Plant ribulose-1, 5-bisphosphate carboxylase/oxidase (Rubisco) has two activities, and the one is carboxylation to assimilate CO2 to produce food for the biosphere, and the other one is oxidation to generate toxic 2-phosphoglycolate to commit the photorespiration pathway. For C3 plants, about 1/3 assimilation products of photosynthesis are used for photorespiration. However, knocking out photorespiration genes directly is unable to improve plant biomass, but also induces lethal phenotypes in most cases. Reasonable optimization of the photorespiration pathway has the potential of large improvements in plant biomass and crop productivity. Here, we review the function and gene loop of the photorespiration pathway, and discuss the approaches to engineer and optimize this pathway to increase crop yields.
