Role of Lys-M Receptor Kinases in the perception of chitooligosaccharides to trigger signaling events and immune responses in grapevine (Vitis vinifera)

International audienceThe establishment of defense reactions to protectplants against invading pathogens first requires therecognition of Microbe-Associated MolecularPatterns (MAMPs), detected by plasma membrane-bound Pattern Recognition Receptors (PRRs). TheseMAMPs, also termed elicitors, are used in severalbiocontrol products that are gradually developing toreduce the use of chemical pesticides inagriculture. Chitin, the main component of fungalcell walls, as well as its deacetylated derivative,chitosan, are two chitooligosaccharides (COS) thatcan be found in some of these products.Unfortunately, the mechanism allowing theperception of these molecules is still poorlyunderstood in Vitis vinifera, sometimes hamperingthe improvement and the generalization of theseemerging crop protection tools. On the contrary,chitin perception in the model plant Arabidopsisthaliana is well described and relies on a tripartitecomplex formed by three membrane-bound LysMReceptor-Like Kinases named AtLYK1/CERK1, AtLYK4& AtLYK5, the latter having the strongest affinity tochitin. In grapevine, we have demonstrated that COSperception rely on VvLYK1-1 & VvLYK1-2 but not onVvLYK1-3. In this context, we recently performedexperiments to complement the Arabidopsis lyk5simple mutant and the lyk4/5 double mutant, whichshowed altered response to COS, by overexpressingtheir grapevine orthologous genes (VvLYK5-1/2). Ourresults revealed that MAPK activation and defensegene expression were partially restored after chitintreatment by the complementation with VvLYK5-1 butnot with VvLYK5-2. These preliminary results seem toindicate that VvLYK5-1 participates in the chitinrecognition in grapevine, together with VvLYK1-1/2previously identified. Furthermore, as theperception of chitosan does not seem altered in theAtlyk5 mutant, it would also appear that theperception of chitin and chitosan does not involvethe same receptors. FRET-FLIM experimentsinitiated with these co-receptors will soon provideadditional information to better decipher themechanism of COS perception in grapevine

Recherche de récepteurs de l’immunité des plantes et étude de l’impact de biostimulants sur leur expression et la résistance induite chez des organes sensibles

National audienceLa stimulation des défenses immunitaires des plantes représente une stratégie durable deprotection des cultures qui pourrait permettre de réduire l’utilisation de pesticides chimiquesencore trop répandue en viticulture. Son principe réside en l’application, au contact des cellulesvégétales, de molécules élicitrices détectées comme des signaux de danger par la plante. Cessignaux de dangers peuvent être de différente nature et origine comme par exemple la chitine,un chito-oligosaccharide (COS) retrouvé dans les parois fongiques. Leur détection par desrécepteurs de l’immunité entraine une cascade de signalisation complexe, conduisant àl’activation de réactions de défense et à terme à une protection accrue face aux pathogènes.Malgré des résultats encourageants obtenus avec des éliciteurs oligosaccharidiques enconditions contrôlées, l’efficacité de cette méthode de protection reste encore insuffisante surle terrain. Dans ce cadre, notre premier objectif consistera à caractériser les récepteursparticipant à la perception de ces éliciteurs COS. Pour cela, une double approche decomplémentation de mutants d’Arabidopsis et d’édition génomique CRISPR-Cas9 sur vignepermettra d’évaluer l’impact d’une perte/gain de fonction. Pour tenter de comprendre ladifférence d’efficacité observée entre les conditions naturelles et expérimentales, un secondobjectif sera d’analyser l’expression de ces récepteurs en fonction des organes et des stades dedéveloppement de la plante. Enfin, nous vérifierons si l’utilisation de produits de biostimulationpour améliorer l’état physiologique de la plante peut moduler l’expression des récepteurs enquestion et ainsi permettre d’améliorer la résistance induite en réponse à ce type d’éliciteurs

Study of the stress-related signalling of endoplasmic reticulum in grapevine immunity associated to LysM receptor kinases (VvLYKs)

National audienceIn the actual situation of decreasing the use of chemicals in agriculture, enhancing our understanding of plant immunity is a critical task to develop more sustainable plant health protection methods. An interesting strategy is to study how plants, and in particular grapevine, perceives and responds to different microorganisms. Microorganisms are notably recognizedby LysM Receptor-like Kinase (LYKs) and previous works have identified 16 LYKs encoded by the grapevine genome (VvLYKs) (Roudaire et al. 2023). Among them, VvLYK1-1, VvLYK1-2 and VvLYK5-1 are involved in chitin perception and thus play a role in the plant immunity. Interestingly, immune responses are also involved during symbiotic interaction but the receptors involved in this process are still unknown. In addition, it has been demonstrated that the Unfolded Protein Response (UPR), which is activated when unfolded proteins accumulate in the endoplasmic reticulum, is also involved during the plant immune response.It’s therefore important to improve our knowledge about the role of the different grapevine LYK receptors involved in the balance between immunity and symbiosis and in addition to determine the role of stress-related signalling of endoplasmic reticulum and the consequent activation of the UPR in these two different pathways.In this context, we aim to characterize new VvLYKs involved in the perception of Myc-factors which allow the down-regulation of the plant immunity during the establishment of mycorrhizal symbiosis. In addition we also intend to characterize the UPR signalling pathways in grapevinewhich is still unknown and finally ho

Study of the stress-related signalling of endoplasmic reticulum in grapevine immunity associated to LysM receptor kinases (VvLYKs)

National audienceEnhancing our understanding of plant immunity is a critical task to develop more sustainableplant health protection methods. An interesting strategy is to study how plants, and in particulargrapevine, perceives and responds to different microorganisms. Microorganisms are notably recognized by LysM Receptor-like Kinase (LYKs) and previous works have identified 16 LYKs encoded by the grapevine genome (VvLYKs) (Roudaire et al. 2023). Among them, VvLYK1-1, VvLYK1-2 and VvLYK5-1 are involved in chitin perception and thus play a role in the plant immunity. Interestingly, immune responses are also involved during symbiotic interaction but the receptors involved in this process are still unknown. In addition, it has been demonstrated that the Unfolded Protein Response (UPR), which is activated when unfoldedproteins accumulate in the endoplasmic reticulum, is also involved during the plant immune response. It’s therefore important to improve our knowledge about the role of the different grapevine LYK receptors involved in the balance between immunity and symbiosis and in addition to determine the role of stress-related signalling of endoplasmic reticulum and the consequent activation of the UPR in these two different pathways. In this context, we aim to characterize new VvLYKs involved in the perception of Myc-factors which allow the downregulation of the plant immunity during the establishment of mycorrhizal symbiosis. In addition, we also intend to characterize the UPR signalling pathways in grapevine which is still unknown and finally how different biotic factors are involved in the stress-related signalling of endoplasmic reticulum

Cross Kingdom Immunity: The Role of Immune Receptors and Downstream Signaling in Animal and Plant Cell Death

International audienceBoth plants and animals are endowed with sophisticated innate immune systems to combat microbial attack. In these multicellular eukaryotes, innate immunity implies the presence of cell surface receptors and intracellular receptors able to detect danger signal referred as damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs). Membrane-associated pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs), C-type lectin receptors (CLRs), receptor-like kinases (RLKs), and receptor-like proteins (RLPs) are employed by these organisms for sensing different invasion patterns before triggering antimicrobial defenses that can be associated with a form of regulated cell death. Intracellularly, animals nucleotide-binding and oligomerization domain (NOD)-like receptors or plants nucleotide-binding domain (NBD)-containing leucine rich repeats (NLRs) immune receptors likely detect effectors injected into the host cell by the pathogen to hijack the immune signaling cascade. Interestingly, during the co-evolution between the hosts and their invaders, key cross-kingdom cell death-signaling macromolecular NLR-complexes have been selected, such as the inflammasome in mammals and the recently discovered resistosome in plants. In both cases, a regulated cell death located at the site of infection constitutes a very effective mean for blocking the pathogen spread and protecting the whole organism from invasion. This review aims to describe the immune mechanisms in animals and plants, mainly focusing on cell death signaling pathways, in order to highlight recent advances that could be used on one side or the other to identify the missing signaling elements between the perception of the invasion pattern by immune receptors, the induction of defenses or the transmission of danger signals to other cells. Although knowledge of plant immunity is less advanced, these organisms have certain advantages allowing easier identification of signaling events, regulators and executors of cell death, which could then be exploited directly for crop protection purposes or by analogy for medical research

The grapevine LysM receptor-like kinase VvLYK5-1 mediates chitin-triggered immunity

International audienceThe establishment of defense reactions to protect plants against invading pathogens first requiresthe recognition of Microbe-Associated Molecular Patterns (MAMPs), detected by plasmamembrane-bound Pattern Recognition Receptors (PRRs). These MAMPs, also termed elicitors, areused in several biocontrol products that are gradually developing to reduce the use of chemicalpesticides in agriculture. Chitin, the main component of fungal cell walls, as well as its deacetylatedderivative, chitosan, are two chitooligosaccharides (COS) that can be found in some of theseproducts. Unfortunately, the mechanism allowing the perception of these molecules is still poorlyunderstood in Vitis vinifera, sometimes hampering the improvement and the generalization ofthese emerging crop protection tools. On the contrary, chitin perception in the model plantArabidopsis thaliana is well described and relies on a tripartite complex formed by threemembrane-bound LysM Receptor-Like Kinases named AtLYK1/CERK1, AtLYK4 & AtLYK5, thelatter having the strongest affinity to chitin. In grapevine, COS perception has for the moment onlybeen demonstrated to rely on VvLYK1-1 & VvLYK1-2, two constitutively expressed genes that didnot specifically respond to pathogens according to genes expression analysis. In this context, weperformed experiments to complement the Arabidopsis lyk5 simple mutant and the lyk4/5 doublemutant, which showed altered response to COS, by overexpressing their grapevine orthologousgenes (VvLYK5-1/2). Our results revealed that MAPK activation and defense gene expression werepartially restored after chitin treatment by the complementation with VvLYK5-1 but not withVvLYK5-2. These preliminary results seem to indicate that VvLYK5-1 participates in the chitinrecognition in grapevine, together with VvLYK1-1 previously identified. Furthermore, as theperception of chitosan does not seem altered in the Atlyk5 mutant, it would also appear that theperception of chitin and chitosan does not involve the same receptors. FRET-FLIM experimentsinitiated with these co-receptors will soon provide additional information to better decipher themechanism of COS perception in grapevin

Development of a chitosan-based biocontrol product against crop diseases

International audienc

The grapevine LysM receptor-like kinase VvLYK5-1 mediates chitin-triggered immunity

International audienceThe establishment of defense reactions to protect plants against invading pathogens first requiresthe recognition of Microbe-Associated Molecular Patterns (MAMPs), detected by plasmamembrane-bound Pattern Recognition Receptors (PRRs). These MAMPs, also termed elicitors, areused in several biocontrol products that are gradually developing to reduce the use of chemicalpesticides in agriculture. Chitin, the main component of fungal cell walls, as well as its deacetylatedderivative, chitosan, are two chitooligosaccharides (COS) that can be found in some of theseproducts. Unfortunately, the mechanism allowing the perception of these molecules is still poorlyunderstood in Vitis vinifera, sometimes hampering the improvement and the generalization ofthese emerging crop protection tools. On the contrary, chitin perception in the model plantArabidopsis thaliana is well described and relies on a tripartite complex formed by threemembrane-bound LysM Receptor-Like Kinases named AtLYK1/CERK1, AtLYK4 & AtLYK5, thelatter having the strongest affinity to chitin. In grapevine, COS perception has for the moment onlybeen demonstrated to rely on VvLYK1-1 & VvLYK1-2, two constitutively expressed genes that didnot specifically respond to pathogens according to genes expression analysis. In this context, weperformed experiments to complement the Arabidopsis lyk5 simple mutant and the lyk4/5 doublemutant, which showed altered response to COS, by overexpressing their grapevine orthologousgenes (VvLYK5-1/2). Our results revealed that MAPK activation and defense gene expression werepartially restored after chitin treatment by the complementation with VvLYK5-1 but not withVvLYK5-2. These preliminary results seem to indicate that VvLYK5-1 participates in the chitinrecognition in grapevine, together with VvLYK1-1 previously identified. Furthermore, as theperception of chitosan does not seem altered in the Atlyk5 mutant, it would also appear that theperception of chitin and chitosan does not involve the same receptors. FRET-FLIM experimentsinitiated with these co-receptors will soon provide additional information to better decipher themechanism of COS perception in grapevin

The grapevine LysM receptor-like kinase VvLYK5-1 recognizes chitin oligomers through its association with VvLYK1-1

International audienceThe establishment of defense reactions to protect plants against pathogens requires the recognition of invasion patterns (IPs), mainly detected by plasma membrane-bound pattern recognition receptors (PRRs). Some IPs, also termed elicitors, are used in several biocontrol products that are gradually being developed to reduce the use of chemicals in agriculture. Chitin, the major component of fungal cell walls, as well as its deacetylated derivative, chitosan, are two elicitors known to activate plant defense responses. However, recognition of chitooligosaccharides (COS) in Vitis vinifera is still poorly understood, hampering the improvement and generalization of protection tools for this important crop. In contrast, COS perception in the model plant Arabidopsis thaliana is well described and mainly relies on a tripartite complex formed by the cell surface lysin motif receptor-like kinases (LysM-RLKs) AtLYK1/CERK1, AtLYK4 and AtLYK5, the latter having the strongest affinity for COS. In grapevine, COS perception has for the moment only been demonstrated to rely on two PRRs VvLYK1-1 and VvLYK1-2. Here, we investigated additional players by overexpressing in Arabidopsis the two putative AtLYK5 orthologs from grapevine, VvLYK5-1 and VvLYK5-2 . Expression of VvLYK5-1 in the atlyk4/5 double mutant background restored COS sensitivity, such as chitin-induced MAPK activation, defense gene expression, callose deposition and conferred non-host resistance to grapevine downy mildew ( Erysiphe necator) . Protein-protein interaction studies conducted in planta revealed a chitin oligomer-triggered interaction between VvLYK5-1 and VvLYK1-1. Interestingly, our results also indicate that VvLYK5-1 mediates the perception of chitin but not chitosan oligomers showing a part of its specificity

Increasing vineyard sustainability: innovating a targeted chitosan-derived biocontrol solution to induce grapevine resistance against downy and powdery mildews

The European Green Deal aims to reduce the pesticide use, notably by developing biocontrol products to protect crops from diseases. Indeed, the use of significant amounts of chemicals negatively impact the environment such as soil microbial biodiversity or groundwater quality, and human health. Grapevine (Vitis vinifera) was selected as one of the first targeted crop due to its economic importance and its dependence on fungicides to control the main damaging diseases worldwide: grey mold, downy and powdery mildews. Chitosan, a biopolymer extracted from crustacean exoskeletons, has been used as a biocontrol agent in many plant species, including grapevine, against a variety of cryptogamic diseases such as downy mildew (Plasmopara viticola), powdery mildew (Erysiphe necator) and grey mold (Botrytis cinerea). However, the precise molecular mechanisms underlying its mode of action remain unclear: is it a direct biopesticide effect or an indirect elicitation activity, or both? In this study, we investigated six chitosans with diverse degrees of polymerization (DP) ranging from low to high DP (12, 25, 33, 44, 100, and 470). We scrutinized their biological activities by evaluating both their antifungal properties and their abilities to induce grapevine immune responses. To investigate their elicitor activity, we analyzed their ability to induce MAPKs phosphorylation, the activation of defense genes and metabolite changes in grapevine. Our results indicate that the chitosans with a low DP are more effective in inducing grapevine defenses and possess the strongest biopesticide effect against B. cinerea and P. viticola. We identified chitosan with DP12 as the most efficient resistance inducer. Then, chitosan DP12 has been tested against downy and powdery mildews in the vineyard trials performed during the last three years. Results obtained indicated that a chitosan-based biocontrol product could be sufficiently efficient when the amount of pathogen inoculum is quite low and could be combined with only two fungicide treatments during whole season programs to obtain a good protection efficiency. On the whole, a chitosan-based biocontrol product could become an interesting alternative to meet the chemicals reduction targeted in sustainable viticulture