Redesigning the photosynthetic light reactions to enhance photosynthesis – the PhotoRedesign consortium

Abstract

SUMMARY In this Perspective article, we describe the visions of the PhotoRedesign consortium funded by the European Research Council of how to enhance photosynthesis. The light reactions of photosynthesis in individual phototrophic species use only a fraction of the solar spectrum, and high light intensities can impair and even damage the process. In consequence, expanding the solar spectrum and enhancing the overall energy capacity of the process, while developing resilience to stresses imposed by high light intensities, could have a strong positive impact on food and energy production. So far, the complexity of the photosynthetic machinery has largely prevented improvements by conventional approaches. Therefore, there is an urgent need to develop concepts to redesign the light‐harvesting and photochemical capacity of photosynthesis, as well as to establish new model systems and toolkits for the next generation of photosynthesis researchers. The overall objective of PhotoRedesign is to reconfigure the photosynthetic light reactions so they can harvest and safely convert energy from an expanded solar spectrum. To this end, a variety of synthetic biology approaches, including de novo design, will combine the attributes of photosystems from different photoautotrophic model organisms, namely the purple bacterium Rhodobacter sphaeroides, the cyanobacterium Synechocystis sp. PCC 6803 and the plant Arabidopsis thaliana. In parallel, adaptive laboratory evolution will be applied to improve the capacity of reimagined organisms to cope with enhanced input of solar energy, particularly in high and fluctuating light.

Genetics as a key to improving crop photosynthesis

“…Breeding for elite cultivars has largely ignored improvements in photosynthesis. While promising advances in improved photosynthesis may be achieved by genetic modification ( Ort et al , 2015 ; Hitchcock et al , 2022 ), we argue that using natural genetic variation for photosynthesis holds an equally promising potential for improvement. While biotechnology applications largely focus on the core photosynthetic pathway, natural genetic variation will reveal the benefit of knowledge on the thousands of genes that ensure proper embedding of photosynthesis in plant metabolism and growth.…”

A Year at the Forefront of Engineering Photosynthesis

“…In addition, although photoprotective mechanisms prevent damage to the photosystems at saturating light levels, slow downregulation of these processes can limit photosynthetic efficiency ( Kromdijk et al, 2016 ). These limitations to photosynthesis could be overcome by (i) engineering pigments/light-harvesting complexes to access a wider range of the solar spectrum, for example as proposed by the PhotoRedesign consortium ( Hitchcock et al, 2021 ), and (ii) improving the efficiency of protective mechanisms.…”

Enhancing the spectral range of plant and bacterial Light-Harvesting pigment-protein complexes with various synthetic chromophores incorporated into lipid vesicles

“…Instead, a particular LH complex will contain multiple copies of a few specific pigment types, with these arranged via precise protein-pigment interactions, resulting in a characteristic absorption spectrum. Such spectra reveal the wavelengths of light where absorption is highly effective but also highlight the “spectral gaps” where there is minimal light absorption for any given LH complex [7, 8]. Strong dipole-dipole and energetic coupling between closely-spaced (B)Chl molecules can allow excitation energy to be delocalised across multiple pigments and promote highly efficient transfer of excitation energy within the network of LH and RC protein complexes [9].…”