Increasing Crop Productivity by Engineering Improved Photosynthetic Efficiency

Improvement in the yield of some of our major food and feed crops has stagnated in the 21^st Century, raising doubts as to whether anticipated global food demands of mid-century could be met. Failing to meet these demands will adversely affect the poorest communities on the planet, while incentivizing expansion of cropping onto more land and furthering forest destruction. Genetic improvement of crops, and development of improved management for these new cultivars, were at the core of the Green Revolution and ability to raise more food from the land we were already using. However, the key crop characters improved during that Revolution are now reaching their biological maxima in our major food crops, making further yield gains difficult to achieve. To insure against the possibility of future food shortages, new innovations are needed, and needed now. Even if shown successful at the experimental level today, achieving regulatory compliance, environmental testing and multiplication mean that such innovations would not be available to farmers at scale for 20 years. One area where almost no improvement has been achieved over the past 50 years is in crop photosynthetic efficiency. The efficiency of conversion of solar energy into biomass by crop photosynthesis falls well below its theoretical maximum, representing an apparent opportunity for considerable yield gains. The last 50 years of research into the process has given such detail that the whole process of over 100 steps can be faithfully represented mathematically as a system of differential equations and simulated in high performance computing using numerical integration. Application of optimization routines to this system has indicated how alteration of investment in different points in the process could increase efficiency, under current and future climatic conditions. Most importantly, some of these improvements engineered in silico have now been successfully engineered in vivo, leading to increased photosynthetic efficiency and critically to increased productivity of crops in experimental field trials. Increases have also been successfully engineered for simulated climate change conditions. Building on these successful tests of concept in improving crop photosynthetic efficiency could not only help insure that we sustainably meet future food demand, but also greatly increase the viability of fuels from second generation sustainable bioenergy crops, with major environmental benefits. Evidence for these claims will be presented.