The action of 2-amino-4-(methylphosphinyl)-butanoic acid (phosphinothricin) and its 2-oxo-derivative on the metabolism of cyanobacteria and higher plants

When adequate concentrations of phosphinothricin (a potent inhibitor of glutamine synthetase) are added to Anacystis nidulans cells suspended in nitrate medium, ammonia excretion into the medium takes place. Similarly, when phosphinothricin is added to nitrogen fixing cultures of Anabaena ATCC 33047, ammonia is also released at high rates. Methionine sulphoximine, phosphinothricin and its 2-oxo-derivative (1 mM) stimulate ammonia production and cause a sharp drop in glutamine and asparagine concentrations, when fed to leaves of Triticum, Pisum and Helianthus. Less pronounced effects were detected with the leaves of a C₄ plant Zea.