The first enzyme involved in carbon fixation is Rubisco. This enzyme is important, but also inefficient because it can bind with oxygen instead of carbon dioxide, resulting in wasted carbon and energy in photorespiration.
A way to overcome the limitation of Rubisco in modern crops is to search for a Rubisco among wild plants that has a higher specificity for CO2, meaning that that it is less likely to bind to oxygen. RIPE is searching a range of algae and wild plants for a better Rubisco with higher specificity and faster binding rates. These will then be engineered into crops to replace the current, less efficient enzyme.
Obstacles to implementation: We have already seen some success; at least one algal Rubisco has been engineered into tobacco. Yet because Rubisco is composed of two subunits, one coded for by DNA in the nucleus and one by DNA in the chloroplast, which must then assemble into a functional complex, this is a high risk approach.