A new study from scientists based in the Australian National University and in the University of Wollongong, also in Australia, may have come up with the solution. The research team used genetic engineering to introduce a modified version of one of Rubisco's partner chaperone proteins, RAF1. Phylogenetic analysis revealed that Rubisco and RAF-1 had evolved together and when modified Rubisco is introduced into plants, it requires a complementary modified RAF-1. When both modified tobacco Rubisco and RAF-1 were introduced into the model Arabidopsis plant, plants were produced that had increased Rubisco biogenesis and improved leaf phosynthesis and growth. The study is published in the journal Proceedings of the National Academy of Sciences.
The current study results suggest that the issues encountered in improving Rubisco performance in other studies may have arisen from misunderstanding of how highly complex the structure of Rubisco is. The enzyme has 16 pieces that requires the assistance of more than 12 other proteins, including the RAF-1 chaperone, for correct assembly. Research team leader Dr Spencer Whitney of the Australian National University explained the significance of the study in terms of food-security: "Understanding the partnership with RAF1 has important implications with regard to ongoing efforts to accelerate the sluggish activity of Rubisco - a key goal for improving crop productivity. In a world with increasing demands for food, this is a milestone towards increasing the photosynthetic rate in crop plants that rely heavily on Rubisco." These would include staple food crops such as wheat and rice, as well as other important commercial crops such as cotton. Dr Whitney added: "The finding also explains why our prior attempts to insert more efficient versions of Rubisco from some algae into plant leaves have failed - they require different chaperones to those available in leaf cells."
The authors concluded that the outcomes of their study: “have application to the growing interest into identifying and implementing strategies to supercharge photosynthesis to improve crop productivity and stem global food-security concerns.”
Reference: Whitney SM, Birch R, Kelso C, Beck JL, Kapralov MV. Improving recombinant Rubisco biogenesis, plant photosynthesis and growth by coexpressing its ancillary RAF1 chaperone. PNAS (Early edition) (2015). doi: 10.1073/pnas.1420536112
Press release available at: http://www.eurekalert.org/pub_releases/2015-03/anu-spo030215.php