Synthetic Pathways for Enhanced Photosynthesis

"Zero Hunger" is the second of the Sustainable Development Goals of the United Nations (UN), which aims to end hunger and to ensure Food Security by 2030 [1]. Achieving this goal is confounded by an ever-increasing world population which is predicted to reach 9 billion people by 2030 [2], accompanied by an increase of calorie uptake per capita of ~0.6% per year [3] [2], such that global food production needs to increase by ~30-40% by 2030. To achieve this Food Security goal, a balance between demand and supply would have to be achieved. "Food security exists when all people, at all times, have physical and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life" [4] [5]. The reality is that we are far from achieving this goal, with more than a quarter of the world population being affected by food insecurity in 2019, global hunger increasing annually since 2015 (UN SOFI report 2020), and now with the additional influence of the current COVID-19 pandemic, having the hardest impact on smallholder farmers [1].
The challenge of providing safe and healthy food is not just confounded by the ever-increasing growth and consumption by the human population, the current climate crisis additionally aggravates the situation. Not only through the direct impact on food production, by changes in the agro-ecological conditions, but also by the indirect socioeconomic changes that contribute to a large insecurity in food supply [6]. For example, the demand for fertile farm grounds clashes with the need to change land use to forestry to reduce greenhouse gas emissions [7] [8]. This further exacerbates the challenge of feeding 9 billion people by 2030 without using more land for agriculture. Thus, innovation in multiple areas is required if the ambitious "Zero Hunger" goal of the UN is to be realized.
Increasing the yield of the world's most important food crops has the potential to help achieve Zero hunger. One of the most promising approaches to increasing crop yield, is to increase the photosynthetic efficiency of (crop-) plants [9]. Photosynthesis is the biochemical process that converts sun energy, water and CO2 to make the consumable sugars that supply energy to the entire global good chain. Photosynthesis in land plants provides almost all the calories consumed by humans as well as natural carbon sink that sequesters CO2 from the atmosphere [10] [11]. In both natural and agricultural environments plant growth is limited by multiple different factors [12]. These factors include the amount of light energy from the sun, the amount of nitrogen (and other micro nutrients) and water available in the soil, and the amount of CO2 available inside the plant leaf. The amount of sun energy is weather and latitude dependent, and the nutrient and water supply can be controlled by agricultural techniques. However, it is difficult to manipulate CO2 concentration on a large scale using agricultural techniques. The development of precise techniques for genetic engineering, and the emergence of Synthetic Biology, has opened up new avenues for enabling plants to concentrate CO3 inside cells within a leaf and this has the potential to revolutionize agricultural productivity [13].