Additive and Specific Effects of Elicitor Treatments on the Metabolic Profile of Arabidopsis thaliana

Several elicitors of plant defense have been identified and numerous efforts to use them in the field have been made. Exogenous elicitor treatments mimic the in planta activation of pattern-triggered immunity (PTI), which relies on the perception of pathogen-associated molecular patterns (PAMPs) such as bacterial flg22 or fungal chitins. Early transcriptional responses to distinct PAMPs are mostly overlapping, regardless of the elicitor being used. However, it remains poorly known if the same patterns are observed for metabolites and proteins produced later during PTI. In addition, little is known about the impact of a combination of elicitors on PTI and the level of induced resistance to pathogens. Here, we monitored Arabidopsis thaliana resistance to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 ( Pto DC3000) following application of flg22 and chitosan elicitors, used individually or in combination. A slight, but not statistically significant increase in induced resistance was observed when the elicitors were applied together when compared with individual treatments. We investigated the effect of these treatments on the metabolome by using an untargeted analysis. We found that the combination of flg22 and chitosan impacted a higher number of metabolites and deregulated specific metabolic pathways compared with the elicitors individually. These results contribute to a better understanding of plant responses to elicitors, which might help better rationalize their use in the field. Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International licens

O-glycosylation in plant and mammal cells: the use of chemical inhibitors to understand the biosynthesis and function of O-glycosylated proteins

Glycosylation is the most common posttranslational modification of proteins and consists of the addition of sugar moiety to proteins. The resulting glycosylated proteins are often secreted to the extracellular compartment or integrated into different cell organelles. This modification was identified in plant as well as in mammalian cells.  A number of plant and mammal proteins are either N- or O-glycosylated. This review focuses on O-glycosylation which refers to linkage of a glycan to hydroxyl group of serine, threonine or proline residues. O-glycosylation can be altered by the action of chemical inhibitors. For instance, 3,4-dehydro-L-proline, ethyl 3,4-dehydroxy benzoate and a,a-dipyridyl inhibit the activity of prolyl4-hydroxylase, a key enzyme for plant O-glycosylation. In addition, a small molecule inhibitor designated 1-68A inhibits the polypeptide N-acetylgalactosaminyltransferases of mammalian cells. The aim of this review is to summarize the role and mechanism of action of these inhibitors of O-glycosylation and their impact on cell development in plants and mammals

La thérapie par les plantes en Afrique : les polysaccharides de la paroi végétale

International audienceThis review article aims to draw attention to therapeutic potential of plant cell wall polysaccharides isolated from African medicinal plants. Plant cell wall, or plant cell extracellular compartment, consists on various polysaccharides having different chemical structures. Among these polysaccharides, cellulose, hemicelluloses and pectin polysaccharides are the predominant ones, and play an important role in controlling several biological processes like cell growth and morphogenesis, or defense mechanisms. The structure-function relationship of plant cell wall polysaccharides have been extensively studied, regarding their in vivo biological functions. Here, we have partially described the chemical structure of several biologically active hemicelluloses or pectin polysaccharides extracts, isolated from different African medicinal plants. It appears that these polysaccharides taken individually are able to modulate the activity of the mammal immune system in different manner, providing an interesting complementary therapy to immune deficient patients for instance. Further investigations on cell wall polysaccharide structure-biological activity relationship of the numerous unexplored medicinal plants are therefore strongly suggested.Dans cette revue, nous mettons en avant le potentiel thérapeutique des polysaccharides isolés à partir des parois végétales des plantes médicinales africaines. In vivo, la paroi végétale joue un rôle important dans le contrôle de la physiologie de la plante (croissance cellulaire, mécanismes de défense de la plante, morphologie de la plante). Principalement composée de polysaccharides comme la cellulose, les hémicelluloses ou de pectines, la relation entre la structure chimique de ces polysaccharides et leurs fonctions biologiques a fait l’objet de très nombreuses études. Des extraits de ces parois, principalement polysaccharidiques, isolés à partir de plantes sont également couramment utilisés comme « remède traditionnel» en Afrique. Dans cette revue, nous présentons quelques plantes médicinales africaines pour lesquelles la structure chimique de certains extraits polysaccharidiques, présentant souvent une activité immunomodulatoire, a été déterminée. Ce type d’étude et d’approche, encore marginale, gagnerait à être généralisé aux autres plantes médicinales africaines jusqu’alors peu étudiées. Cette propriété immunomodulatoire de certains extraits polysaccharidiques pourrait constituer un complément thérapeutique de choix chez des patients immunodéprimés ou immunodéficients

Plant Cell wall polysaccharides: immunomodulators of the immune system and source of natural fibers

International audienc

Constitutive expression of a grapevine polygalacturonase-inhibiting protein affects gene expression and cell wall properties in uninfected tobacco

Background Polygalacturonase-inhibiting proteins (PGIPs) directly limit the effective ingress of fungal pathogens by inhibiting cell wall-degrading endopolygalacturonases (ePGs). Transgenic tobacco plants over-expressing grapevine (Vitis vinifera) Vvpgip1 have previously been shown to be resistant to Botrytis infection. In this study we characterized two of these PGIP over-expressing lines with known resistance phenotypes by gene expression and hormone profiling in the absence of pathogen infection. Results Global gene expression was performed by a cross-species microarray approach using a potato cDNA microarray. The degree of potential cross-hybridization between probes was modeled by a novel computational workflow designed in-house. Probe annotations were updated by predicting probe-to-transcript hybridizations and combining information derived from other plant species. Comparing uninfected Vvpgip1-overexpressing lines to wild-type (WT), 318 probes showed significant change in expression. Functional groups of genes involved in metabolism and associated to the cell wall were identified and consequent cell wall analysis revealed increased lignin-levels in the transgenic lines, but no major differences in cell wall-derived polysaccharides. GO enrichment analysis also identified genes responsive to auxin, which was supported by elevated indole-acetic acid (IAA) levels in the transgenic lines. Finally, a down-regulation of xyloglucan endotransglycosylase/hydrolases (XTHs), which are important in cell wall remodeling, was linked to a decrease in total XTH activity. Conclusions This evaluation of PGIP over-expressing plants performed under pathogen-free conditions to exclude the classical PGIP-ePG inhibition interaction indicates additional roles for PGIPs beyond the inhibition of ePGs

Plant Cell wall polysaccharides: immunomodulators of the immune system and source of natural fibers

International audienc

Biocontrol of the parasitic plant species <em>Phelipanche ramosa</em>, using rapeseed rhizosphere fungi or phytotoxic metabolites they produce.

National audiencePhelipanche ramosa (L.) Pomel, branched broomrape, is a major root-holoparasitic damaging weed with a large host range besides a strong adaptation to rapeseed. Broomrape seed germination is necessarily triggered by host root exudates. This ensures that they germinate close to a host root where they attach and establish a vascular connection to take up water and nutrients. No efficient broomrape management technique has been validated yet. Biocontrol could be an alternative but there is currently no biological control agent on the market. Indeed tripartite interactions between the host plant, the parasitic plant and a pathogenic agent of the latter are complex and poorly understood. The objective here is to meet this challenge and identify biocontrol products of P. ramosa. These products may be fungal strains or fungal secondary metabolites phytotoxic for broomrape seeds and stems. A molecular approach will characterize the diversity of endophytic fungal communities of healthy and symptomatic broomrape stems. In addition, a microbiological approach will isolate fungi associated with broomrape lethal symptoms. They will be tested for their phytotoxic activity through pathogenicity tests, metabolomic analyses of plant-fungus interactions and cytological analyses. Fungal strains specifically pathogenic on broomrape will be provided to control the subterranean development of the parasitic plant and phytotoxic metabolites could constitute an innovative mycoherbicide to develop

The role of AGP’s in root-microbe interactions. Plant-pathogen interactions from the perspective of the plant cell wall: new approaches to improve crop protection against fungal pathogens

International audienc

Immunité végétale : le rôle de la coiffe racinaire et ses sécrétions dans la protection des plantes

International audienc

Arabinogalactan proteins in root–microbe interactions

International audienc