Métodos y técnicas de monitoreo y predicción temprana en los escenarios de riesgos socionaturales

Esta obra concentra los métodos y las técnicas fundamentales para el seguimiento y monitoreo de las dinámicas de los escenarios de riesgos socionaturales (geológicos e hidrometeorológicos) y tiene como objetivo general orientar, apoyar y acompañar a los directivos y operativos de protección civil en aterrizar las acciones y políticas públicas enfocadas a la gestión del riesgo local de desastre

Dégradation enzymatique des parois du grain de blé (Triticum aestivum) par une endoxylanase de Trichoderma viride (Application à l'étude de la structure des arabinoxylanes et de leur variabilité)

La dégradation enzymatique des parois du grain de blé (Triticum aestivum) et son application à l'étude de la variabilité structurale des arabinoxylanes (AX) de l'albumen amylacé a été entreprise pour mieux comprendre les propriétés des parois et maîtriser les mécanismes de biosynthèse qui les modulent. Les produits de dégradation des AX par une endoxylanase de Trichoderma viride ont été isolés et caractérisés par RMN du proton, puis utilisés pour produire des anticorps monoclonaux dirigés contre les AX. Les règles de leur fragmentation en spectrométrie de masse (ESI-Q-TOF) ont été établies. La xylanase a ensuite permis d'étudier la variabilité structurale des AX, et les relations entre AX solubles et insolubles ont été établies. Une méthode d'analyse rapide, basée sur l'empreinte enzymatique des AX, a été développée. Elle permet de discriminer les variétés et d'envisager leur criblage pour la recherche de QTL liés à la structure des AX et aux gènes de biosynthèse de ces macromolécules.The enzymatic degradation of wheat (Triticum aestivum) grain cell walls and its application to study the structural variability of arabinoxylans (AX) from endosperm was carried out in order to better understand the properties of the walls and to control the mechanisms of biosynthesis which modulate them. AX degradation products by an endoxylanase from Trichoderma viride were isolated and characterized by proton NMR. Isolated oligomers were used to produce monoclonal antibodies directed against AX. Their fragmentation rules in mass spectrometry (ESI-Q-TOF) were also established. The xylanase was then used to study the variability of AX and structural relationship between the soluble and insoluble fractions of AX were established. A new fast method, based on the enzymatic fingerprinting of AX, was developed and allowed to discriminate wheat cultivars. This method allowed to screen cultivars to find QTL related to AX structure and thus to highlight genes involved in their biosynthesis.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Structural characterization of underivatized arabino-xylo-oligosaccharides by negative-ion electrospray mass spectrometry

International audienceVarious arabino-xylo-oligosaccharides with known substitution patterns were assessed by negative ESI-Q-TOFMS and ESI-ITMS. The CID spectra of linear xylo-oligosaccharides and of nine isomeric mono- and disubstituted arabino-xylo-oligosaccharides established that structures differing in their substitution pattern can be differentiated by this approach. The negative-ion fragmentation spectra of the deprotonated quasi-molecular ions are mainly characterized by glycosidic cleavage ions from the C-series, which provide sequence informations, and by cross-ring cleavage 0,2Ai ions, which provide partial linkage information. When the collision energy increased, the cross-ring cleavage 0,2Ai ions underwent consecutive loss of water to produce 0,2Ai − 18 fragment ions and glycosidic cleavage ions of the B-series are also produced besides the Ci ions. Contrary to linear xylo-oligosaccharides, Ci ions, which originate from C-3 monosubstituted xylosyl residues never produce the related cross-ring cleavage 0,2Ai ions. Disubstitution at O-2 and O-3 of xylosyl residues appears to enhance the production of the 0,2Ai ions compared to monosubstitution. For the differentiation of the mono- and disubstitution patterns of the penultimate xylosyl residue, the relative abundance of the glycosidic cleavage ions at m/z 263 and 299 found on Q-TOF CID spectra plays a relevant role and appears to be more informative than MSn spectra obtained on a ion trap instrument

Classification of wheat varieties based on structural features of arabinoxylans as revealed by endoxylanase treatment of flour and grain

International audienc

Developing pericarp of maize: a model to study arabinoxylan synthesis and feruloylation

Cell walls are comprised of networks of entangled polymers that differ considerably between species, tissues and developmental stages. The cell walls of grasses, a family that encompasses major crops, contain specific polysaccharide structures such as xylans substituted with feruloylated arabinose residues. Ferulic acid is involved in the grass cell wall assembly by mediating linkages between xylan chains and between xylans and lignins. Ferulic acid contributes to the physical properties of cell walls, it is a hindrance to cell wall degradability (thus biomass conversion and silage digestibility) and may contribute to pest resistance. Many steps leading to the formation of grass xylans and their cross-linkages remain elusive. One explanation might originate from the fact that many studies were performed on lignified stem tissues. Pathways leading to lignins and feruloylated xylans share several steps, and lignin may impede the release and thus the quantification of ferulic acid. To overcome these difficulties, we used the pericarp of the maize B73 line as a model to study feruloylated xylan synthesis and crosslinking. Using Fourier-transform infra-red spectroscopy and biochemical analyses, we show that this tissue has a low lignin content and is composed of approximately 50% heteroxylans and approximately 5% ferulic acid. Our study shows that, to date, maize pericarp contains the highest level of ferulic acid reported in plant tissue. The detection of feruloylated xylans with a polyclonal antibody shows that the occurrence of these polysaccharides is developmentally regulated in maize grain. We used the genomic tools publicly available for the B73 line to study the expression of genes within families involved or suggested to be involved in the phenylpropanoid pathway, xylan formation, feruloylation and their oxidative crosslinking. Our analysis supports the hypothesis that the feruloylated moiety of xylans originated from feruloylCoA and is transferred by a member of the BAHD acyltransferase family. We propose candidate genes for functional characterization that could subsequently be targeted for grass crop breeding

Placenta, Pericarp, and Seeds of Tabasco Chili Pepper Fruits Show a Contrasting Diversity of Bioactive Metabolites

Chili pepper (Capsicum spp.) is one of the most important horticultural crops worldwide, and its unique organoleptic properties and health benefits have been established for centuries. However, there is little knowledge about how metabolites are distributed throughout fruit parts. This work focuses on the use of liquid chromatography coupled with high resolution mass spectrometry (UHPLC-ESI-HRMS) to estimate the global metabolite profiles of the pericarp, placenta, and seeds of Tabasco pepper fruits (Capsicum frutescens L.) at the red mature stage of ripening. Our main results putatively identified 60 differential compounds between these tissues and seeds. Firstly, we found that pericarp has a higher content of glycosides, showing on average a fold change of 5 and a fold change of 14 for terpenoids when compared with other parts of the fruit. While placenta was the richest tissue in capsaicinoid-related compounds, alkaloids, and tocopherols, with a 35, 3, and 7 fold change, respectively. However, the seeds were richer in fatty acids and saponins with fold changes of 86 and 224, respectively. Therefore, our study demonstrates that a non-targeted metabolomic approach may help to improve our understanding of unexplored areas of plant metabolism and also may be the starting point for a detailed analysis in complex plant parts, such as fruits

Le péricarpe du grain de maïs : un modèle pour étudier la synthèse et la féruloylation des arabinoxylanes

National audienc

Metabolomic Markers for the Early Selection of Coffea canephora Plants with Desirable Cup Quality Traits

Genetic improvement of coffee plants represents a great challenge for breeders. Conventional breeding takes a too long time for responding timely to market demands, climatic variations and new biological threads. The correlation of genetic markers with the plant phenotype and final product quality is usually poor. Additionally, the creation and use of genetically modified organisms (GMOs) are often legally restricted and rejected by customers that demand natural products. Therefore, we developed a non-targeted metabolomics approach to accelerate conventional breeding. Our main idea was to identify highly heritable metabolites in Coffea canephora seedlings, which are linked to coffee cup quality. We employed a maternal half-sibs approach to estimate the metabolites heritability in open-pollinated plants in both leaves and fruits at an early plant development stage. We evaluated the cup quality of roasted beans and correlated highly heritable metabolites with sensory quality traits of the coffee beverage. Our results provide new insights about the heritability of metabolites of C. canephora plants. Furthermore, we found strong correlations between highly heritable metabolites and sensory traits of coffee beverage. We revealed metabolites that serve as predictive metabolite markers at an early development stage of coffee plants. Informed decisions can be made on plants of six months old, compared to 3.5 to 5 years using conventional selection methods. The metabolome-wide association study (MWAS) drastically accelerates the selection of C. canephora plants with desirable characteristics and represents a novel approach for the focused breeding of crops

Genomic history of the origin and domestication of common bean unveils its closest sister species.

BackgroundModern civilization depends on only a few plant species for its nourishment. These crops were derived via several thousands of years of human selection that transformed wild ancestors into high-yielding domesticated descendants. Among cultivated plants, common bean (Phaseolus vulgaris L.) is the most important grain legume. Yet, our understanding of the origins and concurrent shaping of the genome of this crop plant is limited.ResultsWe sequenced the genomes of 29 accessions representing 12 Phaseolus species. Single nucleotide polymorphism-based phylogenomic analyses, using both the nuclear and chloroplast genomes, allowed us to detect a speciation event, a finding further supported by metabolite profiling. In addition, we identified ~1200 protein coding genes (PCGs) and ~100 long non-coding RNAs with domestication-associated haplotypes. Finally, we describe asymmetric introgression events occurring among common bean subpopulations in Mesoamerica and across hemispheres.ConclusionsWe uncover an unpredicted speciation event in the tropical Andes that gave rise to a sibling species, formerly considered the "wild ancestor" of P. vulgaris, which diverged before the split of the Mesoamerican and Andean P. vulgaris gene pools. Further, we identify haplotypes strongly associated with genes underlying the emergence of domestication traits. Our findings also reveal the capacity of a predominantly autogamous plant to outcross and fix loci from different populations, even from distant species, which led to the acquisition by domesticated beans of adaptive traits from wild relatives. The occurrence of such adaptive introgressions should be exploited to accelerate breeding programs in the near future