tested, together with low amounts of MHB in 14 species.…”

The biology of Canadian weeds. 142. Camelina alyssum (Mill.) Thell.; C. microcarpa Andrz. ex DC.; C. sativa (L.) Crantz.

“…In a German study of the metabolism of 14 Cglufosinate (GA) (Jansen et al 2000), excised shoots and leaves of C. alyssum absorbed a high percentage (87%) of the radioactivity applied, had one of the lowest portions of non-extractable residues (0.3%) and a high rate of recovered radioactivity (ca. 88%).…”

Absorption and Penetration of Herbicides Viewed in Metabolism Studies: Case of Glufosinate and Imazamox in Wheat

“…In metabolism studies, the preferred methods for analysis of glufosinate and metabolites in plants are based on LC separation and radioactivity detection (31,32), which require simple sample preparation protocols (usually precipitation of polysaccharides, protein and peptides and subsequent filtration or centrifugation), thus preventing or minimizing potential losses of the target analytes (particularly low concentrated metabolites) (32). Nevertheless, radioactivity-based methods have as major limitations the high cost of reagents, loss of radioactivity by quenching, difficulties in waste management and their inability to identify chemical structures of the metabolites.…”