The capability of plant cells to capture CO₂ and convert inorganic carbon into sugars, starch, biomolecules and even high value metabolites, means they can be viewed as powerful, sustainable factories. However, their full potential for carbon assimilation is often limited by how carbon is sensed, allocated and used in biosynthetic processes and growth. In this project, we propose to rewire this regulatory logic to boost carbon allocation in plant cells, thereby enhancing their growth and capacity to serve as living manufacturing platforms.

Our approach builds on the signalling network underlying plant sucrose homeostasis by coupling sucrose availability to anabolic processes and growth. In nature, this system helps balance carbon supply and demand, ensuring that carbon is distributed appropriately among competing non-photosynthetic organs. We will repurpose this signalling network to finetune carbon partitioning in plant cell cultures. Specifically, we will manipulate the levels of trehalose 6-phosphate (T6P), a signalling metabolite that regulates carbon utilization, through rational engineering of the enzymes responsible for T6P synthesis and degradation. By designing enzyme variants that moderately increase or decrease T6P levels, we aim to stimulate growth and biosynthetic capacity while minimising side effects such as metabolic imbalance or accelerated senescence. Proof-of-concept will be established in Arabidopsis thaliana cell cultures, leveraging their genetic tractability; however, because this signalling network is highly conserved, this strategy can ultimately be transferred to other species and production platforms.

The project will combine structure-guided enzyme engineering, enzymatic assays with recombinant proteins, AI-assisted variant design and CRISPR-based prime editing to create and test enzyme variants with defined effects on T6P turnover. Engineered cell cultures will be phenotyped for growth, biomass accumulation and carbon allocation, and analyzed using cell phenotyping, molecular readouts of cell growth/stress responses, and omics approaches. If successful, this work will establish a general framework for controlling carbon allocation in plant cells. In the future, these principles could be extended to whole plants and different species, enhancing carbon flux and usage in key organs