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Title: Redesigning photosynthesis to sustainably meet global food and bioenergy demand

Author
item Ort, Donald
item MERCHANT, SABEEHA - University Of California
item ALRIC, JEAN - National Council For Scientific Research-Cnrs
item BARKAN, ALICE - University Of Oregon
item BLANKENSHIP, ROBERT - Washington University
item BOCK, RALPH - Max Planck Society
item CROCE, ROBERTA - Vrije University
item HANSON, MAUREEN - Cornell University
item LONG, STEPHEN - University Of Illinois
item MOORE, THOMAS - Arizona State University

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2015
Publication Date: 6/29/2015
Citation: Ort, D.R., Merchant, S.S., Alric, J., Barkan, A., Blankenship, R.E., Bock, R., Croce, R., Hanson, M.R., Long, S.P., Moore, T.A., et al. 2015. Redesigning photosynthesis to sustainably meet global food and bioenergy demand. Proceedings of the National Academy of Sciences. 112(28):8529-8536.

Interpretive Summary: The world’s crop productivity is stagnating while population growth, rising affluence, and mandates for biofuels put increasing demands on this resource. Meanwhile, demand for increasing cropland competes with equally crucial global sustainability and environmental protection needs. Addressing this looming agricultural crisis will be one of our greatest scientific challenges in the coming decades, and success will require substantial improvements at many levels. We assert that increasing the efficiency and productivity of photosynthesis in crop plants will be essential if this grand challenge is to be met. Here we explore an array of prospective redesigns of plant systems at various scales, all aimed at increasing crop yields through improved photosynthetic efficiency and performance. They range from straightforward alterations, already supported by preliminary evidence of feasibility, to substantial redesigns that are currently only conceptual, but which may be enabled by new developments in synthetic biology. While some are certain to face obstacles that will require alternate routes, the efforts should lead to new discoveries and technical advances with important impacts on the global problem of crop productivity and bioenergy production.

Technical Abstract: The remarkable gains in productivity of the Green Revolution of the late 20th century depended on improving yield potential, i.e. the yield obtained with good nutrition in the absence of pests, diseases and drought. To a first approximation, yield potential is dependent on the amount of solar energy available during the growing season, and the efficiencies with which the crop captures the photosynthetically active light, converts it to biomass, and partitions the biomass into the harvested product. During the Green Revolution increases in yield potential were driven primarily by large increases in the portion of biomass partitioned into grain (i.e., harvest index), which is now near its theoretical upper limit. Improved solar energy conversion efficiency has so far played little role in improving yield potential, yet photosynthesis is the only determinant that is not close to its biological limits. Fortunately there are a wide range of potential avenues to improve photosynthetic efficiency along radically different paths than those dictated by evolutionary selection on extant and emergent natural variation.