Establishment of tools for investigating pyoverdine impact on iron homeostasis and plant defense responses

Iron, the fourth major element in the Earth crust, is essential for growth and development of living organisms. However, due to its low solubility in the soil, it is weakly available for plants and micro-organisms. To efficiently assimilate iron, living organisms have evolved specific strategies. In plants such as Arabidopsis thaliana three trans-membrane proteins are involved in iron assimilation while in bacteria such as Pseudomonas fluorescens iron is taken up from the soil thanks to molecules displaying high affinity for iron called siderophores. It has been recently shown that pyoverdine, the major siderophore of the beneficial bacterium Pseudomonas fluorescens, is assimilated by A. th…

The Pseudomonas fluorescens Siderophore Pyoverdine Weakens Arabidopsis thaliana Defense in Favor of Growth in Iron-Deficient Conditions

SPE EA BIOME IPM UB INRA; International audience; Pyoverdines are siderophores synthesized by fluorescent Pseudomonas spp. Under iron-limiting conditions, these high-affinity ferric iron chelators are excreted by bacteria in the soil to acquire iron. Pyoverdines produced by beneficial Pseudomonas spp. ameliorate plant growth. Here, we investigate the physiological incidence and mode of action of pyoverdine from Pseudomonas fluorescens C7R12 on Arabidopsis (Arabidopsis thaliana) plants grown under iron-sufficient or iron-deficient conditions. Pyoverdine was provided to the medium in its iron-free structure (apo-pyoverdine), thus mimicking a situation in which it is produced by bacteria. Rema…

NO signaling in cryptogein-induced immune responses in tobacco

NO signaling in cryptogein-induced immune responses in tobacco

SPEIPM; International audience

Les protéines S-nitrosylées lors des réponses de défense des plantes. Cas de la protéine CDC48 et de l’EPSP Synthase

Rapport de stage de Master 2 Recherche en Biochimie Biologie Cellulaire et Moléculaire (BBCM) SPE IPM CT non renseigné car non soutenu par INRA; Master

La pyoverdine, un sidérophore produit par la souche bénéfique du sol Pseudomonas fluorescens C7R12, impacte l’homéostasie du fer et promeut la croissance aux dépens des réactions de défense d’Arabidopsis thaliana cultivée en condition de carence en fer

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…

Investigation of the physiological impact and the mode of action of the pyoverdine from Pseudomonas fluorescens on Arabidopsis thaliana : links with iron homeostasis, growth and defense

Siderophores are strong iron chelators produced by bacteria under iron deficiency conditions. In the present work, we studied the impact of the siderophore pyoverdine, produced by the plant growth promoting rhizobacteria Pseudomonas fluorescens C7R12, on plant physiology from phenotypic to molecular effects with a specific focus on plant growth, immune response and iron homeostasis. Based on our analysis of the mode of action of the non-protein amino acid β-aminobutyric acid (BABA), a priming inducer in plants, we studied more specifically the functional link between iron homeostasis and plant immunity. Under iron deficiency, P. fluorescens excretes the iron free form of pyoverdine (apo-pyo…

There's More to the Picture Than Meets the Eye: Nitric Oxide Cross Talk with Ca2+ Signaling

Abstract Calcium and nitric oxide (NO) are two important biological messengers. Increasing evidence indicates that Ca2+ and NO work together in mediating responses to pathogenic microorganisms and microbe-associated molecular patterns. Ca2+ fluxes were recognized to account for NO production, whereas evidence gathered from a number of studies highlights that NO is one of the key messengers mediating Ca2+ signaling. Here, we present a concise description of the current understanding of the molecular mechanisms underlying the cross talk between Ca2+ and NO in plant cells exposed to biotic stress. Particular attention will be given to the involvement of cyclic nucleotide-gated ion channels and…

NO signaling in plant immunity: A tale of messengers

International audience; Nitric oxide (NO) is a free radical gas involved in a myriad of plant physiological processes including immune responses. How NO mediates its biological effects in plant facing microbial pathogen attack is an unresolved question. Insights into the molecular mechanisms by which it propagates signals reveal the contribution of this simple gas in complex signaling pathways shared with reactive oxygen species (ROS) and the second messenger Ca2+. Understanding of the subtle cross-talks operating between these signals was greatly improved by the recent identification and the functional analysis of proteins regulated through S-nitrosylation, a major NO-dependent post-transl…

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…