Effect of Sucrose on Glutamine Synthetase and Ribulose-1,5-bisphos-phate Carboxylase/Oxygenase in Leaves of Rice Seedlings

In the current report, we have investigated that the effect of sucrose on GSand its isozymes as well as ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco) of the leaves of rice seedlings. GSactivity was decreased with the increase of sucrose concentrations whether the illumination of light or the dark. The levels of the soluble proteins and Rubisco were not obviously influenced by sucrose at the illumination of light or the dark although their changes were diffe rent. Native-PAGE and activity staining showed that the inhibition of sucrose to GS2 expression was strengthened with sucrose concentrations but GS1 was not clearly affected in the illumination of ligh or the dark. These results suggested that sucrose can not induce the expression of GSin leaves of rice seedlings as light.