Are diacylglycerol-kinases involved in cryptogein-induced early signaling events?

SPE IPM; National audience

Perception of elicitins by receptor complex in solanaceae

Extensive infections of crop plants by plant pathogens have repeatedly resulted in catastrophic harvest failures causing major economic and social problems worldwide. Successful plant defence against pathogens is based on early microbe recognition and fast activation of downstream immune signalling (e.g. phosphorylations, production of reactive oxygen species, transcriptomic reprogramming). Plant surface pattern-recognition receptors (PRRs) act as initial detectors that can recognise microbial-associated molecular patterns (MAMPs) to induce the basal resistance response called MAMP-triggered immunity (MTI). Despite the increasing number of PRRs discovered in the past 20 years, for most of t…

Proteasome comprising a beta1 inducible subunit acts as a negative regulator of NADPH oxidase during elicitation of plant defense reactions.

Elicitation of defense reactions in tobacco by cryptogein, triggered a production of active oxygen species (AOS) via the NADPH oxidase, NtrbohD, and an accumulation of beta1din, a defense induced beta-type subunit of 20S proteasome. The proteasome inhibitor, MG132, stimulated this AOS production. Tobacco cells transformed with sense constructs of beta1din showed an inhibition of the AOS production following elicitin treatment, whereas the antisense transformed cells showed a strongly enhanced AOS production. In cells transformed with sense construct of beta1din, the NtrbohD transcripts failed to be induced by cryptogein as observed in control and antisense transformed cells. Conversely, in …

Rôle de la dynamique de la membrane plasmique dans la mise en place des réactions de défense chez le tabac

The binding of cryptogein, a plant defense elicitor secreted by an oomycete, to an unknown receptor triggers well-known biochemical events of early signal transduction at the plasma membrane of tobacco cells. One of these early events is the transient production of Reactive Oxygen Species (ROS) by an NADPH oxidase, NtrbohD. We were thus interested to analyze the dynamic of the plasma membrane during these early stages. We determined that internalization of the endocytotic marker FM4-64 is stimulated a few minutes after addition of cryptogein to tobacco BY-2 cells. This stimulation is specific to the signal transduction pathway elicited by cryptogein since a lipid transfer protein, which bin…

Les couverts végétaux. Un atout majeur pour réduire les intrants de synthèse et augmenter les services écosystémiques au vignoble

International audience; De manière générale, un couvert végétal se définit par une espèce ou une communauté d’espèces végétales recouvrant le sol de manière permanente ou temporaire. L’agriculteur a la possibilité de semer ces couverts, selon un choix raisonné, ou bien de laisser la végétation spontanée se développer. Il existe 3 types de couverts semés avec des objectifs différents pour l’exploitant : le couvert hivernal, installé pour faire face au phénomène d’érosion du sol important pendant cette période de repos végétatif ; les engrais verts, installés avec l’objectif d’amender naturellement la parcelle, en détruisant et en enfouissant les résidus du couvert qui libèrent ainsi de la ma…

Interplays between nitric oxide and reactive oxygen species in cryptogein signalling

The cellular messenger nitric oxide (NO) has many functions in plants. In this study, we investigated its interplays with Reactive Oxygen Species (ROS) in the defense responses triggered by the elicitin cryptogein produced by the oomycete Phytophthora cryptogea. The production of NO induced by cryptogein in tobacco cell suspensions was partly regulated through a ROS-dependent pathway involving the NADPH oxidase NtRBOHD. In turn, NO down-regulated the level of H2O2 derived from NtRBOHD activity. Both NO and ROS synthesis appeared to be under the control of two redundant isoforms of histone deacetylases of type 2 acting as negative regulators of cell death. Occurrence of an interplay between …

Quantitative proteomics reveals a dynamic association of proteins to detergent-resistant membranes upon elicitor signaling in tobacco.

International audience; A large body of evidence from the past decade supports the existence, in membrane from animal and yeast cells, of functional microdomains playing important roles in protein sorting, signal transduction, or infection by pathogens. In plants, as previously observed for animal microdomains, detergent-resistant fractions, enriched in sphingolipids and sterols, were isolated from plasma membrane. A characterization of their proteic content revealed their enrichment in proteins involved in signaling and response to biotic and abiotic stress and cell trafficking suggesting that these domains were likely to be involved in such physiological processes. In the present study, w…

NADPH Oxidase-Mediated Reactive Oxygen Species Production: Subcellular Localization and Reassessment of Its Role in Plant Defense

International audience; Chemiluminescence detection of reactive oxygen species (ROS) triggered in tobacco BY-2 cells by the fungal elicitor cryptogein was previously demonstrated to be abolished in cells transformed with an antisense construct of the plasma membrane NADPH oxidase, NtrbohD. Here, using electron microscopy, it has been confirmed that the first hydrogen peroxide production occurring a few minutes after challenge of tobacco cells with cryptogein is plasma membrane located and NtrbohD mediated. Furthermore, the presence of NtrbohD in detergent-resistant membrane fractions could be associated with the presence of NtrbohD-mediated hydrogen peroxide patches along the plasma membran…

Internalisation de la cryptogéine dans des cellules de tabac Nicotiana tabacum, cv Bright Yellow 2 (BY-2)

SPEBAPIPMUBINRA; Internalisation de la cryptogéine dans des cellules de tabac [i]Nicotiana tabacum[/i], cv Bright Yellow 2 (BY-2). 7. Journées Scientifiques et Techniques du Réseau des Microscopistes de l'INRA (RμI)

Dynamics of sugar transports in tobacco-microbe interactions

Rôle des microdomaines du plasmalemme dans la réponse de la cellule végétale au stress biotique

National audience

The Plant Defense Elicitor Cryptogein Stimulates Clathrin-Mediated Endocytosis Correlated with Reactive Oxygen Species Production in Bright Yellow-2 Tobacco Cells  

Abstract The plant defense elicitor cryptogein triggers well-known biochemical events of early signal transduction at the plasma membrane of tobacco (Nicotiana tabacum) cells, but microscopic observations of cell responses related to these early events were lacking. We determined that internalization of the lipophilic dye FM4-64, which is a marker of endocytosis, is stimulated a few minutes after addition of cryptogein to tobacco Bright Yellow-2 (BY-2) cells. This stimulation is specific to the signal transduction pathway elicited by cryptogein because a lipid transfer protein, which binds to the same receptor as cryptogein but without triggering signaling, does not increase endocytosis. To…

Characterization of membrane structure modifications induced during plant defense signaling

SPEIPMUBINRADOCT; Plasma membrane was long considered as a simple separation between internal and external cellular environment. But more, it is a dynamic interface, an exchange platform. Now, recent researches highlight its role in plant defense responses to biotic and abiotic stresses. We use the tobaccocryptogein model to study the early steps of plant cell responses to pathogen detection. The signaling cascade includes an oxidative burst triggering an increase of plasma membrane order. The level of membrane order informs us about both packing and arrangement of membrane components, this parameter being evaluated by spectrofluorimetric approaches using a lipidic environment-sensitive pro…

La Nuit Européenne des Chercheur(e)s 2020 à Dijon propose trois activités « on line » autour de notre thème « Petits secrets Nocturnes. Les "Experts Agroécologie " Pierre-Emmanuel Courty et Jérôme Fromentin mèneront une enquête stupéfiante pour "association de bienfaiteurs", au cœur d'une scène de crime mêlant symbiose mycorhizienne et truffes...

National audience; La Nuit Européenne des Chercheur(e)s 2020 propose trois activités « on line » autour de notre thème « Petits secrets Nocturnes »: Les "Experts à Dijon" Pierre-Emmanuel Courty et Jérôme Fromentin (UMR Agroécologie) mèneront une enquête stupéfiante pour "association de bienfaiteurs", au cœur d'une scène de crime mêlant symbiose mycorhizienne et truffes...

Impact of double symbiosis (arbuscular mycorrhiza and nodulation) on nitrogen uptake in the Papilionoideae subfamily

The study of plant-microbe associations through nutrient exchanges has significantly improved our understanding of plant microbiome. Leguminous plants establish mutualistic associations with both rhizobial bacteria and arbuscular mycorrhizal fungi. These symbioses improve mineral plant nutrition and increase plant resistance against biotic and abiotic stresses. Plant-microbe associations provide key features for the current agricultural and environmental challenges.In Poaceae plant, inductions of specific ammonium transporters (AMT) genes and nitrogen/peptide transporters (NRF) genes have already been described during arbuscular mycorrhiza symbiosis. Similarly, in Papilionoideae, AMT and NR…

Asymétrie de la membrane plasmique végétale : caractérisation et rôle dans la signalisation immunitaire des plantes

National audience; La membrane plasmique (MP) forme une barrière sélective entre la cellule et le milieu extérieur.C’est un senseur des modifications environnementales et une plateforme orchestrant latransduction du signal permettant de déployer une réponse adaptée. Elle joue donc un rôleessentiel dans la physiologie cellulaire. Décrypter les bases moléculaires de l’organisation dela MP apparaît donc nécessaire pour comprendre comment les plantes s’adaptent auxmodifications environnementales. La MP est une bicouche de lipides à laquelle des protéinessont associées, et les données accumulées sur ce modèle ont révélé son organisation complexeet dynamique et le rôle essentiel joué par les lipi…

Rac regulation of NtrbohD, the oxidase responsible for the oxidative burst in elicited tobacco cell

Five cDNAs encoding Rac protein homologues to the Rho-related proteins from plants (Rop) were isolated in tobacco, and the function of one of them, Ntrac5, was studied. The Ntrac5 mRNA is repressed when tobacco leaves and cells are treated with the fungal elicitor cryptogein. Tobacco cells were transformed with sense constructs of Ntrac5 or Ntrac5V15, encoding the native GTP/GDP-bound form of this Rac protein homologue or the constitutively active mutant in its GTP-bound form, respectively. Immunological studies indicate that the corresponding protein is continuously located on the plasma membrane (PM). Both types of transformed cells show the same extra-cellular alkalinization as the contr…

Internalization of the a defense elicitor into Nicotiana tabacum cells, cv Bright Yellow 2 (BY-2)

Regulation of reactive oxygen species production by a 14-3-3 protein in elicited tobacco cells.

International audience; The regulation of the system responsible for the production of reactive oxygen species (ROS) during plant–microorganism interaction is still largely unknown. The protein NtrbohD has been recently demonstrated as the plasma membrane oxidase responsible for ROS production in elicited tobacco cells. Here, its C-terminus part was used as a bait in a two-hybrid screen in order to identify putative regulators of this system. This led to the isolation of a cDNA coding for a member of the 14-3-3 protein family. The corresponding transcript was induced after infiltration of tobacco leaves with the fungal elicitor cryptogein. Tobacco cells transformed with an antisense constru…