Time filter

Source Type

Barka E.A.,CNRS Research Unit on Grapevine and Wines in Champagne | Vatsa P.,CNRS Research Unit on Grapevine and Wines in Champagne | Sanchez L.,CNRS Research Unit on Grapevine and Wines in Champagne | Gaveau-Vaillant N.,CNRS Research Unit on Grapevine and Wines in Champagne | And 5 more authors.
Microbiology and Molecular Biology Reviews | Year: 2016

Actinobacteria are Gram-positive bacteria with high G+C DNA content that constitute one of the largest bacterial phyla, and they are ubiquitously distributed in both aquatic and terrestrial ecosystems. Many Actinobacteria have a mycelial lifestyle and undergo complex morphological differentiation. They also have an extensive secondary metabolism and produce about two-thirds of all naturally derived antibiotics in current clinical use, as well as many anticancer, anthelmintic, and antifungal compounds. Consequently, these bacteria are of major importance for biotechnology, medicine, and agriculture. Actinobacteria play diverse roles in their associations with various higher organisms, since their members have adopted different lifestyles, and the phylum includes pathogens (notably, species of Corynebacterium, Mycobacterium, Nocardia, Propionibacterium, and Tropheryma), soil inhabitants (e.g., Micromonospora and Streptomyces species), plant commensals (e.g., Frankia spp.), and gastrointestinal commensals (Bifidobacterium spp.). Actinobacteria also play an important role as symbionts and as pathogens in plant-associated microbial communities. This review presents an update on the biology of this important bacterial phylum. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Seifi H.S.,Ghent University | Curvers K.,Ghent University | De Vleesschauwer D.,Ghent University | Delaere I.,Ghent University | And 2 more authors.
New Phytologist | Year: 2013

Deficiency of abscisic acid (ABA) in the sitiens mutant of tomato (Solanum lycopersicum) culminates in increased resistance to Botrytis cinerea through a rapid epidermal hypersensitive response (HR) and associated phenylpropanoid pathway-derived cell wall fortifications. This study focused on understanding the role of primary carbon : nitrogen (C : N) metabolism in the resistance response of sitiens to B. cinerea. How alterations in C : N metabolism are linked with the HR-mediated epidermal arrest of the pathogen has been also investigated. Temporal alterations in the γ-aminobutyric acid (GABA) shunt, glutamine synthetase/glutamate synthase (GS/GOGAT) cycle and phenylpropanoid pathway were transcriptionally, enzymatically and metabolically monitored in both wild-type and sitiens plants. Virus-induced gene silencing, microscopic analyses and pharmacological assays were used to further confirm the data. Our results on the sitiens-B. cinerea interaction favor a model in which cell viability in the cells surrounding the invaded tissue is maintained by a constant replenishment of the tricarboxylic acid (TCA) cycle through overactivation of the GS/GOGAT cycle and the GABA shunt, resulting in resistance through both tightly controlling the defense-associated HR and slowing down the pathogen-induced senescence. Collectively, this study shows that maintaining cell viability via alterations in host C : N metabolism plays a vital role in the resistance response against necrotrophic pathogens. © 2013 New Phytologist Trust.

Trda L.,CNRS Agroecology Lab | Fernandez O.,CNRS Research Unit on Grapevine and Wines in Champagne | Boutrot F.,Norwich Research Park | Heloir M.-C.,CNRS Agroecology Lab | And 7 more authors.
New Phytologist | Year: 2014

The role of flagellin perception in the context of plant beneficial bacteria still remains unclear. Here, we characterized the flagellin sensing system flg22-FLAGELLIN SENSING 2 (FLS2) in grapevine, and analyzed the flagellin perception in the interaction with the endophytic plant growth-promoting rhizobacterium (PGPR) Burkholderia phytofirmans. The functionality of the grapevine FLS2 receptor, VvFLS2, was demonstrated by complementation assays in the Arabidopsis thaliana fls2 mutant, which restored flg22-induced H2O2 production and growth inhibition. Using synthetic flg22 peptides from different bacterial origins, we compared recognition specificities between VvFLS2 and AtFLS2. In grapevine, flg22-triggered immune responses are conserved and led to partial resistance against Botrytis cinerea. Unlike flg22 peptides derived from Pseudomonas aeruginosa or Xanthomonas campestris, flg22 peptide derived from B. phytofirmans triggered only a small oxidative burst, weak and transient defense gene induction and no growth inhibition in grapevine. Although, in Arabidopsis, all the flg22 epitopes exhibited similar biological activities, the expression of VvFLS2 into the fls2 background conferred differential flg22 responses characteristic for grapevine. These results demonstrate that VvFLS2 differentially recognizes flg22 from different bacteria, and suggest that flagellin from the beneficial PGPR B. phytofirmans has evolved to evade this grapevine immune recognition system. © 2013 New Phytologist Trust.

Fernandez O.,CNRS Research Unit on Grapevine and Wines in Champagne | Bethencourt L.,University of Picardie Jules Verne | Quero A.,University of Picardie Jules Verne | Sangwan R.S.,University of Picardie Jules Verne | Clement Christophe C.,CNRS Research Unit on Grapevine and Wines in Champagne
Trends in Plant Science | Year: 2010

The disaccharide trehalose is involved in stress response in many organisms. However, in plants, its precise role remains unclear, although some data indicate that trehalose has a protective role during abiotic stresses. By contrast, some trehalose metabolism mutants exhibit growth aberrations, revealing potential negative effects on plant physiology. Contradictory effects also appear under biotic stress conditions. Specifically, trehalose is essential for the infectivity of several pathogens but at the same time elicits plant defense. Here, we argue that trehalose should not be regarded only as a protective sugar but rather like a double-faced molecule and that further investigation is required to elucidate its exact role in stress tolerance in plants. © 2010.

Fernandez O.,CNRS Research Unit on Grapevine and Wines in Champagne | Theocharis A.,CNRS Research Unit on Grapevine and Wines in Champagne | Bordiec S.,CNRS Research Unit on Grapevine and Wines in Champagne | Feil R.,Max Planck Institute of Molecular Plant Physiology | And 4 more authors.
Molecular Plant-Microbe Interactions | Year: 2012

Low temperatures damage many temperate crops, including grapevine, which, when exposed to chilling, can be affected by symptoms ranging from reduced yield up to complete infertility. We have previously demonstrated that Burkholderia phytofirmans PsJN, a plant growth-promoting rhizobacteria (PGPR) that colonizes grapevine, is able to reduce chilling-induced damage. We hypothesized that the induced tolerance may be explained at least partly by the impact of bacteria on grapevine photosynthesis or carbohydrate metabolism during cold acclimation. To investigate this hypothesis, we monitored herein the fluctuations of photosynthesis parameters (net photosynthesis [P n], intercellular CO 2 concentration, stomatal conductances, ΦPSII, and total chlorophyll concentration), starch, soluble sugars (glucose, fructose, saccharose, mannose, raffinose, and maltose), and their precursors during 5 days of chilling exposure (4°C) on grapevine plantlets. Bacterization affects photosynthesis in a non-Vstomatal dependent pattern and reduced long-term impact of chilling on P n. Furthermore, all studied carbohydrates known to be involved in cold stress tolerance accumulate in nonchilled bacterized plantlets, although some of them remained more concentrated in the latter after chilling exposure. Overall, our results suggest that modification of carbohydrate metabolism in bacterized grapevine plantlets may be one of the major effects by which this PGPR reduces chilling-induced damage. © 2012 The American Phytopathological Society.

Sawicki M.,CNRS Research Unit on Grapevine and Wines in Champagne | Ait Barka E.,CNRS Research Unit on Grapevine and Wines in Champagne | Clement C.,CNRS Research Unit on Grapevine and Wines in Champagne | Vaillant-Gaveau N.,CNRS Research Unit on Grapevine and Wines in Champagne | Jacquard C.,CNRS Research Unit on Grapevine and Wines in Champagne
Journal of Experimental Botany | Year: 2015

In plants, flowering is a crucial process for reproductive success and continuity of the species through time. Fruit production requires the perfect development of reproductive structures. Abscission, a natural process, can occur to facilitate shedding of no longer needed, infected, or damaged organs. If stress occurs during flower development, abscission can intervene at flower level, leading to reduced yield. Flower abscission is a highly regulated developmental process simultaneously influenced and activated in response to exogenous (changing environmental conditions, interactions with microorganisms) and endogenous (physiological modifications) stimuli. During climate change, plant communities will be more susceptible to environmental stresses, leading to increased flower and fruit abscission, and consequently a decrease in fruit yield. Understanding the impacts of stress on the reproductive phase is therefore critical for managing future agricultural productivity. Here, current knowledge on flower/fruit abscission is summarized by focusing specifically on effects of environmental stresses leading to this process in woody plants. Many of these stresses impair hormonal balance and/or carbohydrate metabolism, but the exact mechanisms are far from completely known. Hormones are the abscission effectors and the auxin/ethylene balance is of particular importance. The carbohydrate pathway is the result of complex regulatory processes involving the balance between photosynthesis and mobilization of reserves. Hormones and carbohydrates together participate in complex signal transduction systems, especially in response to stress. The available data are discussed in relation to reproductive organ development and the process of abscission. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Theocharis A.,CNRS Research Unit on Grapevine and Wines in Champagne | Bordiec S.,CNRS Research Unit on Grapevine and Wines in Champagne | Fernandez O.,CNRS Research Unit on Grapevine and Wines in Champagne | Paquis S.,CNRS Research Unit on Grapevine and Wines in Champagne | And 4 more authors.
Molecular Plant-Microbe Interactions | Year: 2012

Several endophytic bacteria reportedly induce resistance to biotic stress and abiotic stress tolerance in several plant species. Burkholderia phytofirmans PsJN is a plant-growthpromoting rhizobacterium (PGPR) that is able to colonize grapevine tissues and induce resistance to gray mold. Further, PsJN induces physiological changes that increase grapevine tolerance to low nonfreezing temperatures. To better understand how bacteria induced the observed phenomena, stress-related gene expression and metabolite accumulation were monitored in 6-week-old Chardonnay grapevine plantlets after exposure to low nonfreezing temperatures. Under normal conditions (26°C), plantlet bacterization had no significant effect on the monitored parameters. By contrast, at 4°C, both stress-related gene transcripts and metabolite levels increased earlier and faster, and reached higher levels in PsJN-bacterized plantlets than in nonbacterized counterparts, in accordance with priming phenomena. The recorded changes may be correlated with the tolerance to cold stress conferred by the presence of PsJN. This is the first time that PGPR-induced priming has been shown to protect plants against low-temperature stress. Moreover, 1 week after cold exposure, levels of stress-related metabolites had declined more in PsJN-bacterized plants, suggesting that the endophyte is involved in the cold acclimation process via the scavenging system. © 2012 The American Phytopathological Society.

Hatmi S.,CNRS Research Unit on Grapevine and Wines in Champagne | Trotel-Aziz P.,CNRS Research Unit on Grapevine and Wines in Champagne | Villaume S.,CNRS Research Unit on Grapevine and Wines in Champagne | Couderchet M.,CNRS Research Unit on Grapevine and Wines in Champagne | And 2 more authors.
Journal of Experimental Botany | Year: 2014

Abiotic factors inducing osmotic stress can influence the plant immune response and resistance to pathogen infections. In this study, the effect of polyethylene glycol (PEG)-and sucrose-induced osmotic stress on polyamine (PA) homeostasis and the basal immune response in grapevine plantlets before and after Botrytis cinerea infection was determined. Pharmacological approaches were also addressed to assess the contribution of osmotic stress-induced PA oxidation to the regulation of defence responses and the susceptibility of grapevine to B. cinerea. Following osmotic stress or pathogen infection, PA homeostasis was linked to enhanced activity of diamine oxidases (CuAO) and PA oxidases (PAO) and the production of 1,3-diaminopropane. These responses paralleled the accumulation of the main stilbenic phytoalexins, resveratrol and ε-viniferin and upregulation of gene transcripts including STS (a stilbene synthase), PR-2 (a β-1,3-glucanase), PR3-4c (acidic chitinase IV), and PR-5 (a thaumatin-like protein), as well as NCED2 involved in abscisic acid biosynthesis. It was also demonstrated that leaves pre-exposed to osmotic stress and later inoculated with B. cinerea showed enhanced PA accumulation and attenuation of CuAO and PAO activities. This was consistent with the impaired production of phytoalexins and transcript levels of defence-and stress-related genes following infection, and the enhanced susceptibility to B. cinerea. Pharmacological experiments revealed that, under osmotic stress conditions, CuAO and PAO were involved in PA homeostasis and in the regulation of defence responses. Specific inhibition of CuAO and PAO in osmotically stressed leaves strongly attenuated the induction of defence responses triggered by B. cinerea infection and enhanced susceptibility to the pathogen. Taken together, this study reveals a contribution of PA catabolism to the resistance state through modulation of immune response in grapevine following osmotic stress and/or after B. cinerea infection. © 2013 The Author.

Delaunois B.,CNRS Research Unit on Grapevine and Wines in Champagne | Farace G.,CNRS Research Unit on Grapevine and Wines in Champagne | Jeandet P.,CNRS Research Unit on Grapevine and Wines in Champagne | Clement C.,CNRS Research Unit on Grapevine and Wines in Champagne | And 3 more authors.
Environmental Science and Pollution Research | Year: 2014

Development and optimisation of alternative strategies to reduce the use of classic chemical inputs for protection against diseases in vineyard is becoming a necessity. Among these strategies, one of the most promising consists in the stimulation and/or potentiation of the grapevine defence responses by the means of elicitors. Elicitors are highly diverse molecules both in nature and origins. This review aims at providing an overview of the current knowledge on these molecules and will highlight their potential efficacy from the laboratory in controlled conditions to vineyards. Recent findings and concepts (especially on plant innate immunity) and the new terminology (microbe-associated molecular patterns, effectors, etc.) are also discussed in this context. Other objectives of this review are to highlight the difficulty of transferring elicitors use and results from the controlled conditions to the vineyard, to determine their practical and effective use in viticulture and to propose ideas for improving their efficacy in non-controlled conditions. © 2013 Springer-Verlag Berlin Heidelberg.

Jeandet P.,CNRS Research Unit on Grapevine and Wines in Champagne | Clement C.,CNRS Research Unit on Grapevine and Wines in Champagne | Courot E.,CNRS Research Unit on Grapevine and Wines in Champagne | Cordelier S.,CNRS Research Unit on Grapevine and Wines in Champagne
International Journal of Molecular Sciences | Year: 2013

Phytoalexins are antimicrobial substances of low molecular weight produced by plants in response to infection or stress, which form part of their active defense mechanisms. Starting in the 1950's, research on phytoalexins has begun with biochemistry and bio-organic chemistry, resulting in the determination of their structure, their biological activity as well as mechanisms of their synthesis and their catabolism by microorganisms. Elucidation of the biosynthesis of numerous phytoalexins has permitted the use of molecular biology tools for the exploration of the genes encoding enzymes of their synthesis pathways and their regulators. Genetic manipulation of phytoalexins has been investigated to increase the disease resistance of plants. The first example of a disease resistance resulting from foreign phytoalexin expression in a novel plant has concerned a phytoalexin from grapevine which was transferred to tobacco. Transformations were then operated to investigate the potential of other phytoalexin biosynthetic genes to confer resistance to pathogens. Unexpectedly, engineering phytoalexins for disease resistance in plants seem to have been limited to exploiting only a few phytoalexin biosynthetic genes, especially those encoding stilbenes and some isoflavonoids. Research has rather focused on indirect approaches which allow modulation of the accumulation of phytoalexin employing transcriptional regulators or components of upstream regulatory pathways. Genetic approaches using gain-or less-of functions in phytoalexin engineering together with modulation of phytoalexin accumulation through molecular engineering of plant hormones and defense-related marker and elicitor genes have been reviewed. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Loading CNRS Research Unit on Grapevine and Wines in Champagne collaborators
Loading CNRS Research Unit on Grapevine and Wines in Champagne collaborators