Differences between Maize and Rice in N-use Efficiency for Photosynthesis and Protein Allocation

Abstract

The N-use efficiency for photosynthesis was higher in a C4 plant, maize, than in a C3 plant, rice, including rbcS antisense rice with optimal ribulose-1,5-bisphosphate carboxylase (Rubisco) content for CO2-saturated photosynthesis, even when photosynthesis was measured under saturating CO2 conditions. The N cost for the C4 cycle enzymes in maize was not large, and the lower amount of Rubisco allowed a greater N investment in the thylakoid components. This greater content of the thylakoid components as well as the CO2 concentrating mechanism may support higher N-use efficiency for photosynthesis in maize.