PNNL

Abstract

The potential of enhanced photosynthetic efficiency to help achieve the sustainable yield increases required to meet future demands for food and energy (1-5) has spurred intense research towards understanding, modeling and engineering photosynthesis for enhanced crop productivity under diverse environmental conditions (4, 6-11). We posit that, alongside these current efforts, largely focused on Arabidopsis thaliana and crop plants, there is an unmet need for novel and bold paradigms in photosynthesis research. This need can be most efficiently achieved by using model systems closely related to our food, feed and energy crops and that allow rapid design-test-learn cycles. In this perspective article, we advocate for a concerted effort to accelerate our understanding and ability to redesign carbon uptake, allocation and utilization. We propose two specific research directions that combine enhanced photosynthesis with climate-smart metabolic attributes: 1) Increasing rhizospheric sink strength for carbon utilization, including strategies that allow for augmented transport of carbon to the soil for improved soil properties and carbon storage without jeopardizing aboveground crop biomass; 2)Expansion of C4 photosynthesis among crops plants and with enhanced properties, including facultative C3/C4 metabolism where a plant operates either C3 or C4 photosynthesis based on temperature and other environmental variables. We argue that this ambitious undertaking be first approached and demonstrated by exploring the full genomic potential of two model plants, the C3 grass Brachypodium distachyon and the C4 grass Setaria viridis. We see our outlook on future needs for climate-smart crops in the context of providing solutions for increased crop productivity as well as a negative-emissions technology for atmospheric CO2.