Correlating Rubisco catalytic and sequence diversity within C-3 plants with changes in atmospheric CO2 concentrations

摘要

CO2 fixation in higher plants is catalysed by Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase; EC 4.1.1.39) whose catalysis has a pervasive influence on the efficiency of photosynthesis and growth. Surprisingly, Rubisco is endowed with catalytic imperfections, which include confusion of substrate CO2 with O2 and a slow turnover rate. The confusion between CO2 and O2 has become exacerbated through the onset of oxygenic photosynthesis that has significantly reduced the earth's atmospheric CO2/O2 ratio. To compensate for these imperfections in catalysis, the simpler evolutionary route for C3 plants is to make more Rubisco to maintain viable CO2 assimilation rates – despite the significant nitrogen and energy cost to the plant. In this issue of Plant, Cell & Environment, Galmes et?al. (2014) presented Rubisco catalytic data from diverse C3 terrestrial plants from different phylogenetic lineages that have adapted to varying environmental conditions. Their findings help better understand how Rubisco function in C3 plants has adapted to atmospheric CO2 and O2 changes. Understanding such puzzles is a key to identifying solutions for improving Rubisco catalysis that, in coordination with other photosynthesis-enhancing approaches, are aimed at delivering a second ‘green revolution’ to increase productivity in globally important C3 grain crops such as wheat and rice (Evans & von Caemmerer 2011).