Enhancing crops with C2 photosynthesis

Our food security is at risk. Within the next 30-years, the human population is expected to reach nearly 10 billion, requiring a doubling of crop production. However, the current trajectory of crop yield improvements will not meet these needs, making new agricultural innovations paramount to ensure future food security.

Improving photosynthetic efficiency is a promising, yet largely untapped route to enhance crop yields. Our dominant crops (e.g., rice, wheat) use C3 photosynthesis, such that any improvement to this system would substantially impact food security. Under warm, arid, and bright environments, C3 plants suffer from an energetically-costly metabolic process called photorespiration.

Photorespiration is a major factor limiting productivity in C3 plants and it will only get worse with the warm temperatures accompanying climate change. If we could find a way to eliminate photorespiration therefore, we could more than double rates of photosynthesis under climate change. However, eliminating photorespiration all together would impact other plant metabolic functions.

Therefore, the ideal scenario would be to find a way to maintain photorespiration but minimise its carbon losses. Engineering C2 photosynthesis into C3 crops is the clear solution.

C2 photosynthesis is a simple CO2 concentrating mechanism that captures, concentrates, and re-assimilates CO2 released by photorespiration. It is, in short, a natural CO2 recycling mechanism. Although only recently discovered in the early 1980s, the C2 mode of photosynthesis has repeatedly evolved across diverse plant lineages, including four crop families (Poaceae, Brassicaceae, Asteraceae, Amaranthaceae).

This FLF will establish the world's first research program specifically dedicated to engineering the rare C2 mode of photosynthesis into important C3 food and bioenergy crops to sustainably improve yield and environmental resilience. Because all of the genes required for C2 photosynthesis are present in C3 species, only changes to regulation and expression would be needed to engineer C2 photosynthesis into C3 crops.

Moreover, C2 plants also have similar leaf structures to C3 plants, which simplifies the engineering protocol. Together, this FLF will initiate a robust research program to establish an impactful, yet feasible, C2 crop engineering and commercialisation strategy via seven work packages: 1. Identify the phenotypic components of C2 photosynthesis in diverse plant families

2. Map the spatial gene expression profiles of C2 leaves across three diverse crop families 3. Engineer a functional C2 photosynthesis system into three C3 Brassicaceae crops 4. Design C2 engineering packages specific to three diverse crop families 5. Field trial the engineered C2 Brassica germplasm

6. Commercialise C2 Brassica products 7. Initiate C2 transformations in Amaranthaceae and Asteraceae crops

Together, the proposed innovative research program will launch an impactful novel crop improvement program aimed to increase yields and stability under our future unstable climate.