Douglas Orr, André Alcântara, Maxim Kapralov, John Andralojc, Elizabete Carmo-Silva, and Martin A. J. Parry

The threat to global food security of stagnating yields and population growth makes increasing crop 34 productivity a critical goal over the coming decades. One key target for improving crop productivity and 35 yields is increasing the efficiency of photosynthesis. Central to photosynthesis is ribulose-1,5- 36 bisphosphate carboxylase/oxygenase, Rubisco, which is a critical but often rate-limiting component. Here 37 we present full Rubisco catalytic properties measured at three temperatures for 75 plants species 38 representing both crops and undomesticated plants from diverse climates. Some newly characterised 39 Rubiscos were naturally 'better' compared to crop enzymes and have the potential to improve crop 40 photosynthetic efficiency. The temperature response of the various catalytic parameters was largely 41 consistent across the diverse range of species, though absolute values showed significant variation in 42 Rubisco catalysis, even between closely related species. An analysis of residue differences amongst the 43 species characterised identified a number of candidate amino acid substitutions that will aid in advancing 44 engineering of improved Rubisco in crop systems. This study provides new insights on the range of 45 Rubisco catalysis and temperature response present in nature, and provides new information to include in 46 models from leaf to canopy and ecosystem scale.