DS05 - Sécurité alimentaire et défi démographique

Tailoring potato starch in vivo to support emerging bio-based sectors – TaPStar

Submission summary

Starch is a storage form of carbohydrates in plants and the main source of calories in human and animal diets. Moreover, this polymer is used in many industrial applications for food and non-food purpose. During the last decades, it became a major renewable raw material for manufacturing products such as plastics and paints. These materials are agrobased, potentially biodegradable and thus are of great interest in a context of ecological transition. Consequently, new industrial sectors are arising that rely on starch as a raw material. In the “Hauts de France” region, starch-rich crops like potato are cultivated locally and represent a valuable resource to supply these sectors, without the need for long transportation of the raw material thus limiting greenhouse gas emissions. However, starch quality determines downstream applications that often require chemical modifications. The latter are costly and will impact the carbon balance and ecological footprint of the sector. Improving starch quality in vivo (i.e. before extraction) requires the development of new plant breeding programs that take the corresponding traits into account. Phosphate groups are naturally present in starch at C3- or C6-position of the glucose residues and impact the structure of starch granules. Other locks also impact post-extraction processing, namely the size of starch granules and the structure of starch polymers.
This project aims at upgrading the knowledge regarding starch properties in vivo that are of interest in emerging starch-based industrial sectors. Moreover, the project intents to offer a phenotyping support to breeding programs targeting the new potato flour markets. In a previous work funded by ANR (PoStaTic project: Structural and morphological variability of potato starch and associated biological processes towards bio-plastic production), we have developed a semi high-throughput platform (including a new a capillary electrophoresis method to determine both C3- and C6-phosphoesters in starch) for characterizing starch structure and morphology and estimated their variability in numerous potato cultivars. Moreover, we deciphered the complete potato starch-associated proteome. In addition to the already known starch-bound proteins, we identified proteins with a high targeting potential. Interestingly, there is growing evidence that the amount of starch-bound proteins follows specific stoichiometric requirements related to starch initiation, synthesis, phosphorylation, and degradation as well as the control of granule size and number.
With this project, we ambition to: i. decipher the stoichiometry of starch-bound proteins and its impact on starch structure and morphology by quantitative proteomics of single-starch granules; ii. understand the function of new target genes in potato by reverse genetics using the CRISPR/Cas9 system; iii. determine the exact repartition of the phosphoesters within the polymers and understand how they impact the molecular organization of starch; iv. characterize the variability of starch phosphorylation and morphology in wild-type potato-related species to open new perspectives in trait introgression approaches. This project will, for the first time, lead to single starch granule characterization and allow to understand how starch-bound proteins participate to the establishment and maintenance of the granule architecture. Furthermore, it will report on the natural variability of starch in wild-type potato species, allowing for instance to provide solutions to breeding programs targeting emerging sectors. Finally, this project will result in the characterization of new gene functions related to starch metabolism. The latter will be edited in potato by CRISPR/Cas9 to provide new functional traits in one of the most cultivated crops. Future legislation regarding gene-edited plants may facilitate bioeconomical applications of these plants.

Project coordination

Nicolas Szydlowski (Unité de glycobiologie structurale et fonctionnelle)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

UGSF Unité de glycobiologie structurale et fonctionnelle

Help of the ANR 290,476 euros
Beginning and duration of the scientific project: - 36 Months

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