In C3 crop species, such as soybeans or cowpeas, carbon dioxide from the air is combined in photosynthesis with a 5-carbon sugar, called ribulose biphosphate (RuBP), forming two 3-carbon molecules of phosphoglycerate (PGA). One-sixth of this carbon can be converted to sugars, and then into all the other compounds needed to maintain and grow the plant, but the other five-sixths of this carbon must be used to recycle RuBP—through 11 reactions—to allow carbon dioxide uptake to continue. These reactions that regenerate RubP limit photosynthesis with Rubisco, the enzyme that turns carbon dioxide into sugars. As global levels of carbon dioxide rise, the limitation imposed by this regeneration is becoming greater. By treating the regeneration of a system of reactions, our goal is to optimize resource distribution between these reactions to maximize the efficiency of RubP regeneration to deliver a sustainable increase in crop productivity.