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iPHACTORY: Interdisciplinary study of photosynthetic glandular trichomes as metabolic cell factories

Subject Area Plant Biochemistry and Biophysics
Bioinformatics and Theoretical Biology
Term from 2019 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 420069095
 
Final Report Year 2024

Final Report Abstract

In the interdisciplinary project iPHACTORY, our team of molecular and computational biologists focused on investigating the role of photosynthesis and central carbon metabolism inside of plant epidermal outgrowths named glandular trichomes (GT). Localised on the surface of the aerial parts of plants, glandular trichomes produce, store, and secrete high amounts of a wide range of chemically diverse compounds, including terpenoids. Due to extremely high metabolic fluxes, production of some can reach up to 20% of the leaf dry weight, glandular trichomes are often referred to as true metabolic cell factories. Recent studies suggested that some trichomes are photosynthetically active, raising questions regarding how (if at all) primary metabolism contributes to the high metabolic fluxes in glandular trichomes. Using COBRA Toolbox, data from LycoCyc and MetaCyc metabolic pathway databases, and available multi-omics data, we developed a stoichiometric model of specialised metabolism in photosynthetic glandular trichomes of Solanum lycopersicum (tomato) and predicted that increasing light intensities results in a shift of carbon partitioning from catabolic to anabolic reactions driven by the energy availability of the cell. Moreover, we showed that the photosynthetic activity of the cell provides an added benefit of shifting between two isoprenoid pathways: methyl-erythritolphosphate pathway (MEP) and mevalonate pathway (MEV), under different light regimes. Thanks to the tight collaboration between the theoretical and experimental lab we could test the model-driven hypothesis regarding affected terpenoid production. Using transcriptome data from previous work, we selected a number of genes to knock-out or down to evaluate their role in the supply of precursors for the terpenoid pathways. This includes the small subunit of Rubisco, Phosphoenolpyruvate Carboxylase kinase (PEPCK), plastidial fructose bisphosphate aldolase. In addition, we also evaluated trichome productivity when plants are exposed to heat treatment (37°C). For the computational analysis we additionally expanded the number of investigated organisms to include a cyanobacterium Synechocystis, which although photosynthetically active, in contrast to tomato glandular trichomes, possesses only one terpenoid producing pathway (MEP). Finally, the project motivated development of an open source Teaching Tool in Biology on modelling in biological context and software for stoichiometric model construction by our collaborators.

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