Reduced nitrogen allocation to expanding leaf blades suppresses ribulose-1,5-bisphosphate carboxylase/oxygenase synthesis and leads to photosynthetic acclimation to elevated CO2 in rice

Abstract

Net photosynthetic rate (PN) measured at elevated CO2 concentration (Ce), ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), and nitrogen (N) content in rice leaves decreased significantly after exposure to long term Ce. The reduction in PN, Rubisco, and leaf N at Ce was similar for the last fully expanded leaf blade (LFELB) and expanding leaf blade (ELB). Spatial leaf N content in the ELB was highest in the zone of cell division, sharply declined as cell expansion progressed and gradually increased with cell maturation. Maximum reduction in spatial leaf N and Rubisco content was found at Ce only within cell expansion and maturation zones. The spatial leaf N content correlated well with the amount of Rubisco synthesized during leaf expansion, suggesting that N deposition into the expanding leaf blade may be the key for Rubisco synthesis and possibly photosynthetic acclimation to Ce. © 2011 Springer Science+Business Media B.V.