Impact des génotypes de blé sur le métabolisme secondaire des Pseudomonas et conséquences sur leurs interactions avec la plante hôte

The plant root adhering soil houses an important microbial community. Roots exude a wide variety of secondary metabolites able to attract and/or control a large diversity of microbial species. In return, among the root microbiota, some bacteria are able to promote plant development, using plant growth-promotion and plant protection properties. These bacteria are named PGPR for Plant Growth-Promoting Rhizobacteria. Some PGPR belong to the Pseudomonas genus. Pseudomonas are known to produce a wide diversity of secondary metabolites that could have biological activity on the host plant and other soil microorganisms. But yet, the impact of lifetyle and host plant on Pseudomonas secondary metabolism is still poorly understood. The aim of our project is to better understand the impact of plant-bacteria interactions on organisms physiology and highlight chemical mediators of these interactions. For that, a metabolomic approach was developed in order to characterize plant-bacteria interactions between three wheat genotypes and five different fluorescent Pseudomonas strains. Work realized during this thesis allowed to characterize the impact of bacterial lifestyle and plant-bacteria interactions on physiology and plant-beneficial properties of Pseudomonas. Our data highlight specific points that had to be considered for PGPR utilization in agriculture. They also allowed to identify chemical mediators of wheat-Pseudomonas interaction. They constitute a first step and lead to numerous perspectives in order to characterize biological activities of chemical mediators, but also use this approach to study the interaction between other organisms.Le sol adhérant aux racines des plantes abrite une communauté bactérienne importante et diversifiée. La plante libère, en effet, au niveau de ses racines, des exsudats qui vont sélectionner des bactéries capables de les utiliser. En retour, certaines bactéries sont capables d’entretenir des relations de coopération avec la plante, en stimulant sa croissance et en la protégeant contre des pathogènes. Ces bactéries phytobénéfiques dites PGPR (Plant Growth-Promoting Rhizobacteria) peuvent également interagir entre elles au sein de la communauté. Le double objectif de ces travaux de thèse, a été de développer une approche métabolomique pour étudier l’impact du mode de vie et des interactions plante-bactéries sur la physiologie des organismes et mettre en évidence des médiateurs chimiques de l’interaction. Pour répondre à cet objectif, notre étude a été réalisée sur deux organismes modèles, le blé tendre (Triticum aestivum L.) et des souches bactériennes appartenant au groupe des Pseudomonas fluorescents. Les travaux réalisés au cours de cette thèse ont permis une caractérisation de l’impact du mode de vie et des interactions sur la physiologie et l’expression des propriétés phytobénéfiques des Pseudomonas. Ils ont soulevé des points concrets à prendre en compte dans l’utilisation appliquée des PGPR en agriculture et ont également mis en évidence plusieurs médiateurs d’interactions entre la plante et les Pseudomonas. Ils forment un point de départ à de nombreuses perspectives à la fois pour définir l’activité biologique des médiateurs mis en évidence au cours de l’étude, mais également utiliser cette approche pour étudier d’autres interactions mettant en jeux d’autres organismes

Wheat root modulation of Pseudomonas secondary metabolism and in turn consequences on the host plant

Le sol adhérant aux racines des plantes abrite une communauté bactérienne importante et diversifiée. La plante libère, en effet, au niveau de ses racines, des exsudats qui vont sélectionner des bactéries capables de les utiliser. En retour, certaines bactéries sont capables d’entretenir des relations de coopération avec la plante, en stimulant sa croissance et en la protégeant contre des pathogènes. Ces bactéries phytobénéfiques dites PGPR (Plant Growth-Promoting Rhizobacteria) peuvent également interagir entre elles au sein de la communauté. Le double objectif de ces travaux de thèse, a été de développer une approche métabolomique pour étudier l’impact du mode de vie et des interactions plante-bactéries sur la physiologie des organismes et mettre en évidence des médiateurs chimiques de l’interaction. Pour répondre à cet objectif, notre étude a été réalisée sur deux organismes modèles, le blé tendre (Triticum aestivum L.) et des souches bactériennes appartenant au groupe des Pseudomonas fluorescents. Les travaux réalisés au cours de cette thèse ont permis une caractérisation de l’impact du mode de vie et des interactions sur la physiologie et l’expression des propriétés phytobénéfiques des Pseudomonas. Ils ont soulevé des points concrets à prendre en compte dans l’utilisation appliquée des PGPR en agriculture et ont également mis en évidence plusieurs médiateurs d’interactions entre la plante et les Pseudomonas. Ils forment un point de départ à de nombreuses perspectives à la fois pour définir l’activité biologique des médiateurs mis en évidence au cours de l’étude, mais également utiliser cette approche pour étudier d’autres interactions mettant en jeux d’autres organismes.The plant root adhering soil houses an important microbial community. Roots exude a wide variety of secondary metabolites able to attract and/or control a large diversity of microbial species. In return, among the root microbiota, some bacteria are able to promote plant development, using plant growth-promotion and plant protection properties. These bacteria are named PGPR for Plant Growth-Promoting Rhizobacteria. Some PGPR belong to the Pseudomonas genus. Pseudomonas are known to produce a wide diversity of secondary metabolites that could have biological activity on the host plant and other soil microorganisms. But yet, the impact of lifetyle and host plant on Pseudomonas secondary metabolism is still poorly understood. The aim of our project is to better understand the impact of plant-bacteria interactions on organisms physiology and highlight chemical mediators of these interactions. For that, a metabolomic approach was developed in order to characterize plant-bacteria interactions between three wheat genotypes and five different fluorescent Pseudomonas strains. Work realized during this thesis allowed to characterize the impact of bacterial lifestyle and plant-bacteria interactions on physiology and plant-beneficial properties of Pseudomonas. Our data highlight specific points that had to be considered for PGPR utilization in agriculture. They also allowed to identify chemical mediators of wheat-Pseudomonas interaction. They constitute a first step and lead to numerous perspectives in order to characterize biological activities of chemical mediators, but also use this approach to study the interaction between other organisms

Wheat Metabolite Interferences on Fluorescent Pseudomonas Physiology Modify Wheat Metabolome through an Ecological Feedback

Plant roots exude a wide variety of secondary metabolites able to attract and/or control a large diversity of microbial species. In return, among the root microbiota, some bacteria can promote plant development. Among these, Pseudomonas are known to produce a wide diversity of secondary metabolites that could have biological activity on the host plant and other soil microorganisms. We previously showed that wheat can interfere with Pseudomonas secondary metabolism production through its root metabolites. Interestingly, production of Pseudomonas bioactive metabolites, such as phloroglucinol, phenazines, pyrrolnitrin, or acyl homoserine lactones, are modified in the presence of wheat root extracts. A new cross metabolomic approach was then performed to evaluate if wheat metabolic interferences on Pseudomonas secondary metabolites production have consequences on wheat metabolome itself. Two different Pseudomonas strains were conditioned by wheat root extracts from two genotypes, leading to modification of bacterial secondary metabolites production. Bacterial cells were then inoculated on each wheat genotypes. Then, wheat root metabolomes were analyzed by untargeted metabolomic, and metabolites from the Adular genotype were characterized by molecular network. This allows us to evaluate if wheat differently recognizes the bacterial cells that have already been into contact with plants and highlights bioactive metabolites involved in wheat—Pseudomonas interaction

Exploiting rhizosphere microbial cooperation for developing sustainable agriculture strategies

International audienc

A Cross-Metabolomic Approach Shows that Wheat Interferes with Fluorescent Pseudomonas Physiology through Its Root Metabolites

International audienceRoots contain a wide variety of secondary metabolites. Some of them are exudated in the rhizosphere, where they are able to attract and/or control a large diversity of microbial species. In return, the rhizomicrobiota can promote plant health and development. Some rhizobacteria belonging to the Pseudomonas genus are known to produce a wide diversity of secondary metabolites that can exert a biological activity on the host plant and on other soil microorganisms. Nevertheless, the impact of the host plant on the production of bioactive metabolites by Pseudomonas is still poorly understood. To characterize the impact of plants on the secondary metabolism of Pseudomonas, a cross-metabolomic approach has been developed. Five different fluorescent Pseudomonas strains were thus cultivated in the presence of a low concentration of wheat root extracts recovered from three wheat genotypes. Analysis of our metabolomic workflow revealed that the production of several Pseudomonas secondary metabolites was significantly modulated when bacteria were cultivated with root extracts, including metabolites involved in plant-beneficial properties

Sustainable isolation and improved structural characterization of mycosporin-like amino acids: natural UV-filters from red algae

International audienceMycosporin-like amino acids (MAAs) are low-molecular-weight, colorless and water-soluble compounds produced by a wide variety of marine organisms including corals, fungi, algae and cyanobacteria (Geraldes and Pinto, 2021). They are recognized as a potential source of naturalsunscreens due to their capacity to absorb a very large proportion of UV rays. MAAs are also characterized by other biological activities such as antioxidant, anti-aging and anti-inflammatory properties (Rosic, 2021) (Fonsesca et al., 2023). MAAs are thus of growing interest for their capacity to replace controversial photoprotective agents in sunscreen products. Nevertheless, their enrichment or isolation remain a challenge in cosmetic industry. This presentation will cover the development of a sustainable purification strategy of MAAs that can be easily transposed to an industrial scale. In this context, centrifugal partition chromatography (CPC) using aqueous two-phase system was particularly adapted to isolateMAAs (Michel et al. 2023). The developed method allowed to obtain pure compounds and enriched fraction from a Porphyra sp. crude extract. Structure elucidation employing extensive NMR spectroscopy and HRMS allowed the identification of MAAs such as Porphyra-334.This work provides a new approach, easily scalable, to produce enriched cosmetical ingredients or to purify MAAs that can be used in diverse formulation to enhance the efficacy of natural sunscreens

Sustainable isolation and improved structural characterization of mycosporin-like amino acids: natural UV-filters from red algae

International audienceMycosporin-like amino acids (MAAs) are low-molecular-weight, colorless and water-soluble compounds produced by a wide variety of marine organisms including corals, fungi, algae and cyanobacteria (Geraldes and Pinto, 2021). They are recognized as a potential source of naturalsunscreens due to their capacity to absorb a very large proportion of UV rays. MAAs are also characterized by other biological activities such as antioxidant, anti-aging and anti-inflammatory properties (Rosic, 2021) (Fonsesca et al., 2023). MAAs are thus of growing interest for their capacity to replace controversial photoprotective agents in sunscreen products. Nevertheless, their enrichment or isolation remain a challenge in cosmetic industry. This presentation will cover the development of a sustainable purification strategy of MAAs that can be easily transposed to an industrial scale. In this context, centrifugal partition chromatography (CPC) using aqueous two-phase system was particularly adapted to isolateMAAs (Michel et al. 2023). The developed method allowed to obtain pure compounds and enriched fraction from a Porphyra sp. crude extract. Structure elucidation employing extensive NMR spectroscopy and HRMS allowed the identification of MAAs such as Porphyra-334.This work provides a new approach, easily scalable, to produce enriched cosmetical ingredients or to purify MAAs that can be used in diverse formulation to enhance the efficacy of natural sunscreens

Sustainable isolation and improved structural characterization of mycosporin-like amino acids: natural UV-filters from red algae

International audienceMycosporin-like amino acids (MAAs) are low-molecular-weight, colorless and water-soluble compounds produced by a wide variety of marine organisms including corals, fungi, algae and cyanobacteria (Geraldes and Pinto, 2021). They are recognized as a potential source of naturalsunscreens due to their capacity to absorb a very large proportion of UV rays. MAAs are also characterized by other biological activities such as antioxidant, anti-aging and anti-inflammatory properties (Rosic, 2021) (Fonsesca et al., 2023). MAAs are thus of growing interest for their capacity to replace controversial photoprotective agents in sunscreen products. Nevertheless, their enrichment or isolation remain a challenge in cosmetic industry. This presentation will cover the development of a sustainable purification strategy of MAAs that can be easily transposed to an industrial scale. In this context, centrifugal partition chromatography (CPC) using aqueous two-phase system was particularly adapted to isolateMAAs (Michel et al. 2023). The developed method allowed to obtain pure compounds and enriched fraction from a Porphyra sp. crude extract. Structure elucidation employing extensive NMR spectroscopy and HRMS allowed the identification of MAAs such as Porphyra-334.This work provides a new approach, easily scalable, to produce enriched cosmetical ingredients or to purify MAAs that can be used in diverse formulation to enhance the efficacy of natural sunscreens

Profiling of ob/ob mice skeletal muscle exosome-like vesicles demonstrates combined action of miRNAs, proteins and lipids to modulate lipid homeostasis in recipient cells

We have determined the lipid, protein and miRNA composition of skeletal muscle (SkM)-released extracellular vesicles (ELVs) from Ob/ob (OB) vs wild-type (WT) mice. The results showed that atrophic insulin-resistant OB-SkM released less ELVs than WT-SkM, highlighted by a RAB35 decrease and an increase in intramuscular cholesterol content. Proteomic analyses of OB-ELVs revealed a group of 37 proteins functionally connected, involved in lipid oxidation and with catalytic activities. OB-ELVs had modified contents for phosphatidylcholine (PC 34-4, PC 40-3 and PC 34-0), sphingomyelin (Sm d18:1/18:1) and ceramides (Cer d18:1/18:0) and were enriched in cholesterol, likely to alleviated intracellular accumulation. Surprisingly many ELV miRNAs had a nuclear addressing sequence, and targeted genes encoding proteins with nuclear activities. Interestingly, SkM-ELV miRNA did not target mitochondria. The most significant function targeted by the 7 miRNAs altered in OB-ELVs was lipid metabolism. In agreement, OB-ELVs induced lipid storage in recipient adipocytes and increased lipid up-take and fatty acid oxidation in recipient muscle cells. In addition, OB-ELVs altered insulin-sensitivity and induced atrophy in muscle cells, reproducing the phenotype of the releasing OB muscles. These data suggest for the first time, a cross-talk between muscle cells and adipocytes, through the SkM-ELV route, in favor of adipose tissue expansion