Perception of pathogenic or beneficial bacteria and their evasion of host immunity: pattern recognition receptors in the frontline

International audience; Plants are continuously monitoring the presence of microorganisms to establish an adapted response. Plants commonly use pattern recognition receptors (PRRs) to perceive microbe- or pathogen-associated molecular patterns (MAMPs/PAMPs) which are microorganism molecular signatures. Located at the plant plasma membrane, the PRRs are generally receptor-like kinases (RLKs) or receptor-like proteins (RLPs). MAMP detection will lead to the establishment of a plant defense program called MAMP-triggered immunity (MTI). In this review, we overview the RLKs and RLPs that assure early recognition and control of pathogenic or beneficial bacteria. We also highlight the crucial func…

Sugar exchanges in arbuscular mycorrhiza: RiMST5 and RiMST6, two novel Rhizophagus irregularis monosaccharide transporters, are involved in both sugar uptake from the soil and from the plant partner

SPE IPM INRA UB CT1; International audience; Arbuscular mycorrhizal (AM) fungi are associated with about 80% of land plants. AM fungi provide inorganic nutrients to plants and in return up to 20% of the plant-fixed CO2 is transferred to the fungal symbionts. Since AM fungi are obligate biotrophs, unraveling how sugars are provided to the fungus partner is a key for understanding the functioning of the symbiosis. In this study, we identified two new monosaccharide transporters from Rhizophagus irregularis (RiMST5 and RiMST6) that we characterized as functional high affinity monosaccharide transporters. RiMST6 was characterized as a glucose specific, high affinity H(+) co-transporter. We prov…

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

The 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, sometime…

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 INRA; Master

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

SPE IPM UB CNRS Agrosup

Are the xyloglucans new elicitors of plant 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 t…

Sugar exchanges in arbuscular mycorrhiza : Characterization and role of two new monosaccharide transporters from the model fungus Rhizophagus irregularis

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

β-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 defic…

Development of a chitosan-based biocontrol product against crop diseases

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 audience; La 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 …

Photosynthesis mediates expression of Sorghum bicolor transporters in arbuscular mycorrhizal symbiosis

β-Aminobutyric Acid (BABA)-Induced Resistance in Arabidopsis thaliana: Link with Iron Homeostasis

International audience; Bêta-Aminobutyric acid (BABA) is a nonprotein amino acid inducing resistance in many different plant species against a wide range of abiotic and biotic stresses. Nevertheless, how BABA primes plant natural defense reactions remains poorly understood. Based on its structure, we hypothesized and confirmed that BABA is able to chelate iron (Fe) in vitro. In vivo, we showed that it led to a transient Fe deficiency response in Arabidopsis thaliana plants exemplified by a reduction of ferritin accumulation and disturbances in the expression of genes related to Fe homeostasis. This response was not correlated to changes in Fe concentrations, suggesting that BABA affects the…