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To move today’s agricultural and urban systems towards tomorrow’s circular economy and respond to climate change, it is imperative to turn organic residues and wastewater into resourceful assets. This article discusses the changes that are needed in research to drive this paradigm shift and to go from a “losses and waste” situation to a “resource and opportunities” ambition. The current lines of research aim to maximise the use and value of biomass or organic residues and wastewater and propose new organisational schemes driven by technical innovations. Exploring the pathways to a sustainable future through many domains let us identify five challenges to structure the research efforts and find circular bioeconomy solutions for organic residues and wastewater: (1) proposing innovative processes and integrated multi-process systems; (2) promoting the emergence of multi-scale and cross-sectoral organisations; (3) developing multi-performance evaluation methods, (4) rethinking research–society intersections, and (5) enhancing research–legislation interactions. We end by outlining prospects for moving forward past current limitations: beyond increasing knowledge, research will continue its own transition. Our responsibility today is not to think about what we could do for a better world but what we should do to make our ever-changing world even better and more sustainable. Graphic Abstract

The plant cuticle is deposited on the surface of primary plant organs, such as leaves, fruits, and floral organs, forming a diffusion barrier and protecting the plant against various abiotic and biotic stresses. Cutin, the structural polyester of the plant cuticle, is synthesized in the apoplast. Plasma-membrane-localized ATP-binding cassette (ABC) transporters of the G family have been hypothesized to export cutin precursors. Here, we characterize SlABCG42 of tomato representing an ortholog of AtABCG32 in Arabidopsis. SlABCG42 expression in Arabidopsis complements the cuticular deficiencies of the Arabidopsis pec1/abcg32 mutant. RNAi-dependent downregulation of both tomato genes encoding proteins highly homologous to AtABCG32 (SlABCG36 and SlABCG42) leads to reduced cutin deposition and formation of a thinner cuticle in tomato fruits. By using a tobacco (Nicotiana benthamiana) protoplast system, we show that AtABCG32 and SlABCG42 have an export activity for 10,16-dihydroxy hexadecanoyl-2-glycerol, a cutin precursor in vivo. Interestingly, also free ω-hydroxy hexadecanoic acid as well as hexadecanedioic acid were exported, furthering the research on the identification of cutin precursors in vivo and the respective mechanisms of their integration into the cutin polymer.

International audience; Grain hardness is an important quality trait of cereal crops. In wheat, it is mainly determined by the Hardness locus that harbors genes encoding puroindoline A (PINA) and puroindoline B (PINB). Any deletion or mutation of these genes leading to the absence of PINA or to single amino acid changes in PINB leads to hard endosperms. Although it is generally acknowledged that hardness is controlled by adhesion strength between the protein matrix and starch granules, the physicochemical mechanisms connecting puroindolines and the starch-protein interactions are unknown as of this time. To explore these mechanisms, we focused on PINA. The overexpression in a hard wheat cultivar (cv. Courtot with the Pina-D1a and Pinb-D1d alleles) decreased grain hardness in a dose-related effect, suggesting an interactive process. When PINA was added to gliadins in solution, large aggregates of up to 13 μm in diameter were formed. Turbidimetry measurements showed that the PINA-gliadin interaction displayed a high cooperativity that increased with a decrease in pH from neutral to acid (pH 4) media, mimicking the pH change during endosperm development. No turbidity was observed in the presence of isolated α-and γ-gliadins, but non-cooperative interactions of PINA with these proteins could be confirmed by surface plasmon resonance. A significant higher interaction of PINA with γ-gliadins than with α-gliadins was observed. Similar binding behavior was observed with a recombinant repeated polypeptide that mimics the repeat domain of gliadins, i.e., (Pro-Gln-Gln-Pro-Tyr) 8. Taken together, these results suggest that the interaction of PINA with a monomeric gliadin creates a nucleation point leading to the aggregation of other gliadins, a phenomenon that could prevent further interaction of the storage prolamins with starch granules. Consequently, the role of puroindolineprolamin interactions on grain hardness should be addressed on the basis of previous observations that highlight the similar subcellular routing of storage prolamins and puroindolines.

The cuticle is an essential and ubiquitous biological polymer composite covering aerial plant organs, whose structural component is the cutin polyester entangled with cell wall polysaccharides. The nature of the cutin-embedded polysaccharides (CEPs) and their association with cutin polyester are still unresolved Using tomato fruit as a model, chemical and enzymatic pretreatments combined with biochemical and biophysical methods were developed to compare the fine structure of CEPs with that of the noncutinized polysaccharides (NCPs). In addition, we used tomato fruits from cutin-deficient transgenic lines cus1 (cutin synthase 1) to study the impact of cutin polymerization on the fine structure of CEPs. Cutin-embedded polysaccharides exhibit specific structural features including a high degree of esterification (i.e. methylation and acetylation), a low ramification of rhamnogalacturonan (RGI), and a high crystallinity of cellulose. In addition to decreasing cutin deposition and polymerization, cus1 silencing induced a specific modification of CEPs, especially on pectin content, while NCPs were not affected. This new evidence of the structural specificities of CEPs and of the cross-talk between cutin polymerization and polysaccharides provides new hypotheses concerning the formation of these complex lipopolysaccharide edifices.

The main storage components of the maize endosperm are starch, proteins and lipids. Starch and proteins are heterogeneously deposited, leading to the formation of vitreous and floury regions at the periphery and at the centre of the endosperm. The vitreous/floury mass ratio is a key physical parameter of maize end-uses for the food, feed and non-food sectors, as well as for the resistance of seeds to environmental aggressions. To improve maize breeding for vitreousness, one of the main issues is to finely delineate the molecular and physicochemical mechanisms associated with the formation of endosperm texture. In this context, we use scanning transmission X-ray microscopy at the C K-edge on maize endosperm resin-embedded ultrathin sections. The combination of local near edge X-ray absorption fine structure (NEXAFS) spectroscopy and high-resolution images enable us to achieve a quantitative fine description of the spatial distribution of the main components within the endosperm.

International audience; Cuticular matrices covering aerial plant organs or delimiting compartments in these organs are composed of an insoluble hydrophobic polymer of high molecular mass, i.e., cutin, that encompass some cell wall polysaccharides and is filled by waxes. Cutin is a polyester of hydroxy and-or epoxy fatty acids including a low amount of glycerol. Screening of Arabidopsis and more recently of tomato (Solanum lycopersicum) mutants allowed the delineation of the metabolic pathway involved in the formation of cutin monomers, as well as their translocation in the apoplast. Furthermore, these studies identified an extracellular enzyme involved in the polymerization of these monomers, i.e., cutin synthase 1 (CUS1), an acyl transferase of the GDSL lipase protein family. By comparing the structure of tomato fruit cutins from wild type and down-regulated CUS1 mutants, as well as with the CUS1-catalyzed formation of oligomers in vitro, hypothetical models can be elaborated on the polymerization of cutins. The polymorphism of the GDSL-lipase family raises a number of questions concerning the function of the different isoforms in relation with the formation of a composite material, the cuticle, containing entangled hydrophilic and hydrophobic polymers, i.e., polysaccharides and cutin, and plasticizers, i.e., waxes.

Improving crop productivity and quality while promoting sustainable agriculture have become major goals in plant breeding. The cuticle is a natural film covering the aerial organs of plants and consists of lipid polyesters covered and embedded with wax. The cuticle protects plants against water loss and pathogens and affects traits with strong impacts on crop quality such as, for horticultural crops, fruit brightness, cracking, russeting, netting, and shelf life. Here we provide an overview of the most important cuticle-associated traits that can be targeted for crop improvement. To date, most studies on cuticle-associated traits aimed at crop breeding have been done on fleshy fruits. Less information is available for staple crops such as rice, wheat or maize. Here we present new insights into cuticle formation and properties resulting from the study of genetic resources available for the various crop species. Our review also covers the current strategies and tools aimed at exploiting available natural and artificially induced genetic diversity and the technologies used to transfer the beneficial alleles affecting cuticle-associated traits to commercial varieties.

International audience; Relationships between kernel vitreousness and proteins and starch partitioning to the floury and vitreous regions of the endosperm were monitored in a set of 13 maize inbred lines. Decrease of protein contents from the vitreous to the floury endosperms were mainly assigned to a-zeins. Using Raman microspectroscopy, we observed a protein gradient from the periphery to the center of endosperms that well fitted with the inverse relationships between vitreousness and protein content of the vitreous and floury regions. In addition, Raman microspectroscopy highlighted an increase of starch crystallinity from the periphery to the center of the maize endosperms. This agrees with the higher amylose and associated lipid contents within starches of vitreous than in those of floury endosperms. Finally, starch granules from vitreous regions displayed more channels than the floury ones. These channels contain proteins that might favor adhesion of proteins to starch granules or granule granule contacts to form the close packing of the vitreous endosperm. Therefore transition from vitreous to floury endosperm is at least the result of both protein and starch gradients. These gradients are probably associated with metabolic gradients that have been observed during endosperm development. (C) 2016 Elsevier Ltd. All rights reserved.

International audience; Content and composition of maize endosperm lipids and their partition in the floury and vitreous regions were determined for a set of inbred lines. Neutral lipids, i.e., triglycerides and free fatty acids, accounted for more than 80% of endosperm lipids and are almost 2 times higher in the floury than in the vitreous regions. The composition of endosperm lipids, including their fatty acid unsaturation levels, as well as their distribution may be related to metabolic specificities of the floury and vitreous regions in carbon and nitrogen storage and to the management of stress responses during endosperm cell development. Remarkably, the highest contents of starch lipids were observed systematically within the vitreous endosperm. These high amounts of starch lipids were mainly due to lysophosphatidylcholine and were tightly linked to the highest amylose content. Consequently, the formation of amyloselysophosphatidylcholine complexes has to be considered as an outstanding mechanism affecting endosperm vitreousness.

International audience; The cutin polymers of different fruit cuticles (tomato, apple, nectarine) were examined using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) after in situ release of the lipid monomers by alkaline hydrolysis. The mass spectra were acquired from each coordinate with a lateral spatial resolution of approximately 100m. Specific monomers were released at their original location in the tissue, suggesting that post-hydrolysis diffusion can be neglected. Relative quantification of the species was achieved by introducing an internal standard, and the collection of data was subjected to non-supervised and supervised statistical treatments. The molecular images obtained showed a specific distribution of ions that could unambiguously be ascribed to cutinized and suberized regions observed at the surface of fruit cuticles, thus demonstrating that the method is able to probe some structural changes that affect hydrophobic cuticle polymers. Subsequent chemical assignment of the differentiating ions was performed, and all of these ions could be matched to cutin and suberin molecular markers. Therefore, this MALDI-MSI procedure provides a powerful tool for probing the surface heterogeneity of plant lipid polymers. This method should facilitate rapid investigation of the relationships between cuticle phenotypes and the structure of cutin within a large population of mutants.

The barley lipid transfer protein (LTP1) adducted by an alpha-ketol, (9-hydroxy-10-oxo-12(Z)-octadecenoic acid) exhibits an unexpected high lipid transfer activity. The crystal structure of this oxylipin-adducted LTP1, (LTP1b) was determined at 1.8A resolution. The covalently bound oxylipin was partly exposed at the surface of the protein and partly buried within the hydrophobic cavity. The structure of the oxylipidated LTP1 emphasizes the unique plasticity of the hydrophobic cavity of these plant lipid-binding proteins when compared to the other members of the family. The plasticity of the hydrophobic cavity and increase of its surface hydrophobicity induced by the oxylipin account for the improvement of the lipid transfer activity of LTP1b. These observations open new perspectives to explore the different biological functions of LTPs, including their allergenic properties.

Screening of transfer DNA (tDNA) tagged lines of Arabidopsis thaliana for mutants defective in systemic acquired resistance led to the characterization of dir1-1 (defective in induced resistance [systemic acquired resistance, SAR]) mutant. It has been suggested that the protein encoded by the dir1 gene, i.e., DIR1, is involved in the long distance signaling associated with SAR. DIR1 displays the cysteine signature of lipid transfer proteins, suggesting that the systemic signal could be lipid molecules. However, previous studies have shown that this signature is not sufficient to define a lipid transfer protein, i.e., a protein capable of binding lipids. In this context, the lipid binding properties and the structure of a DIR1–lipid complex were both determined by fluorescence and X-ray diffraction. DIR1 is able to bind with high affinity two monoacylated phospholipids (dissociation constant in the nanomolar range), mainly lysophosphatidyl cholines, side-by-side in a large internal tunnel. Although DIR1 shares some structural and lipid binding properties with plant LTP2, it displays some specific features that define DIR1 as a new type of plant lipid transfer protein. The signaling function associated with DIR1 may be related to a specific lipid transport that needs to be characterized and to an additional mechanism of recognition by a putative receptor, as the structure displays on the surface the characteristic PxxP structural motif reminiscent of SH3 domain signaling pathways.

International audience; Lipid transfer proteins (LTP) and puroindolines are abundant lipid binding proteins of plant seeds. While LTP are ubiquitous plant proteins, puroindolines are only found in the seeds of plants from the Triticae and Avenae tribes. These proteins display a similar overall folding pattern but different lipid binding properties. The unique and diverse biological and technological functions of LTPs and puroindolines are closely related to their structural and lipid binding properties. These proteins are attractive to improve the agronomic performances and food quality of crops. Heterologous expression and genetic engineering should allow industrial production and enlarge applications of these lipid binding proteins.

cited By 37; International audience; Four trichothecene-producing strains of Fusarium graminearum were grown on three maize grain fractions, whole grain, degermed grain, and the germ, to determine the effect of natural substrates on mycotoxin production. Monitoring the ergosterol content after 25 days of incubation indicated that fungal growth on all grain fractions was comparable. Trichothecene (TCT) production was highest on degermed grain, less on whole grain, and very low or nondetectable on the germ; similar results were found with four different strains. It was concluded that inhibitor(s) of TCT biosynthesis were present in maize germ. The presence of phenolic compounds was investigated in the different fractions. The hydroxamate 4-acetylbenzoxazolin-2-one (4-ABOA), a known inhibitor of mycotoxin production, was found in the degermed and whole grain fractions but not in the germ. Therefore, the TCT inhibition observed on the maize germ fraction used in our study is clearly not linked to 4-ABOA. Other soluble phenolic compounds were found at a much higher concentration in the germ than in the two other fractions. The inhibition property of the soluble ester-bound extracts was tested in liquid culture. A possible role for these compounds is discussed.

Sixty F. culmorum strains were isolated from wheat grains collected from different wheat-growing areas in France and from different cultivars. The isolates were grown on autoclaved wheat grain to assess their ability to produce trichothecenes and zearalenone. Fungal biomass was evaluated through the ergosterol grain content. All the isolates produced zearalenone (0.39-1660 mg kg(-1)). Thirty-five of the 60 F. culmorum produced nivalenol (0.11-11.7 mg kg(-1)), 12 of 60 produced fusarenone X (0.05-8.42 mg kg(-1)), five of 60 produced 15-acetyldeoxynivalenol (0.48-27.7 mg kg(-1)), 13 of 60 produced 3-acetyldeoxynivalenol (0.07-21.0 mg kg(-1) and 24 of 60 produced deoxynivalenol (0.92-51.9 mg kg(-1)). According to the results, the distribution of the different chemotypes as well as the high and the low mycotoxin-producing Fusarium strains could not be associated to geographical origin.

The cuticle, an extracellular lipid matrix consisting of waxes and of a cutin skeleton is the outermost plants protection barrier against their environment. The cuticle is involved in many agronomic traits such as post-harvest storage, biomechanical or fruit appearance properties like surface brightness. In order to isolate cuticle mutants, the screening of an EMS tomato mutants collection has been undertaken, based on fruit brightness, leading to the selection of 24 mutants. Biochemical analyzes have shown wide variations in cuticle loads and compositions, especially in cutin mutants. The characterization of 4 remarkable mutants was undertaken to identify the mutations responsible for brightness phenotypes. The most affected mutant shows a cutin load reduced by 85% compared to the wild type, and is due to a mutation in the SlGDSL2 gene, encoding a GDSL-motive acylhydrolase enzyme, responsible for the cutin polymerization. In order to further study the cutin formation and regulation, the next work was to obtain and characterize single and double mutants affected in cutin monomer synthesis, apoplastic transport and cutin polymerization., La cuticule, une matrice lipidique extracellulaire constituée de cires et d’un squelette de cutine, est la barrière de défense la plus externe des plantes face à leur environnement. Elle intervient dans de nombreuses propriétés agronomiques comme la conservation post récolte, les propriétés mécaniques ou bien l’aspect du fruit, dont la brillance. Afin d’isoler des mutants de cuticule, le criblage d’une collection de mutants EMS de tomate a été entrepris, en se basant sur la brillance des fruits, conduisant à la sélection de 24 mutants. Chez ceux-ci, des analyses biochimiques ont montré de fortes variations de charge et de composition de la cuticule, notamment chez les mutants de cutine. La caractérisation de 4 mutants remarquables a été entreprise afin d’identifier les mutations responsables des phénotypes de brillance. Le mutant le plus affecté, présentant une charge en cutine réduite de 85% par rapport au type sauvage, a révélé une mutation du gène SlGDSL2 codant pour une acylhydrolase à motif GDSL, responsable de la polymérisation de la cutine. Afin d’étudier la formation et la régulation de la cutine, la suite du travail a consisté à obtenir et à caractériser des simples et des doubles mutants affectés dans la synthèse des monomères de cutine, le transport apoplastique et la polymérisation de la cutine.

Contact: pauline.ezanno@oniris-nantes.fr Diplôme : Dr. d'Université; Epidemiological models enable to better understand the dynamics of infectious diseases and to assess ex-ante control strategies. For Mycobacterium avium subsp. paratuberculosis (Map), possible transmission routes have been described, but Map spread in a herd and the relative importance of the routes are currently insufficiently understood to prioritize control measures. We aim to predict early after Map introduction in a dairy cattle herd whether infection is likely to fade out or persist, when no control measures are implemented, using a modelling approach. Both vertical transmission and horizontal transmission via the ingestion of colostrum, milk, or faeces present in the contaminated environment were modelled. Calf-to-calf indirect transmission was possible. Six health states were represented: susceptible, transiently infectious, latently infected, subclinically infected, clinically affected, and resistant. The model was partially validated by comparing the simulated prevalence with field data. Housing facilities and contacts between animals were specifically considered for calves and heifers. After the introduction of one infected animal in a naive herd, fadeout occurred in 66% of the runs. When Map persisted, the prevalence of infected animals increased to 88% in 25 years. The two main transmission routes were via the farm’s environment and in utero transmission. Calf-to-calf transmission was minor. Fadeout versus Map persistence could be differentiated with the number of clinically affected animals, which was rarely above one when fadeout occurred. Therefore, early detection of affected animals is crucial in preventing Map persistence in dairy herds

L'industrie du malt tente actuellement de réduire les coûts énergétiques (touraillage) sans affecter la qualité de malt obtenu. Cette économie d’énergie passe nécessairement par une diminution de la teneur en eau du grain d’orge en fin de trempe et durant la germination.Nous avons choisi d'étudier des paramètres clés de la qualité brassicole des malts concernant leurs capacités diastasiques et pro-mousse. Ainsi la diffusion et les modifications de la TP1, protéine pro-mousse du malt, ont montré des résultats équivalents pour un malt faiblement hydraté comparé à un malt fortement hydraté.Par contre, le taux d’hydratation du grain affecte la diffusion et l'activité des β-glucanases et en conséquence la dégradation des β-glucanes. Ces effets sont liés à une différence dans la cinétique de diffusion et de synthèse de ces enzymes et peuvent être fortement réduits en augmentant la durée de germination.La migration de l’eau dans le grain suit un cheminement particulier lié au contournement des barrières hydrophobes du grain situées en surface du péricarpe et à l’interface entre aleurone et péricarpe (testa). Sur des variétés produisant, au niveau pilote industriel, des malts qualitativement différents suivant le taux d’hydratation,nous avons remarqué de faibles différences de composition et d’épaisseur entre les assises cuticulaires. En revanche, nous avons mis en évidence une très grande variabilité de composition des cuticules dans les différentes parties du grain, par exemple le scutellum, le sillon ou les glumelles, During kilning, reduction of energy costs without impacting significantly the malt quality, represents a major challenge of the malting industry. This energy reduction requires a reduction of barley grain water content at the end of steeping and during germination.In the present work, we focused on key malting quality parameters involved in diastatic power and foam promoting capacities of malt. When analysed in a low hydrated malt and a high hydrated malt, the LTP1 (a foam promoting protein) modifications and its diffusion from the aleurone layer to the starchy endosperm were similar. The hydration level of the grain affects however β-glucanase diffusion and activity, and consequently the β-glucan degradation. These effects are linked to a delay in the synthesis and the diffusion of these enzymes.An increase of the time of germination allows to sharply reduce these effects.According to grain hydrophobic barriers localized at the pericarp surface and at the interface of aleurone and pericarp (testa), water diffusion inside the grain follows a specific pathway. Only weak, although significant,differences in cuticular thickness and composition were observed between cultivars with different malt qualities according to their hydration levels. On the contrary, we observed a great variability in the cuticular composition of the various tissues of the grain e.g. scutellum, chalaza or husk