Analysis of the role of nitric oxide (NO) in the cross‐regulation between immunity, growth and iron homeostasis in plants

Studies performed in our Agroecology Department show that the immune response of plants is linked to their iron nutrition and is modulated by pyoverdine, a siderophore produced by the plant beneficial rhizobacteria Pseudomonas fluorescens C7R12. Accordingly, Arabidopsis thaliana plantlets exposed to iron deficiency and treated with pyoverdine in its iron non‐chelated structure (apo‐pyo) show an enhanced growth but a decreased immune response capacity. We hypothesize that nitric oxide (NO), a universal signaling molecule, is a key component of the regulation of the immune response in plants exposed to apo‐pyo and to the C7R12 strain. We checked by fluorescence microscopy that NO is actually …

New insights about the role of the chaperon-like protein Cdc48, a target for nitric oxide in plant immunity

NO signaling in cryptogein-induced immune responses in tobacco

NO signaling in cryptogein-induced immune responses in tobacco

SPEIPM; International audience

Identification et analyse du rôle de protéines S‐nitrosylées lors de la modulation de la réponse immunitaire d’Arabidopsis thaliana par l’apo-pyoverdine produite par la souche bactérienne bénéfique Pseudomonas fluorescens C7R12

Des travaux de l’UMR Agroécologie montrent que la réponse immunitaire des plantes est corrélée à leur nutrition en fer et est modulable par la pyoverdine, un sidérophore produit par la souche bactérienne bénéfique Pseudomonas fluorescens C7R12. Le traitement d’Arabidopsis thaliana exposée à une carence en fer par la pyoverdine dépourvue de fer (apo-pyo) restaure en effet la croissance de la plante aux dépens de son immunité. Nous avons émis l’hypothèse que le monoxyde d’azote (NO), une molécule signalétique ubiquitaire, est un acteur de la modulation de la réponse immunitaire des plantes exposées à l’apo-pyo et à sa souche productrice. Afin d’étayer cette hypothèse, trois axes seront dévelo…

The impact of the plant-associated siderophore ornicorrugatin on Arabidopsis thaliana

International audience; Most microorganisms produce siderophores when they are faced with iron-limiting conditions. Fluorescent pseudomonads produce a yellow-green, fluorescent siderophore, called pyoverdine. Besides pyoverdine, sev-eral other secondary siderophores, which have a relatively lower affinity for iron, have been identified in Pseu-domonas spp. Examples are pyochelin, pseudomonine and thioquinolobactin (Cornelis and Matthijs 2002). An atypical set of secondary siderophores, due to their lipopeptidic nature, are the siderophores corrugatin (Risse et al., 1998), ornicorrugatin (Matthijs et al., 2008) and histicorrugatin (Matthijs et al., 2016). These siderophores consist out of an…

Emerging functions of nitric oxide in plant immunity

SPEIPMUBAgrosupCNRS; The importance of nitric oxide (NO) in innate and adaptive immunity in mammals is well recognised. NO exerts antimicrobial properties against invaders but also displays immunoregulatory functions in which S-nitrosylation represents a signalling process of major importance. Over the last two decades, a growing body of evidence suggests that NO is also a major component of plant immunity. Our understanding of its role in plant defence has been enriched by the identification and functional analysis of S-nitrosylated proteins. The recent identification of new S-nitrosylated proteins including the chaperone-like enzyme cell division cycle 48 (CDC48), histone deacetylases (HD…

Identification and functional characterization of S-nitrosated proteins from Klebsormidium nitens, a model alga to study plant adaptation to land

The small gaseous molecule nitric oxide (NO) is well established as a major ubiquitous component of cell signalling. A key signalling mechanism mediating NO effects is S-nitrosation, a post-translational modification by which NO can impact the target protein activities, subcellular localizations, and capacities to form protein complexes. The identification of proteins targeted by NO is of major interest in order to elucidate NO functions. Interestingly, land plants lack NO synthase (NOS), which is the main enzyme for NO synthesis in metazoans, while a few algal species possess it, thus raising many interrogations. Therefore, we focused on the identification of S-nitrosated proteins during s…

Analysis of the cross‐regulation between immunity, growth and iron homeostasis in plants

The existence of a tightly regulated balance between growth and immunity in plants has recently emerged. In this study, we challenged this concept thanks to the biological model pyoverdine-Arabidopsis thaliana. Pyoverdine is a siderophore produced by the plant growth promoting rhizobacteria Pseudomonas fluorescens C7R12. Under iron deficiency, P. fluorescens excretes the iron free form of pyoverdine (apo‐pyo) in the soil. Once chelated with iron (ferri‐pyo), the complex is internalized by the bacteria. We demonstrated that Arabidopsis thaliana plants treated by apo‐pyo in a medium containing or not iron internalize pyoverdine. Interestingly, apo‐pyo-treated plants did not show a typical gro…

Science Dijon : une ambassadrice du savoir

Département SPE Pôle IPM; Chercheuse à l’Université de Bourgogne, Angélique Besson-Bard sera l’une des ambassadrices du programme “Pour les filles et la science”, destiné à promouvoir la science auprès des lycéennes.

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…

NO signaling in tobacco elicited by the MAMP cryptogein

SPEPôle IPM; International audience; During the past years, nitric oxide (NO) has been shown to be a major cell signaling messenger in plants. Its importance has been highlighted during plant responses to pathogen attack or MAMPs (microbe associated molecular patterns) and during induced resistance or priming phenomenon. The major focus of our research is to understand how nitric oxide can modulate the activity of protein involved in plant defense. We identified several proteins undergoing S-nitrosylation, a redox-based post-translational modification of proteins, in tobacco cells elicited by cryptogein, a 10 kDa protein produced by the oomycete Phytophthora cryptogea and inducing immune re…

BABA-induced resistance in Arabidopsis thaliana: Links with iron homeostasis