Our Research

Research Focused on Reserve Polysaccharide Biology

The IBSP team (Integrative Biology of Reserve Polysaccharides) aligns its work with the strategic axis “Energy Storage Polysaccharides” championed by the UGSF unit for the 2026–2030 period. Our research aims to elucidate the metabolism, structure, and regulation of reserve polysaccharides, particularly starch, to explore their evolutionary diversity, and to understand their response to abiotic stresses such as temperature or light.
This work is particularly relevant in the context of ecological, food, and energy transition, where polysaccharides are expected to play a major role in food security, the valorization of plant biomass, and the development of sustainable biomaterials.
The IBSP team’s work is structured around four major fundamental biological questions, which form the foundation of our scientific approach.

In parallel, we develop cross-cutting and exploratory projects, with a strong technological or interdisciplinary component, which enrich our understanding and open up new application perspectives.

1 / Initiation of Starch Synthesis

This process involves both the de novo synthesis of carbohydrate chains (priming) and their spatial organization (nucleation) to form a semi-crystalline granule. We study the proteins involved in these early stages. Our approach is based on a diversity of biological models, including storage organs (tubers, seeds) from cultivated species such as potato or pea, as well as green and red algae, and photosynthetic protists. For this, we utilize tools from functional genomics, multi-omics analyses, phylogeny, and comparative biochemistry.

2 / Polysaccharide Phase Transition

This is the conversion of soluble glucans into semi-crystalline starch. This complex phenomenon involves debranching enzymes (DBE), as well as non-enzymatic proteins such as LESV and ESV1, whose functions are still partly unknown. We also study algal models such as Chromera velia, which exhibit alternative crystallization pathways without classical DBE. This research integrates Raman and FT-IR imaging, structural biochemistry, genome editing (CRISPR-Cas9), and analysis of individual starch granules, to characterize the composition and fine organization of polysaccharides.

3 / Influence of Abiotic Stresses on Starch Metabolism.

Temperature is a major environmental signal, modulating photosynthesis, storage, and mobilization of carbon reserves. Our models, such as potato, pea, and certain marine microalgae, allow us to study phenomena such as “cold-induced sweetening,” dormancy and germination mechanisms, or metabolic adaptations under extreme conditions. We combine multi-omics analyses (transcriptomics, proteomics, metabolomics), biochemical, and genetic approaches to identify the regulatory networks involved; these approaches are coupled with the use of statistical tools (i.e., the mixOmics R package).

4 / Role of Pyrenoidal Starch in Marine Photosymbioses

In certain microalgae, starch accumulates around the pyrenoid, a subcellular structure that concentrates CO2 around Rubisco. We study this particular organization using the Symsagittifera roscoffensis–Tetraselmis convolutae model, by analyzing isotopic carbon fluxes (¹³C), photosynthesis in situ, and reconstituted symbioses from mutant algae generated by CRISPR. This approach allows for a better understanding of the role of starch in the stability and efficiency of alga–animal associations.

Our Cross-Cutting Projects

In parallel with these four biological questions, IBSP conducts a set of cross-cutting and interdisciplinary projects that enrich and extend these themes.

Notably, we have developed a project on “single-grain omics” (SinGraMics), in collaboration with the MSAP unit, to analyze the protein, lipid, phosphorus, and carbohydrate composition of each starch granule.
We also conduct metabolic engineering work in marine cyanobacteria within the framework of the ANR EPPIC project, to produce dextran-type polysaccharides under phototrophic conditions.
Other projects aim to characterize protein–starch interactions, in partnership with the industrial laboratory Axomama (Florimond Desprez, Germicopa, SES Vanderhave), or to develop new technological tools.
These include:
– microalgae photoporation (PhLAM),
– non-invasive microwave sugar measurement (IEMN, IRCICA),
– encapsulation of therapeutic peptides in starch granules (IEMN),
– and advanced electrophoretic analysis methods for carbohydrate polymers (IPCM).
Cross-cutting projects are carried out in collaboration with the Advanced Spectroscopy Platform of the Chevreul Institute (Lille, FR2638) and LASIRE (U-Lille, UMR CNRS 8516).
Vibrational micro-spectroscopy approaches (RAMAN or FT-IR) are developed and optimized on our models. Two major projects are thus explored: the diversity of microalgae (and among them, the identification of those that perform photosymbiosis), as well as the spectral characterization and chemical mapping of potato starch granules.

All this data is then processed using multivariate statistical approaches (PCA, PLS-DA, sPLS-DA, hierarchical clustering..).