Metabolism of the herbicide glufosinate‐ammonium in plant cell cultures of transgenic (rhizomania‐resistant) and non‐transgenic sugarbeet (Beta vulgaris), carrot (Daucus carota), purple foxglove (Digitalis purpurea) and thorn apple (Datura stramonium)

The metabolism of the herbicide glufosinate‐ammonium was investigated in heterotrophic cell suspension and callus cultures of transgenic (bar‐gene) and non‐transgenic sugarbeet (Beta vulgaris). Similar studies were performed with suspensions of carrot (Daucus carota), purple foxglove (Digitalis purpurea) and thorn apple (Datura stramonium). ¹⁴C‐labelled chemicals were the (racemic) glufosinate, L ‐glufosinate, and D ‐glufosinate, as well as the metabolites N‐acetyl L ‐glufosinate and 3‐(hydroxymethylphosphinyl)propionic acid (MPP). Cellular absorption was generally low, but depended noticeably on plant species, substance and enantiomer. Portions of non‐extractable residues ranged from 0.1% to 1.2% of applied ¹⁴C. Amounts of soluble metabolites resulting from glufosinate or L ‐glufosinate were between 0.0% and 26.7% of absorbed ¹⁴C in non‐transgenic cultures and 28.2% and 59.9% in transgenic sugarbeet. D ‐Glufosinate, MPP and N‐acetyl L ‐glufosinate proved to be stable. The main metabolite in transgenic sugarbeet was N‐acetyl L ‐glufosinate, besides traces of MPP and 4‐(hydroxymethylphosphinyl)butanoic acid (MPB). In non‐transgenic sugarbeet, glufosinate was transformed to a limited extent to MPP and trace amounts of MPB. In carrot, D stramonium and D purpurea, MPP was also the main product; MPB was identified as a further trace metabolite in D stramonium and D purpurea. © 2001 Society of Chemical Industry