Expert View: The nitrogen cost of photosynthesis (J Exp Bot)

Modern crop production is intimately linked to the availability of nitrogen.  Photosynthetic proteins (including rubisco) account for most of the nitrogen in leaves, a significant amount of which is removed during harvesting and must be replenished primarily through the application of synthetic nitrogen fertilisers. In this Expert View, Evans & Clarke revisit the nitrogen budget of a C₃ leaf based on modern x-ray crystallography and mass spectrometry data.  The authors discuss the difficulties of applying generalised relationships between photosynthesis and leaf nitrogen contents to the ecosystem scale, and consider recent advances in remote sensing to measure some of the required parameters. They then discuss the relationship between carbon assimilation and the synthesis of nitrogenous compounds, and how increasing atmospheric CO₂ concentrations will change the nitrogen content of our crops in the future.  The manuscript finishes by assessing the nitrogen cost of some of the current strategies for improving photosynthesis, with an emphasis on maintaining current levels of grain protein levels.  (Summary by Mike Page) J Exp Bot 10.1093/jxb/ery366