NO-Based Signaling in Plants

In animals, nitric oxide (NO) is an endogenously produced radical involved in cell communication and signal transduction. Its functions in plants are currently being discovered at an unprecedented pace, and insight into NO-derived mechanisms has mainly been gained from research on signal transduction. Numerous studies have firmly placed NO as one component of the signal perception–transduction network that connects plant responses to primary signals, including hormones, elicitors of defence responses or abiotic stresses. Protein kinases and the second messengers Ca 2+, cGMP, and cADPR convey part of the NO signal within cells. Furthermore, NO-based protein modifications are emerging as broa…

Le monoxyde d'azote (NO) chez les plantes. Un messager cellulaire impliqué dans la signalisation des réponses de défense - l'exemple du modèle N. tabacum / cryptogéine

Some Plant Defense Stimulators can induce IL-1β production in human immune cells in vitro

8 pages; International audience; Among Plant Protection Products (PPP), a new emerging category of pesticides act by stimulating plant defense in order to improve plant resistance against microbial pathogens. Given that these compounds, the so-called Plant Defense Stimulators (PDS) act on innate immunity, we tested, using an in vitro approach on human mononuclear leucocytes (PBMC), the potential toxicity (XTT assay) and inflammatory effects (production of IL-1β) of 4 PPP belonging to different chemical families. We found that two products (LBG-01F34® and Regalis®) did not induce any cytotoxicity or IL-1 β production. The product BION-50 WG®, that contains Acibenzolar-S-methyl (ASM) and sili…

The Medicago truncatula sucrose transporter family: characterization and implication of key members in carbon partitioning towards arbuscular mycorrhizal fungi.

We identified de novo sucrose transporter (SUT) genes involved in long-distance transport of sucrose from photosynthetic source leaves towards sink organs in the model leguminous species Medicago truncatula. The iden- tification and functional analysis of sugar transporters provide key information on mechanisms that underlie carbon partitioning in plant-microorganism interactions. In that way, full-length sequences of the M. truncatula SUT (MtSUT) family were retrieved and biochemical characterization of MtSUT members was performed by heterologous expression in yeast. The MtSUT family now comprises six genes which distribute among Dicotyledonous clades. MtSUT1-1 and MtSUT4-1 are key members…

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

The glutaredoxin ATGRXS13 is required to facilitate Botrytis cinerea infection of Arabidopsis thaliana plants

Summary Botrytis cinerea is a major pre- and post-harvest necrotrophic pathogen with a broad host range that causes substantial crop losses. The plant hormone jasmonic acid (JA) is involved in the basal resistance against this fungus. Despite basal resistance, virulent strains of B. cinerea can cause disease on Arabidopsis thaliana and virulent pathogens can interfere with the metabolism of the host in a way to facilitate infection of the plant. However, plant genes that are required by the pathogen for infection remain poorly described. To find such genes, we have compared the changes in gene expression induced in A. thaliana by JA with those induced after B. cinerea using genome-wide micr…

Nitric oxide inhibits the ATPase activity of the chaperone-like AAA+ ATPase CDC48, a target for S-nitrosylation in cryptogein signalling in tobacco cells

NO has important physiological functions in plants, including the adaptative response to pathogen attack. We previously demonstrated that cryptogein, an elicitor of defence reaction produced by the oomycete Phytophthora cryptogea , triggers NO synthesis in tobacco. To decipher the role of NO in tobacco cells elicited by cryptogein, in the present study we performed a proteomic approach in order to identify proteins undergoing S-nitrosylation. We provided evidence that cryptogein induced the S-nitrosylation of several proteins and identified 11 candidates, including CDC48 (cell division cycle 48), a member of the AAA+ ATPase (ATPase associated with various cellular activities) family. In vit…

Mechanisms of nitric-oxide-induced increase of free cytosolic Ca2+ concentration in Nicotiana plumbaginifolia cells.

In this study, we investigated a role for nitric oxide (NO) in mediating the elevation of the free cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) in plants using Nicotiana plumbaginifolia cells expressing the Ca(2+) reporter apoaequorin. Hyperosmotic stress induced a fast increase of [Ca(2+)](cyt) which was strongly reduced by pretreating cell suspensions with the NO scavenger carboxy PTIO, indicating that NO mediates [Ca(2+)](cyt) changes in plant cells challenged by abiotic stress. Accordingly, treatment of transgenic N. plumbaginifolia cells with the NO donor diethylamine NONOate was followed by a transient increase of [Ca(2+)](cyt) sensitive to plasma membrane Ca(2+) channel inhibitors …

NO signaling in cryptogein-induced immune responses in tobacco

NO signaling in cryptogein-induced immune responses in tobacco

SPEIPM; International audience

Protein S-nitrosylation: specificity and identification strategies in plants

SPE Pôle IPM UB; International audience; The role of nitric oxide (NO) as a major regulator of plant physiological functions has become increasingly evident. To further improve our understanding of its role, within the last few years plant biologists have begun to embrace the exciting opportunity of investigating protein S-nitrosylation, a major reversible NO-dependent post-translational modification (PTM) targeting specific Cys residues and widely studied in animals. Thanks to the development of dedicated proteomic approaches, in particular the use of the biotin switch technique (BST) combined with mass spectrometry, hundreds of plant protein candidates for S-nitrosylation have been identi…

S-nitrosylation: An emerging post-translational protein modification in plants

International audience; Increasing evidences support the assumption that nitric oxide (NO) acts as a physiological mediator in plants. Understanding its pleiotropic effects requires a deep analysis of the molecular mechanisms underlying its mode of action. In the recent years, efforts have been made in the identification of plant proteins modified by NO at the post-translational level, notably by S-nitrosylation. This reversible process involves the formation of a covalent bond between NO and reactive cysteine residues. This research has now born fruits and numerous proteins regulated by S-nitrosylation have been identified and characterized. This review describes the basic principle of S-n…

Nitric oxide production in tobacco leaf cells: a generalized stress response?

The function of nitric oxide (NO), a gaseous free radical emitted by many plants, is incompletely understood. In the present study the hypothesis that NO generation, like that of the reactive oxygen species, occurs as a general response to different environmental cues was tested. Leaf peels and mesophyll cell suspensions of Nicotiana tabacum cv. Xanthi were loaded with the NO-specific fluorophore, diaminofluorescein, and subjected to an abiotic stressor. Light stress and mechanical injury had no apparent effect on NO production. In contrast, high temperatures, hyperosmotic stress, salinity and epi-illumination in a microscope all led to rapid surges in NO-induced fluorescence. The fluoresce…

Cross-Talk between ROS and Calcium in Regulation of Nuclear Activities

International audience; Calcium and Reactive Oxygen Species (ROS) are acknowledged as crucial second messengers involved in the response to various biotic and abiotic stresses. However, it is still not clear how these two compounds can play a role in different signaling pathways leading the plant to a variety of processes such as root development or defense against pathogens. Recently, it has been shown that the concept of calcium and ROS signatures, initially discovered in the cytoplasm, can also be extended to the nucleus of plant cells. In addition, it has been clearly proved that both ROS and calcium signals are intimately interconnected. How this cross-talk can finally modulate the tra…

Plant iNOS: conquest of the Holy Grail

In animals, nitric oxide (NO) is produced by a family of enzymes named nitric oxide synthases (NOSs). Although no NOS-like gene has been found in the Arabidopsis thaliana genome, biochemical studies have suggested that a NOS-like protein is likely to be activated in plants resisting pathogens. This protein has been recently identified as a variant P protein of glycine decarboxylase. This discovery means that studies of nitric oxide signalling functions in plants are now entering a new phase.

Proteinaceous and oligosaccharidic elicitors induce different calcium signatures in the nucleus of tobacco cells.

We previously reported elevated cytosolic calcium levels in tobacco cells in response to elicitors [D. Lecourieux, C. Mazars, N. Pauly, R. Ranjeva, A. Pugin, Analysis and effects of cytosolic free calcium elevations in response to elicitors in Nicotiana plumbaginifolia cells, Plant Cell 14 (2002) 2627-2641]. These data suggested that in response to elicitors, Ca2+, as a second messenger, was involved in both systemic acquired resistance (RSA) and/or hypersensitive response (HR) depending on calcium signature. Here, we used transformed tobacco cells with apoaequorin expressed in the nucleus to monitor changes in free nuclear calcium concentrations ([Ca2+](nuc)) in response to elicitors. Two …

Post-Translational Modifications of Nuclear Proteins in the Response of Plant Cells to Abiotic Stresses

For a long time, in plant cells as in animal cells, the nucleus was only considered as the organelle in which fundamental mechanisms such as replication and transcription occurred. While strong efforts were deployed in order to identify important families of transcription factors such as MYB, WRKY or TGA families (Dubos et al., 2010; Rushton et al., 2010), a few attention was devoted to our lack of knowledge about their regulation in regard to the physiological conditions of the plant cells. Whereas the major importance of posttranslational modification of proteins is well established for several decades regarding cytosolic proteins, the last years have been characterized by the discovery t…

Evolutionary diversification of type-2 HDAC structure, function and regulation in Nicotiana tabacum

Ministère de l'Education Nationale et de la Recherche ; Conseil Régional de Bourgogne (PARI AGRALE8) ; Association pour la Recherche sur les Nicotianacées ; Conseil Régional de Bourgogne; International audience; Type-2 HDACs (HD2s) are plant-specific histone deacetylases that play diverse roles during development and in responses to biotic and abiotic stresses. In this study we characterized the six tobacco genes encoding HD2s that mainly differ by the presence or the absence of a typical zinc finger in their C-terminal part. Of particular interest, these HD2 genes exhibit a highly conserved intron/exon structure. We then further investigated the phylogenetic relationships among the HD2 gen…

Cryptogein-Induced Anion Effluxes

Anion effluxes are amongst the earliest reactions of plant cells to elicitors of defence responses. However, their properties and their role in disease resistance remain almost unknown. We previously demonstrated that cryptogein, an elicitor of tobacco defence responses, induces a nitrate (NO(3) (-)) efflux. This efflux is an early prerequisite to the cryptogein-triggered hypersensitive response (HR). Here, we analyzed the electrophysiological properties of the elicitor-mediated NO(3) (-) efflux and clarified the mechanisms through which it contributes to cell death. Application of the discontinuous single electrode voltage-clamp technique in tobacco cells elicited with cryptogein enabled u…

Le monoxyde d’azote

Le monoxyde d’azote (NO) est un mediateur physiologique associe a divers processus chez les animaux, dont l’immunite. Des travaux conduits recemment montrent que les plantes, confrontees a l’attaque d’agents pathogenes, produisent egalement du NO. Le NO est donc un acteur des voies de signalisation cellulaire activees en reponse a la reconnaissance par les plantes d’agresseurs exterieurs. L’etude des molecules cibles du NO et, plus particulierement, la caracterisation de proteines S-nitrosylees, a permis d’avoir un premier apercu des mecanismes fins inherents a ses fonctions. Le NO serait ainsi implique dans l’activation ainsi que dans la desensibilisation des voies de signalisation mobilis…

Plant responses to biotic/abiotic stresses: lessons from cell signalin

prod 2017-284a SPE IPM UB AGROSUP CNRS CT; International audience; About this Research Topic : Facing up to stressful conditions imposed by their environment that could affect their growth and their development throughout their life cycle, plants must be able to perceive, to process and to translate different stimuli into adaptive responses. From a human point of view, knowledge about plant stress response is also vital for the development of breeding and biotechnological strategies to improve stress tolerance in crops. Understanding the organism-coordinated responses involves fine description of the mechanisms occurring at the cellular and molecular level. These mechanisms involve numerous…

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…

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

SPE IPM UB CNRS Agrosup

Effect of commercially available Plant Defence Stimulators on human innate immunity

PDS (Plant defence stimulators) constitute a recent alternative to pesticides used for crop protection. These compounds are of diverse nature, they all act by stimulating plant innate immune system and plants can better fight pathogens. There are many similarities in pathogen perception systems and cellular signalling in plants and animals. Many elicitors stimulate both human and plant innate immunity (Zipfel and Felix, 2005). Therefore, it is likely that human innate immunity could be modulated by PDS. The aim of this study is to evaluate pro/anti-inflammatory activity of five different commercially available PDS on human cell models. We studied the pro/anti-inflammatory effect of PDS on h…

Impact de la S-nitrosylation sur la structure des calmoduline chez les plantes

Silencing of plant defensin type 1 reduces sensitivity to pathogens and zinc toxicity in arabidopsis thaliana

Ectopic expression of defensins in plants correlates with their increased capacity to withstand abiotic and biotic stresses(Carvalho & Gomes, 2011). However, few studies have explored the effects of decreased plant endogenous defensin transcripts on these stress responses.When over-expressed in Arabidopsis thaliana, some of the seven members of thePlant Defensin type 1 family (PDF1) are recognised to improve plant responses tonecrotrophic pathogens(De Conincket al.,2010)and increase seedling tolerance to excess zinc (Zn;Mirouzeet al., 2006). We carried out an extensive physiological and biochemical comparative characterisation of i) novel transgenic amiRNA lines silenced for the five most s…

Nitric oxide (NO) in plants, a cell signalling messenger involved in plant defense. The case study of the N. tabacum / cryptogein model

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Mechanisms of Defence to Pathogens : Biochemistry and Physiology

SPE IPM; International audience; Plant defences comprise both pre-existing barriers as well as defences induced upon perception of pathogen-associated molecular patterns (PAMPs) or microbe-associated molecular patterns (MAMPs) or molecules produced from damage as a result of infection (damage-associated molecular patterns (DAMPs)). This chapter focuses on the induced mechanisms of defence. The inducibility of phytoalexin biosynthesis has probably been favoured in the course of evolution by biological constraints such as metabolic costs and functional side-effects associated with chemical defence. Historically, the term ‘hypersensitive’ refers to the rapid and localized cell death induced in…

Impact of phosphate fertilization and arbuscular mycorrhiza on the development, nutrition and quality of micropropagated walnut rootstocks.

The English walnut (Juglans regia L.) is the main species cultivated for the production of edible nuts. Due to heterozygosis, the characteristics of agronomical interest of walnut cultivars are not inherited via seed propagation. In vitro plant tissue culture thus plays a key role in mass propagation of high-quality walnut rootstocks. Micropropagation of walnut explants needs an ex vitro acclimatization phase to repair the in vitro induced abnormalities, and further requires a post-acclimatization growth in greenhouse conditions when plantlets become photoautotrophic. However, poor survival and slow growth rates are common difficulties encountered in nurseries when establishing micropropaga…

NO Signalling in Plant Immunity

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 (HDACs) and calmodulin (…

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…

USE OF 4-PHENYLBUTYRIC ACID AND/OR 3-PHENYLBUTYRIC ACID AND/OR 2-PHENYLBUTYRIC ACID IN PREVENTING AND TREATING CRYPTOGAMIC DISEASES

The present invention relates to the use of 2-phenylbutyric acid or 3-phenylbutyric acid or 4-phenylbutyric acid, or a salt thereof, or a combination thereof, to combat cryptogamic diseases which are caused by fungi or oomycetes. The present invention also relates to the use of these compounds and these combinations as fungicidal or fungistatic agents in preventing or curing cryptogamic diseases.

Arabidopsis thaliana nicotianamine synthase 4 is required for proper response to iron deficiency and to cadmium exposure.

International audience; The nicotianamine synthase (NAS) enzymes catalyze the formation of nicotianamine (NA), a non-proteinogenic amino acid involved in iron homeostasis. We undertook the functional characterization of AtNAS4, the fourth member of the Arabidopsis thaliana NAS gene family. A mutant carrying a T-DNA insertion in AtNAS4 (atnas4), as well as lines overexpressing AtNAS4 both in the atnas4 and the wild-type genetic backgrounds, were used to decipher the role of AtNAS4 in NA synthesis, iron homeostasis and the plant response to iron deficiency or cadmium supply. We showed that AtNAS4 is an important source for NA. Whereas atnas4 had normal growth in iron-sufficient medium, it dis…

Nitric oxide production mediates oligogalacturonide-triggered immunity and resistance to Botrytis cinerea in Arabidopsis thaliana

Nitric oxide (NO) regulates a wide range of plant processes from development to environmental adaptation. In this study, we investigated the production and/or function of NO in Arabidopsis thaliana leaf discs and plants elicited by oligogalacturonides (OGs) and challenged with Botrytis cinerea. We provided evidence that OGs triggered a fast and long lasting NO production which was Ca(2+) dependent and involved nitrate reductase (NR). Accordingly, OGs triggered an increase of both NR activity and transcript accumulation. NO production was also sensitive to the mammalian NO synthase inhibitor L-NAME. Intriguingly, we showed that L-NAME affected NO production by interfering with NR activity, t…

Effect of commercially available Plant Defence Stimulators (PDS) on human innate immunity

PDS (Plant defence stimulators) constitute a recent alternative to pesticides used for crop protection. These compounds called elicitors are of diverse nature, but they all act by stimulating innate immune system of plants. So, plants can better fight pathogens. Furthermore, there are many similarities in pathogen perception systems and cellular signalling in plants and animals. It is well established that many elicitors stimulate both human and plant innate immunity (Zipfel and Felix, 2005). Therefore, it is likely that human innate immunity could be modulated by PDS. The aim of this study is to evaluate pro/anti-inflammatory activity of five different commercially available PDS on human c…

Protein S-nitrosylation: What's going on in plants?

International audience; Nitric oxide (NO) is now recognized as a key regulator of plant physiological processes. Understanding the mechanisms by which NO exerts its biological functions has been the subject of extensive research. Several components of the signaling pathways relaying NO effects in plants, including second messengers, protein kinases, phytohormones, and target genes, have been characterized. In addition, there is now compelling experimental evidence that NO partly operates through posttranslational modification of proteins, notably via S-nitrosylation and tyrosine nitration. Recently, proteome-wide scale analyses led to the identification of numerous protein candidates for S-…

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…

Early signaling events induced by elicitors of plant defenses

International audience; Plant pathogen attacks are perceived through pathogenissued compounds or plant-derived molecules that elicit defense reactions. Despite the large variety of elicitors, general schemes for cellular elicitor signaling leading to plant resistance can be drawn. In this article, we review early signaling events that happen after elicitor perception, including reversible protein phosphorylations, changes in the activities of plasma membrane proteins, variations in free calcium concentrations in cytosol and nucleus, and production of nitric oxide and active oxygen species. These events occur within the first minutes to a few hours after elicitor perception. One specific eli…

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…