Abstract
Rice (Oryza sativa L.) plants possess three homologous but distinct genes for cytosolic glutamine synthetase (GS1): these are OsGS1;1, OsGS1;2 and OsGS1;2. We characterized knockout mutants caused by insertion of endogenous retrotransposon Tos17 into OsGS1;1. This mutant contained undetectable amount of GS1 protein and its activity in the leaf blades.
Mutants showed severe retadation in growth rate under NH4+-containing hydroponic solution. Glutamine pool in the leaf blades of the mutants was approximately 60% lower than that of the wild-type. Microarray analysis successfully identified several genes, either up- or down-regulated, in the mutants.
The results indicate that GS1;1 is important for normal growth of rice and other two GS1 isoenzymes as well as GS2 were not able to compensate the function of GS1;1.
