Effects of nitrogen on the expression of ribulose-1,5- bisphosphate carboxylase/oxygenase small subunit multigene family members in Rice (Oryza sativa L.)

Five ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit genes identified in the rice (Oryza sativa) genome are designated as OsRBCS1, 2, 3, 4 and 5. OsRBCS1 transcripts were not detectable. The mRNA levels of OsRBCS2, OsRBCS3, OsRBCS4 and OsRBCS5 in leaf blades were increased by NH₄NO₃ supply to nitrogen-starved plants, but the extent of increment varied with the genes. The mRNA levels of OsRBCS2, OsRBCS3 and OsRBCS4 in leaf blades were increased by NH₄NO₃ or glutamine supply to detached shoots. On the other hand, NH₄NO₃ and glutamine had little effect on the expression of OsRBCS5 gene. The mRNA level of OsRBCS4 was increased only by cytokinin supply to the detached shoots. The expression of the promoters of OsRBCS2 and OsRBCS3 was enhanced by NH₄NO₃ supply.