Effects of Glutamine Synthetase Inhibitors on Rice Sterility

Abstract

Bialaphos, a glutamine synthetase (GS) inhibitor, is an effective inducer of rice sterility. L-Phosphinothricin (L-PTC), a metabolite of bialaphos, is the real inhibitor of GS from the results of an enzyme assay of GS from rice plants. Bialaphos and L-PTC induced a high level of sterility in rice at a concentration of 0.1 mM at the meiosis stage. The complete inhibition of GS activity was induced by 24-h treatments with 0.1 mM of bialaphos and L-PTC, respectively. These inhibitions continued until anthesis. In proportion to the inhibition of GS activity, the free ammonia content was increased in the panicles after treating with 0.1 mM of bialaphos and L-PTC. This accumulation of ammonia continued until anthesis. These results suggest that ammonia accumulating in the panicles as a result of GS inhibition directly caused sterility in rice.