FARED WELL · Photosynthesis in far-red: from cyanobacteria to plants

Photosynthesis, the process that sustains life on our planet by generating food and supplying oxygen, is astonishingly inefficient: less than 1% of accessible solar energy is converted into biomass by a crop. Improving photosynthesis is thus a promising approach to meet the increasing demand for food production. The capacity to optimally harness light is a crucial factor in the photosynthetic process, especially in light-limited environments. However, plants only utilize the visible part of the solar spectrum (400-700 nm), which results in more than 50% of the photons reaching the Earths surface being discarded. This represents an important limitation, especially for crops, as plants in the field are close together, and the light reaching the lower leaves is almost exclusively far-red (>700 nm). Until recently, it was believed that 700 nm was the thermodynamic limit of oxygenic photosynthesis. However, the discovery of several species of cyanobacteria, the prokaryotic ancestors of plant chloroplasts, that can grow in far-red light has shown that this is not the case. How can cyanobacteria use far-red light? Would it be possible to introduce the same mechanisms into plants to expand their spectral coverage and increase light-use efficiency? This project aims to address these questions by elucidating the mechanisms underlying far-red light acclimation in cyanobacteria and re-designing them to be compatible with the photosynthetic system of plants. This requires to address knowledge gaps related to the synthesis of novel pigments, their integration into photosynthetic proteins, and their impact on photochemical efficiency and photosynthesis regulation. For this I will combine in vivo, in vitro and in silico approaches, ranging from molecular biology to ultrafast spectroscopy and modeling, which is the trademark of my group. This project will determine if implementing a far-red response in plants is viable, beneficial, and a potential strategy for crop enhancement.