phosphinothricin

Phosphinothricin is a natural phosphinic acid amino acid that inhibits glutamine synthetase. It is the active component of the non-selective herbicide glufosinate, typically used as the ammonium salt glufosinate ammonium. In nature, phosphinothricin occurs in the phosphinothricin tripeptide (PTT) antibiotic produced by Streptomyces hygroscopicus and related species; in commercial products it is supplied as a salt form optimized for uptake and stability.

Mechanism of action: Phosphinothricin inhibits glutamine synthetase, the enzyme that converts ammonium into glutamine. Inhibition causes ammonium accumulation and disruption of nitrogen metabolism, leading to rapid chlorosis, necrosis, and plant death. The compound is non-selective and acts on a wide range of plant tissues; it can be absorbed through leaves and roots and is distributed systemically within the plant.

Uses and genetic engineering: Glufosinate is used as a broad-spectrum herbicide in conventional agriculture and in specialty applications. In plant biotechnology, resistance to phosphinothricin is conferred by the bar gene, encoding phosphinothricin acetyltransferase (PAT), which detoxifies the compound by acetylation and serves as a selectable marker during plant transformation.

Form and regulation: Phosphinothricin exists as the free acid in research contexts and as the glufosinate ammonium salt in commercial products. It is subject to regulatory controls in many jurisdictions because of concerns about non-target toxicity and environmental impact. In soils, degradation is relatively rapid through microbial activity, reducing persistence.