Dual Transcriptomic and Metabolomic Analysis of Elicited Flax Sheds Light on the Kinetics of Immune Defense Activation Against the Biotrophic Pathogen .

Flax () grown under controlled conditions displayed genotype-dependent resistance to powdery mildew () following COS-OGA (comprising chitosan- and pectin-derived oligomers) elicitor application. The present study reveals a two-step immune response in plants preventively challenged with the elicitor: an initial, rapid response characterized by the transcription of defense genes whose protein products act in contact with or within the cell wall, where biotrophic pathogens initially thrive, followed by a prolonged activation of cell wall peroxidases and accumulation of secondary metabolites. Thus, dozens of genes encoding membrane receptors, pathogenesis-related proteins, and wall peroxidases were initially overexpressed.

Modulation of plant plasma membrane structure by exogenous fatty acid hydroperoxide is a potential perception mechanism for their eliciting activity.

Oxylipins are lipid-derived molecules that are ubiquitous in eukaryotes and whose functions in plant physiology have been widely reported. They appear to play a major role in plant immunity by orchestrating reactive oxygen species (ROS) and hormone-dependent signalling pathways. The present work focuses on the specific case of fatty acid hydroperoxides (HPOs).

Chloroplast Electron Chain, ROS Production, and Redox Homeostasis Are Modulated by COS-OGA Elicitation in Tomato () Leaves.

The stimulation of plant innate immunity by elicitors is an emerging technique in agriculture that contributes more and more to residue-free crop protection. Here, we used RNA-sequencing to study gene transcription in tomato leaves treated three times with the chitooligosaccharides-oligogalacturonides (COS-OGA) elicitor FytoSave that induces plants to fend off against biotrophic pathogens. Results showed a clear upregulation of sequences that code for chloroplast proteins of the electron transport chain, especially Photosystem I (PSI) and ferredoxin.

Systemic defense activation by COS-OGA in rice against root-knot nematodes depends on stimulation of the phenylpropanoid pathway.

Activation of induced plant resistance to control pests and diseases is regaining attention in the current climate where chemical pesticides are being progressively banned. Formulations of chitosan oligomers (COS) and pectin-derived oligogalacturonides (OGA), COS-OGA, have previously been described to induce resistance against fungal diseases in different crop plants. Here, we investigated their potential and mode-of-action as preventive measures to control root-knot nematode Meloidogyne graminicola infection in rice.

Plant immunity induced by COS-OGA elicitor is a cumulative process that involves salicylic acid.

Plant innate immunity offers considerable opportunities for plant protection but beside flagellin and chitin, not many molecules and their receptors have been extensively characterized and very few have successfully reached the field. COS-OGA, an elicitor that combines cationic chitosan oligomers (COS) with anionic pectin oligomers (OGA), efficiently protected tomato (Solanum lycopersicum) grown in greenhouse against powdery mildew (Leveillula taurica). Leaf proteomic analysis of plants sprayed with COS-OGA showed accumulation of Pathogenesis-Related proteins (PR), especially subtilisin-like proteases.

Identification of a cytotoxic molecule in heat-modified citrus pectin.

Modified forms of citrus pectin possess anticancer properties. However, their mechanism of action and the structural features involved remain unclear. Here, we showed that citrus pectin modified by heat treatment displayed cytotoxic effects in cancer cells.

Loss of function of 1-FEH IIb has more impact on post-harvest inulin degradation in Cichorium intybus than copy number variation of its close paralog 1-FEH IIa.

Key Message: The loss of mini-exon 2 in the 1-FEH IIb glycosyl-hydrolase results in a putative non-functional allele. This loss of function has a strong impact on the susceptibility to post-harvest inulin depolymerization. Significant variation of copy number was identified in its close paralog 1-FEH IIa, but no quantitative effect of copy number on carbohydrates-related phenotypes was detected.

Heat-modified citrus pectin induces apoptosis-like cell death and autophagy in HepG2 and A549 cancer cells.

Cancer is still one of the leading causes of death worldwide, and finding new treatments remains a major challenge. Previous studies showed that modified forms of pectin, a complex polysaccharide present in the primary plant cell wall, possess anticancer properties. Nevertheless, the mechanism of action of modified pectin and the pathways involved are unclear.

Tracking developmentally regulated post-synthetic processing of homogalacturonan and chitin using reciprocal oligosaccharide probes.

Polysaccharides are major components of extracellular matrices and are often extensively modified post-synthetically to suit local requirements and developmental programmes. However, our current understanding of the spatiotemporal dynamics and functional significance of these modifications is limited by a lack of suitable molecular tools. Here, we report the development of a novel non-immunological approach for producing highly selective reciprocal oligosaccharide-based probes for chitosan (the product of chitin deacetylation) and for demethylesterified homogalacturonan.

Development and characterization of microsatellite loci for the Moroccan endemic endangered species Argania spinosa (Sapotaceae).

Premise Of The Study: Microsatellite loci were developed for the Moroccan endemic endangered species Argania spinosa with a combination of a typical library enrichment procedure and a 454 GS FLX Titanium-based high-throughput sequencing approach. •

Methods And Results: A genomic DNA library was enriched and further screened using (GA)15, (GTA)8, and (TTC)8 biotin-labeled probes coupled with chemi-luminescence detection. To increase simple sequence repeat (SSR) loci number, an ultra-high-throughput sequencing-based approach was used.

Specific localization and measurement of hydrogen peroxide in Arabidopsis thaliana cell suspensions and protoplasts elicited by COS-OGA.

H2O2 acts as an important signaling molecule during plant/pathogen interactions but its study remains a challenge due to the current shortcomings in H2O2-responsive probes. In this work, ContPY1, a new molecular probe developed to specifically detect H2O2 was used to study the elicitation of Arabidopsis thaliana cells by a complex of chitosan oligomers (COS) and oligogalacturonides (OGA). The comparison of cell suspensions, protoplasts of cell suspensions and leaf protoplasts treated with different inhibitors gave indications on the potential sources of hydrogen peroxide in plant cells.

Validation of the boronate sensor ContPY1 as a specific probe for fluorescent detection of hydrogen peroxide in plants.

Studying the implication of hydrogen peroxide in biological processes in plants remains a challenge due to the current shortcomings of H2O2-responsive probes. The use of ContPY1, a new fluorescent probe, which is highly selective and sensitive for H2O2, was investigated. To validate the use of ContPY1 on plants, we have generated protocols employing cells suspensions and leaves, and measured specifically H2O2 production by plants using spectrofluorometry and microscopy.

Mutations in chicory FEH genes are statistically associated with enhanced resistance to post-harvest inulin depolymerization.

Nucleotidic polymorphisms were identified in fructan exohydrolases genes which are statistically associated with enhanced susceptibility to post-harvest inulin depolymerization. Industrial chicory (Cichorium intybus L.) root is the main commercial source of inulin, a linear fructose polymer used as dietary fiber.

Anti-cancer activities of pH- or heat-modified pectin.

Despite enormous efforts that have been made in the search for novel drugs and treatments, cancer continues to be a major public health problem. Moreover, the emergence of resistance to cancer chemotherapy often prevents complete remission. Researchers have thus turned to natural products mainly from plant origin to circumvent resistance.

Brucella melitensis 16M produces a mannan and other extracellular matrix components typical of a biofilm.

Mutations in the Brucella melitensis quorum-sensing (QS) system are involved in the formation of clumps containing an exopolysaccharide. Here, we show that the overexpression of a gene called aiiD in B. melitensis gives rise to a similar clumping phenotype.

Chitosan oligosaccharides modulate the supramolecular conformation and the biological activity of oligogalacturonides in Arabidopsis.

Plant cell walls undergo remodeling during growth and development and are the first target of many invading pathogens. Acidic pectin (homogalacturonans) binds calcium and forms chain dimers called egg boxes and even multimers at higher calcium ion concentrations. Chitosan, the deacetylated form of chitin produced by fungi when invading plant tissues, is a cationic polymer that can interact with negatively charged pectin.

Insight into cellular response of plant cells confined within silica-based matrices.

The encapsulation of living plant cells into materials could offer the possibility to develop new green biochemical technologies. With the view to designing new functional materials, the physiological activity and cellular response of entrapped cells within different silica-based matrices have been assessed. A fine-tuning of the surface chemistry of the matrix has been achieved by the in situ copolymerization of an aqueous silica precursor and a biocompatible trifunctional silane bearing covalently bound neutral sugars.

Construction of 12 EST libraries and characterization of a 12,226 EST dataset for chicory (Cichorium intybus) root, leaves and nodules in the context of carbohydrate metabolism investigation.

Background: The industrial chicory, Cichorium intybus, is a member of the Asteraceae family that accumulates fructan of the inulin type in its root. Inulin is a low calories sweetener, a texture agent and a health promoting ingredient due to its prebiotic properties. Average inulin chain length is a critical parameter that is genotype and temperature dependent.

Characterisation of two cold induced dehydrin genes from Cichorium intybus L.

Two dehydrin genes were identified from a Cichorium intybus EST database. They were among the most abundant sequences obtained from 10 cDNA libraries constructed from chicory roots grown under field conditions. The full length cDNA sequences, designated CiDHN1 and CiDHN2, were 1,176 and 1,055 bp long and encoded predicted polypeptides of 262 and 261 amino acids, respectively.

Egg box conformation of oligogalacturonides: the time-dependent stabilization of the elicitor-active conformation increases its biological activity.

Circular dichroism spectrometry was used on oligogalacturonides (OGAs) and showed the existence of a calcium/sodium-induced conformational state that is intermediate between single-isolated chains and calcium-associated multimer chains. This conformation is interpreted as being egg box dimers. Using the 2F4 monoclonal antibody that specifically binds such an egg box dimer conformation of pectin, the stability of OGA dimers was investigated over a period of 24 hours.

Pectin methylesterases induce an abrupt increase of acidic pectin during strawberry fruit ripening.

The decrease of strawberry (Fragariaxananassa Duch.) fruit firmness observed during ripening is partly attributed to pectolytic enzymes: polygalacturonases, pectate lyases and pectin methylesterases (PMEs). In this study, PME activity and pectin content and esterification degree were measured in cell walls from ripening fruits.

In vitro characterization of the homogalacturonan-binding domain of the wall-associated kinase WAK1 using site-directed mutagenesis.

Wall-associated kinase 1--WAK1 is a transmembrane protein containing a cytoplasmic Ser/Thr kinase domain and an extracellular domain in contact with the pectin fraction of the plant cell wall in Arabidopsis thaliana (L.) HEYNH. In a previous paper [Decreux, A.

Polymorphism and modulation of cell wall esterase enzyme activities in the chicory root during the growing season.

Pectins are major components of the primary plant cell wall. They can be both methylesterified and acetylesterified and de-esterification occurs by specific esterases. Proteins extracted by NaCl treatment from root cell walls of two chicory varieties (Cichorium intybus L.

Production and characterization of a phage-display recombinant antibody against carrageenans: evidence for the recognition of a secondary structure of carrageenan chains present in red algae tissues.

We report the isolation, for the first time by phage display, of a scFv recombinant antibody called B3 directed against carrageenans, the major sulphated polysaccharides of red seaweeds. Immunoassays were used to characterize the binding of B3 antibodies toward the three main carrageenan forms (iota, kappa, and lambda) differing by their sulfonic ester content and the presence of 3,6-anhydrogalactose. In enzyme-linked immunoadsorbent assay (ELISA), B3 soluble scFv showed a high reactivity towards iota-carrageenan at any titer but, at high titer only, recognized also the highly sulfated lambda-form.