The grapevine (Vitis vinifera) LysM receptor kinases VvLYK1-1 and VvLYK1-2 mediate chitooligosaccharide-triggered immunity

Chitin, a major component of fungal cell walls, is a well-known pathogen-associated molecular pattern (PAMP) that triggers defense responses in several mammal and plant species. Here, we show that two chitooligosaccharides, chitin and chitosan, act as PAMPs in grapevine (Vitis vinifera) as they elicit immune signalling events, defense gene expression and resistance against fungal diseases. To identify their cognate receptors, the grapevine family of LysM receptor kinases (LysM-RKs) was annotated and their gene expression profiles were characterized. Phylogenetic analysis clearly distinguished three V. vinifera LysM-RKs (VvLYKs) located in the same clade as the Arabidopsis CHITIN ELICITOR RECEPTOR KINASE1 (AtCERK1), which mediates chitin-induced immune responses. The Arabidopsis mutant Atcerk1, impaired in chitin perception, was transformed with these three putative orthologous genes encoding VvLYK1-1, -2, or -3 to determine if they would complement the loss of AtCERK1 function. Our results provide evidence that VvLYK1-1 and VvLYK1-2, but not VvLYK1-3, functionally complement the Atcerk1 mutant by restoring chitooligosaccharide-induced MAPK activation and immune gene expression. Moreover, expression of VvLYK1-1 in Atcerk1 restored penetration resistance to the non-adapted grapevine powdery mildew (Erysiphe necator). On the whole, our results indicate that the grapevine VvLYK1-1 and VvLYK1-2 participate in chitin- and chitosan-triggered immunity and that VvLYK1-1 plays an important role in basal resistance against E. necator

Etude du mode d’action de l’acide β-aminobutyrique (BABA), un stimulateur des réactions de défense, sur l’homéostasie du fer chez Arabidopsis thaliana

SPE IPM CT non renseigné car non soutenu par INRAMaste

Identification of arbuscular mycorrhiza-inducible Nitrate Transporter 1/Peptide Transporter Family (NPF) genes in rice

SPE IPM UBInternational audienceArbuscular mycorrhizal fungi (AMF) colonize up to 90% of all land plants and facilitate the acquisition of mineral nutrients by their hosts. Inorganic orthophosphate (Pi) and nitrogen (N) are the major nutrients transferred from the fungi to plants. While plant Pi transporters involved in nutrient transfer at the plant-fungal interface have been well studied, the plant N transporters participating in this process are largely unknown except for some ammonium transporters (AMT) specifically assigned to arbuscule-colonized cortical cells. In plants, many nitrate transporter 1/peptide transporter family (NPF) members are involved in the translocation of nitrogenous compounds including nitrate, amino acids, peptides and plant hormones. Whether NPF members respond to AMF colonization, however, is not yet known. Here, we investigated the transcriptional regulation of 82 rice (Oryza sativa) NPF genes in response to colonization by the AMF Rhizophagus irregularis in roots of plants grown under five different nutrition regimes. Expression of the four OsNPF genes NPF2.2/PTR2, NPF1.3, NPF6.4 and NPF4.12 was strongly induced in mycorrhizal roots and depended on the composition of the fertilizer solution, nominating them as interesting candidates for nutrient signaling and exchange processes at the plant-fungal interface

The xyloglucans : are they new elicitors of <em>Arabidopsis thaliana</em> immunity ?

National audienceDamaged-Associated Molecular Patterns (DAMPs) are endogenous molecules released from the plant cell wall after wounding by pathogens. DAMPs are recognized by Pattern- Recognition Receptors (PRRs) that play a key role in plant immunity by mediating defense responses. The plant cell wall-derived oligogalacturonides (OG) are well characterized DAMPs that elicit plant immune responses such as MAPK activation, [Ca2+]cyt variations, H2O2 production, defense-related gene expression and enhanced resistance against Botrytis cinerea. Our study focused on a new polysaccharide component of the plant cell wall called xyloglucans (Xh) and compared the immune events triggered by OG and Xh in Arabidopsis thaliana. Our results indicated that Xh can be considered as new elicitors as they induced MAPK activation, the expression of defense-related genes, callose deposition and triggered immunity against Botrytis cinerea. By using a genetic approach, our data indicated that the Xh-triggered immunity against B. cinerea requires the phytoalexin and jasmonic aciddependent pathways

The xyloglucans : are they new elicitors of Arabidopsis thaliana immunity ?

Damaged-Associated Molecular Patterns (DAMPs) are endogenous molecules released from the plant cell wall after wounding by pathogens. DAMPs are recognized by Pattern- Recognition Receptors (PRRs) that play a key role in plant immunity by mediating defense responses. The plant cell wall-derived oligogalacturonides (OG) are well characterized DAMPs that elicit plant immune responses such as MAPK activation, [Ca2+]cyt variations, H2O2 production, defense-related gene expression and enhanced resistance against Botrytis cinerea. Our study focused on a new polysaccharide component of the plant cell wall called xyloglucans (Xh) and compared the immune events triggered by OG and Xh in Arabidopsis thaliana. Our results indicated that Xh can be considered as new elicitors as they induced MAPK activation, the expression of defense-related genes, callose deposition and triggered immunity against Botrytis cinerea. By using a genetic approach, our data indicated that the Xh-triggered immunity against B. cinerea requires the phytoalexin and jasmonic aciddependent pathways

Are the xyloglucans new elicitors of plant immunity ?

National audienc

Photosynthesis mediates expression of Sorghum bicolor transporters in arbuscular mycorrhizal symbiosis

National audienc

The plant resistance inducer β-aminobutyric acid (BABA) induces an iron deficiency response in A. thaliana

National audienceβ-aminobutyric acid (BABA) is a well-known plant resistance inducer. However, the molecular mechanisms underlying its effects are poorly understood. In the present study, we investigated whether BABA could act through the modification of iron homeostasis in Arabidopsis thaliana. Supporting this assumption, we obtained first evidences that BABA chelates iron with high affinity. We showed that pre-treatment of plants with BABA induced a drastic but transient iron deficiency response. Quantification of iron indicated that this response is related to the perturbation of iron distribution/availability rather than a reduction of iron assimilation. Finally, we provided evidence that the iron deficiency response triggered by BABA could be one of the determinants of its protective effects against Botrytis cinerea

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

Impact of UV Irradiation on the Chitosan Bioactivity for Biopesticide Applications

International audienceChitosan is known for its antimicrobial and antifungal properties that make it a promising candidate for plant protection. However, when sprayed in open fields, the bioactivity of chitosan significantly diminishes, suggesting a possible influence of sunlight on chitosan structure. This study aimed to investigate the effects of UV radiation, by using artificial UV sources simulating sunlight, on the stability of chitosan. A powdered chitosan with a low polymerization degree was selected and analyzed using various physicochemical methods, both before and after irradiation. Some minor differences appeared. UV spectra analysis revealed the disappearance of initially present chromophores and the emergence of a new band around 340 nm, potentially indicating the formation of carbonyl compounds. However, elemental analysis, MALDI-TOF spectra, polymerization degree, and infrared spectra did not exhibit any clear structural modifications of chitosan. Interestingly, irradiated powdered chitosan samples maintained their bioactivity, including their eliciting and antifungal properties. In the case of grapevine, irradiated chitosan demonstrated effectiveness in controlling grapevine diseases such as downy mildew, contradicting the assumption that sunlight is responsible for the decreased effectiveness of chitosan in open field conditions