Engineering Natural Variation in PsbS Sequence to Enhance Photosynthetic Efficiency under Fluctuating Light

Global food security is under increasing threat as climate change and population growth demand sustainable gains in crop productivity. Enhancing photosynthetic efficiency represents a transformative solution, yet the protective process of non-photochemical quenching (NPQ) remains a major bottleneck under fluctuating light. This proposal (EngNPQ) aims to optimize NPQ regulation in crops by targeting the Photosystem II subunit S (PsbS), a thylakoid protein that governs NPQ dynamics and exhibits substantial natural variation across photosynthetic lineages. The originality of EngNPQ is to link natural PsbS sequence variation to functional outcomes and use this knowledge to design protein variants that accelerate NPQ relaxation and improve light-use efficiency. To achieve this, I will characterize eleven natural PsbS variants in Arabidopsis thaliana npq4-1 mutant and Marchantia polymorpha PsbS knockout transgenic lines, employ chimeric protein design and targeted mutagenesis to identify key structural determinants, and translate these findings into tomato through CRISPR-based genome editing. This integrative approach combines comparative genomics, structural modeling, synthetic biology, and advanced phenotyping. The results will yield fundamental insights into the molecular regulation of photoprotection and provide practical tools for engineering photosynthetic traits in crops. The fellowship will also equip me with advanced expertise in genome editing and translational plant biotechnology, while expanding my profile in photophysiology. The University of Cambridge, under the supervision of Prof. Johannes Kromdijk, offers the ideal environment for this work. The outcomes will directly support the European Green Deal and UN Sustainable Development Goals, positioning Europe at the forefront of sustainable agricultural innovation, with potential applications in crop improvement, resource-efficient farming, and agricultural biotechnology.