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Sorghum is the world's 5th most important grain crop. Its ability to cope with biotic and abiotic constraints could allow it to contribute to global food security in the context of climate change. However, the low digestibility of the grain reserve proteins (called kafirins) by gastrointestinal proteases is hampering its wider use for food and feed. The structure of the protein bodies in which are stored the kafirins is potentially responsible of this defect. The molecular mechanisms underlying the development and modification of kafirin-containing protein bodies are still largely unknown. In this context, our objective is to decipher the molecular mechanisms involved in the regulation of the content and digestibility of sorghum grain reserve proteins. The evolution of the transcriptome was monitored during the grain development of the Macia genotype, and supplemented by an analysis of gene co-expression networks (GCN). In parallel, the protein content of the grains and their in vitro digestibility were measured. Analyses of allowed the identification of transcription factors (TFs) potentially regulating the mechanisms of protein reserve establishment. We identified co-expression modules involving kafirin genes and genes orthologs to TFs already known in maize, rice and arabidopsis. In those modules, we also identified not yet identified TFs. In the future, we plan to evaluate the role of these TFs by a simplified cellular overexpression system in sorghum protoplasts.

Le sorgho est la 5ème céréale mondiale pour la production de grains. Sa capacité à faire face aux contraintes biotiques et abiotiques pourrait contribuer à la sécurité alimentaire du globe dans un contexte de changement climatique. Cependant, la faible digestibilité des protéines de réserves du grain (appelées kafirines) par les protéases gastro-intestinales représente un frein à sa plus large utilisation pour l'alimentation animale et humaine. Elle serait potentiellement due aux structures de stockage de ces protéines (corps protéiques). Les mécanismes moléculaires sous-jacents à la mise en place et aux modifications des corps protéiques contenant les kafirines sont encore peu connus. Dans ce contexte, notre objectif est de décrypter les mécanismes moléculaires impliqués dans la régulation de la teneur et de la digestibilité des protéines de réserve du grain de sorgho. Un suivi de l'évolution du transcriptome a été réalisé sur les grains de la variété Macia au cours de leur développement, et complété d'une analyse de réseaux de co-expession génique (RG). En parallèle, à travers des mesures de la teneur en protéine des grains et leur digestibilité in vitro, les vitesses d'accumulation des protéines (VAP) et de perte de digestibilité (VPD) ont été calculées au cours du développement du grain. Les résultats issus des RG ont permis d'identifier des modules de co-expression génique fortement corrélés à la VAP et à la VPD. L'exploration de ces modules a permis de mettre en évidence un module impliquant une grande majorité des gènes de synthèse des kafirines et des orthologues de facteurs de transcription (FT) déjà connus chez d'autres espèces et potentiellement régulateurs des mécanismes de mise en place de réserves protéiques. De nouveaux FT ont été également identifiés dans ces modules. Pour la suite, nous envisageons d'évaluer le rôle de ces FT par un système de surexpression dans des protoplastes.

The potential of sorghum to cope with biotic and abiotic constraints could enable it to contribute to global food security in the context of climate change. However, the low digestibility of the grain reserve proteins (called kafirins) by gastrointestinal proteases is hampering its wider use for food and feed. The structure of the protein bodies in which are stored the kafirins is potentially responsible of this defect. The molecular mechanisms underlying the development and modification of kafirin-containing protein bodies are still largely unknown. In this context, our objective is to decipher the molecular mechanisms involved in the regulation of the content and digestibility of sorghum grain reserve proteins. The evolution of the transcriptome was monitored during the grain development of the Macia genotype, and supplemented by an analysis of gene co-expression networks (GCN). In parallel, the protein content of the grains and their in vitro digestibility were measured. Analyses of GCN allowed the identification of transcription factors (TFs) potentially regulating the mechanisms of protein reserve establishment. We identified coexpression modules involving kafirin genes and genes orthologs to TFs already known in maize, rice and arabidopsis. In those modules, we also identified not yet identified TFs. In the future, we plan to evaluate the role of these TFs by a simplified cellular overexpression system in sorghum protoplasts. We will also investigate variability of protein content and digestibility in a panel representing sorghum worldwide genetic diversity and European commercial offer, in order to perform GWAS analyses and phenomic and genomic predictions.

The NitroSorg project is funded by CASDAR, Ministère de l'Agriculture et de l'Alimentation, France. It involves INRAE and CIRAD through the participation of the AGAP, IATE, BOA research units and the PEAT Experimental Unit, the Eurosorgho and RAGT2n seed companies, and the technical institute ITAVI. Although the SELMET research unit does not benefit directly of financial support of the project, it provides its expertise on feed quality phenotyping tools to the consortium. Nitrosorg will begin in 2022 and will last 42 months. It brings together a multidisciplinary consortium of biologists, geneticists, breeders, biochemists and poultry feed specialists to better understand the establishment of sorghum grain quality for poultry feeding and contribute to the development of breeding tools to optimize breeding efficiency for this target. Indeed, the low digestibility of sorghum grain proteins by gastrointestinal proteases, which has the particularity of decreasing even further after cooking, represents an important obstacle to a wider use of sorghum for feed but also for human nutrition. This low digestibility can be attributed to the interaction of proteins with other grain compounds such as starch or tannins, but is mainly related to the structure and properties of the storage proteins of sorghum grain (kafirins). One of the objectives of this project is to develop high-throughput characterization tools for the protein content and digestibility, but also starch and tannin content and endosperm texture that can affect this digestibility. The consortium will mobilize these tools to characterize the current European varietal offer, a panel representing the worldwide diversity, and the parental lines of the partner's breeding programs. Finally, we will carry, on a smaller panel of genotypes, an analysis of kafirin composition, and an exhaustive analysis of in vitro and in vivo protein digestibility (as part of poultry feeding). These analyses should allow us to assess the

The NitroSorg project is funded by CASDAR, Ministère de l'Agriculture et de l'Alimentation, France. It involves INRAE and CIRAD through the participation of the AGAP, IATE, BOA research units and the PEAT Experimental Unit, the Eurosorgho and RAGT2n seed companies, and the technical institute ITAVI. Although the SELMET research unit does not benefit directly of financial support of the project, it provides its expertise on feed quality phenotyping tools to the consortium. Nitrosorg will begin in 2022 and will last 42 months. It brings together a multidisciplinary consortium of biologists, geneticists, breeders, biochemists and poultry feed specialists to better understand the establishment of sorghum grain quality for poultry feeding and contribute to the development of breeding tools to optimize breeding efficiency for this target. Indeed, the low digestibility of sorghum grain proteins by gastrointestinal proteases, which has the particularity of decreasing even further after cooking, represents an important obstacle to a wider use of sorghum for feed but also for human nutrition. This low digestibility can be attributed to the interaction of proteins with other grain compounds such as starch or tannins, but is mainly related to the structure and properties of the storage proteins of sorghum grain (kafirins). One of the objectives of this project is to develop high-throughput characterization tools for the protein content and digestibility, but also starch and tannin content and endosperm texture that can affect this digestibility. The consortium will mobilize these tools to characterize the current European varietal offer, a panel representing the worldwide diversity, and the parental lines of the partner's breeding programs. Finally, we will carry, on a smaller panel of genotypes, an analysis of kafirin composition, and an exhaustive analysis of in vitro and in vivo protein digestibility (as part of poultry feeding). These analyses should allow us to assess the

Natura/ and synthetic poly(cis-1,4-isoprene) were characterized by size exclusion chromatography coupled with an online multiangle light scattering detector (SEC-MALS) (Fig. 1). Different from SEC classic method, the absolute molar masses are directly determined according to the variation of scattered light intensities with detecting angles and by using Zimm plot method for zero-angle extrapolation. This technique allows us to obtain elution profiles of rubber samples. (Texte intégral)

This is the peer reviewed version of the following article: Angellier¿Coussy, H., Torres¿Giner, S., Morel, M. H., Gontard, N., & Gastaldi, E. (2008). Functional properties of thermoformed wheat gluten/montmorillonite materials with respect to formulation and processing conditions. Journal of applied polymer science, 107(1), 487-496, which has been published in final form at https://doi.org/10.1002/app.27108. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.", [EN] Wheat gluten (WG)/montmorillonite (MMT) films were prepared by a thermomechanical process consisting of first mixing the components in a two-blade, counter-rotating device and second thermoforming the obtained dough. A significant loss in protein solubility due to the formation and rearrangement of disulfide bonds was observed upon mixing and thermoforming. In the range of studied glycerol contents (25-42.8 wt %), it was shown that glycerol had no significant effect on the mechanical properties or water sensitivity of WG-based films. Increasing the thermoforming temperature from 60 to 120 degrees C led to considerable improvements of the mechanical properties (increases in both the stress and strain at break) and a significant reduction of the water sensitivity. The introduction of MMT (up to 5 wt %) allowed the achievement of mechanical properties that were not possible by just the variation of the glycerol content and the processing temperature.

Natura/ and synthetic poly(cis-1,4-isoprene) were characterized by size exclusion chromatography coupled with an online multiangle light scattering detector (SEC-MALS) (Fig. 1). Different from SEC classic method, the absolute molar masses are directly determined according to the variation of scattered light intensities with detecting angles and by using Zimm plot method for zero-angle extrapolation. This technique allows us to obtain elution profiles of rubber samples. (Texte intégral)