Potentialisation de l’efficacité d’un stimulateur de défense par un biostimulant contre le mildiou de la vigne

L’induction de résistance des cultures aux maladies par des Stimulateurs de Défenses desPlantes (SDP) est l’une des stratégies envisagées pour réduire l'utilisation des pesticides de synthèse.Cependant, la variabilité de son efficacité au champ freine son développement. L’une des raisons estque, contrairement aux fongicides qui agissent directement sur les agents pathogènes, les SDP sollicitentl'immunité de la plante, dont la performance peut dépendre de son état physiologique. Outre les SDP,d'autres produits utilisés en agriculture, les biostimulants (BS), sont décrits pour améliorer certainesfonctions de la plante. Dans ce contexte, l'objectif de ce travail était de vérifier sur vigne si …

Seeking an apoplastic stomatal dysregulation factor - Bioassay guided fractionation and proteomic analysis of apoplastic fluids from Vitis vinifera leaves infected by Plasmopara viticola

Identification and characterization of the grapevine flagellin receptor vvfls2

International audience

Carbohydrates in plant immunity and plant protection: roles and potential application as foliar sprays.

International audience; Increasing interest is devoted to carbohydrates for their roles in plant immunity. Some of them are elicitors of plant defenses whereas other ones act as signaling molecules in a manner similar to phytohormones. This review first describes the main classes of carbohydrates associated to plant immunity, their role and mode of action. More precisely, the state of the art about perception of "PAMP, MAMP, and DAMP (Pathogen-, Microbe-, Damage-Associated Molecular Patterns) type" oligosaccharides is presented and examples of induced defense events are provided. A particular attention is paid to the structure/activity relationships of these compounds. The role of sugars as…

Characterization of the role of flagellin in the innate immunity triggered by the endophytic pgpr burkholderia phytofirmans in arabidopsis and grapevine

International audience

USE OF ALGINATES OLIGOMERS TO IMPROVE PLANT PROTECTION AGAINST PATHOGENS

The invention concerns the use of alginate oligomers in sequence α(1-4)Guluronane and/or ß(1-4)Mannuronane having a DP greater than 30, as an active ingredient of biocontrol products in plants, and that may be combined with another molecules such as phytohormones, against cryptogamic diseases of plants, in particular of vine (Vitis vinifera), or to protect other species against aggressors such as pathogenic microbes or insects.

Stomatal deregulation in Plasmopara viticola-infected grapevine leaves.

International audience; In grapevine, the penetration and sporulation of Plasmopara viticola occur via stomata, suggesting functional relationships between guard cells and the pathogen. This assumption was supported by our first observation that grapevine (Vitis vinifera cv. Marselan) cuttings infected by P. viticola wilted more rapidly than healthy ones when submitted to water starvation. • Here, complementary approaches measuring stomatal conductance and infrared thermographic and microscopic observations were used to investigate stomatal opening/closure in response to infection. • In infected leaves, stomata remained open in darkness and during water stress, leading to increased transpir…

Activation of Grapevine Defense Mechanisms: Theoretical and Applied Approaches

part 4.; International audience; Grapevine, as other plants, possesses an innate immune system that usually prevents infection by pathogens. General elicitors are compounds of different biochemical families capable of inducing plant defense reactions. In grapevine, the cascade of defense events induced by elicitors has been studied among others in cell suspensions. The perception of the elicitor triggers signaling events that allow the activation of defense genes encoding PR proteins and other proteins involved in phytoalexin production and cell wall reinforcement. The grapevine phytoalexins resveratrol and derivated compounds have been largely studied. In addition to their antimicrobial ac…

Changes in carbohydrate metabolism in Plasmopara viticola-infected grapevine leaves.

International audience; The oomycete Plasmopara viticola is responsible for downy mildew, a severe grapevine disease. In infected grapevine leaves, we have observed an abnormal starch accumulation at the end of the dark period, suggesting modifications in starch metabolism. Therefore, several complementary approaches, including transcriptomic analyses, measurements of enzyme activities, and sugar quantification, were performed in order to investigate and to understand the effects of P. viticola infection on leaf starch and-to a larger extent-carbohydrate metabolism. Our results indicate that starch accumulation is associated with an increase in ADP-glucose pyrophosphorylase (AGPase) activit…

Lutter contre les infections bactériennes : le système immunitaire des plantes est aussi très efficace !

SPE IPM UB CNRS Agrosup

How Plasmopara viticola is able to alter grapevine leaf physiology

National audience

Induced resistance as a strategy for vineyard protection

National audience; As most grown grapevine Vitis vinifera varieties are susceptible to diseases such as downy and powdery mildews, numerous treatments are required to ensure a satisfactory yield and harvest quality. However, the use of phytochemical fungicides has serious drawbacks: some of them are potentially harmful for the environment and human health and contribute to the selection of resistant pathogen strains. Nowadays, in an objective of sustainable viticulture, there is increasing societal request, political incitation and winegrower’s awareness to reduce the use of pesticides. For these reasons, alternative strategies of protection are under research. In our laboratory, we are stu…

Trehalose and trehalose-6-phosphate induce stomatal movements and interfere with ABA-induced stomatal closure in grapevine

Aims: The effects of trehalose and trehalose-6-phosphate (T6P), among other sugars, were assessed on grapevine stomatal movements. Methods and results: Epidermal peels were used to assess the effects of sugars. Low concentrations of trehalose and T6P (1 μM) induced an osmotic-independent reduction of the stomatal aperture in light conditions. Furthermore, ABA-induced stomatal closure was reduced by sugar application in association with lower accumulation of reactive oxygen species in guard cells. Similar effects, although weaker, were observed in response to the disaccharides sucrose and maltose, but not in response to the monosaccharides fructose and glucose. Conclusion: This study clearly…

Biovi : a research program for reducing chemical input in vine and wine

Decrease of chemical inputs during vine management and winemaking is of great importance from a political and societal point of view. In our ongoing project we propose alternative tools to chemicals in the vineyard and the cellar. We have compared a conventional vineyard protection strategy to an alternative strategy using copper and biocontrol products (Biocontrol) against downy and powdery mildews. Both strategies were compared regarding sanitary quality, berries and/or must enological parameters, and physical, biochemical and biological characteristics (berry surface observation, proteomic, metabolomic, volatilomic, metagenomic analyses). Musts obtained with both strategies were then use…

Toward the Identification of Two Glycoproteins Involved in the Stomatal Deregulation of Downy Mildew–Infected Grapevine Leaves

SPE Pôle IPM UB; International audience; Stomata remain abnormally opened and unresponsive to abscisic acid in grapevine leaves infected by downy mildew. This deregulation occurs from 3 days post inoculation and increases concomitantly with leaf colonization by the pathogen. Using epidermal peels, we demonstrated that the active compound involved in this deregulation is located in the apoplast. Biochemical assays showed that the active compound present in the apoplastic fluids isolated from Plasmopara viticola infected grapevine leaves (IAF) is a CysCys bridge-independent, thermostable and glycosylated protein. Fractionation guided assays based on chromatography / stomatal response and prot…

Bestim network : stimulating plant health in agroécological systems

The evolution of agriculture is facing strong societal expectations. One of them is to drasticallyreduce the use of synthetic inputs and in particular of plant protection products (PPP). In response,farmers and professionals in charge of agricultural development must invent a so-called "agroecological" agriculture, by ensuring profitability and sustainability of production systems and byimplementing a combination of many levers. The BESTIM network is part of this logic and proposes theconcept of "agroecological immunity" which aims to optimize the stimulation of plant health in efficientagroecological systems. We’ve adapted the concept of ecological immunity initially described in theanimal…

The grapevine flagellin receptor VvFLS2 differentially recognizes flagellin-derived epitopes from the endophytic growth-promoting bacterium Burkholderia phytofirmans and plant pathogenic bacteria.

International audience; The role of flagellin perception in the context of plant beneficial bacteria still remains unclear. Here, we characterized the flagellin sensing system flg22-FLAGELLIN SENSING 2 (FLS2) in grapevine, and analyzed the flagellin perception in the interaction with the endophytic plant growth-promoting rhizobacterium (PGPR) Burkholderia phytofirmans. The functionality of the grapevine FLS2 receptor, VvFLS2, was demonstrated by complementation assays in the Arabidopsis thaliana fls2 mutant, which restored flg22-induced H2O2 production and growth inhibition. Using synthetic flg22 peptides from different bacterial origins, we compared recognition specificities between VvFLS2…

Image analysis methods for assessment of H2O2 production and Plasmopara viticola development in grapevine leaves: application to the evaluation of resistance to downy mildew.

article i nfo The grapevine downy mildew (Plasmopara viticola) provokes severe damages and destroys the harvest in the absence of an effective protection. Numerous fungicide treatments are thus generally necessary. To promote a sustainable production, alternative strategies of protection including new antifungal molecules, resistant geno- types or elicitor-induced resistance are under trial. To evaluate the relevance of these strategies, resistance tests are required. In this context, three image analysis methods were developed to read the results of tests performed to assessP.viticolasporulation and mycelial development, and H 2 O 2 production in leaves. They have been validated using elic…

Dual mode of action of grape cane extracts against Botrytis cinerea

International audience; Crude extracts of Vitis vinifera canes represent a natural source of stilbene compounds with well characterized antifungals properties. In our trials, exogenous application of a stilbene extract (SE) obtained from grape canes on grapevine leaves reduces the necrotic lesions caused by Botrytis cinerea. The SE showed to possess a direct antifungal activity by inhibiting the mycelium growth. The activation of some grapevine defense mechanism was also investigated. H2O2 production and activation of mitogen-activated protein kinase (MAPK) phosphorylation cascades as well as accumulation of stilbenoid phytoalexins were explored on grapevine cell suspension. Moreover, the t…

Are grapevine stomata involved in the elicitor-induced protection against downy mildew?

Stomata, natural pores bordered by guard cells, regulate transpiration and gas exchanges between plant leaves and the atmosphere. These natural openings also constitute a way of penetration for microorganisms. In plants, the perception of potentially pathogenic microorganisms or elicitors of defense reactions induces a cascade of events, including H2O2 production, that allows the activation of defense genes, leading to defense reactions. Similar signaling events occur in guard cells in response to the perception of abscisic acid (ABA), leading to stomatal closure. Moreover, few elicitors were reported to induce stomatal closure in Arabidopsis and Vicia faba leaves. Because responses to ABA…

Development of a chitosan-based biocontrol product against crop diseases

Induced resistance as a strategy for vineyard protection

National audience

Analysis of the Molecular Dialogue Between Gray Mold (Botrytis cinerea) and Grapevine (Vitis vinifera) Reveals a Clear Shift in Defense Mechanisms During Berry Ripening

Mature grapevine berries at the harvesting stage (MB) are very susceptible to the gray mold fungus Botrytis cinerea, while veraison berries (VB) are not. We conducted simultaneous microscopic and transcriptomic analyses of the pathogen and the host to investigate the infection process developed by B. cinerea on MB versus VB, and the plant defense mechanisms deployed to stop the fungus spreading. On the pathogen side, our genome-wide transcriptomic data revealed that B. cinerea genes upregulated during infection of MB are enriched in functional categories related to necrotrophy, such as degradation of the plant cell wall, proteolysis, membrane transport, reactive oxygen species (ROS) genera…

In situ Phenotyping of Grapevine Root System Architecture by 2D or 3D Imaging: Advantages and Limits of Three Cultivation Methods

International audience; The root system plays an essential role in the development and physiology of the plant, as well as in its response to various stresses. However, it is often insufficiently studied, mainly because it is difficult to visualize. For grapevine, a plant of major economic interest, there is a growing need to study the root system, in particular to assess its resistance to biotic and abiotic stresses, understand the decline that may affect it, and identify new ecofriendly production systems. In this context, we have evaluated and compared three distinct growing methods (hydroponics, plane, and cylindric rhizotrons) in order to describe relevant architectural root traits of …