Photorespiratory ammonia assimilation in the leaves of barley, sorghum and Moricandia arvensis.

Effects of methionine sulphoximine (MSX) on glutamine synthetase activity and ammonia accumulation in the leaves of barley, sorghum and Moricandia arvensis were studied. Glutamine synthetase activity of sorghum leaves was relatively resistant to MSX treatment during initial stages. All the three plant species exhibited considerable accumulation of ammonia arising from non-photorespiratory sources, in response to MSX treatment. Minimal estimates of the rate of glycine decarboxylation were made employing MSX and isonicotinyl hydrazide together in the treatment solution. Changes in the pool sizes of amino acids involved in photorespiratory nitrogen metabolism as affected by MSX have also been investigated.