Isolation and partial characterization of antagonistic peptides produced by Paenibacillus sp. strain B2 isolated from the sorghum mycorrhizosphere.

ABSTRACT Paenibacillus sp. strain B2, isolated from the mycorrhizosphere of sorghum colonized by Glomus mosseae , produces an antagonistic factor. This factor has a broad spectrum of activity against gram-positive and gram-negative bacteria and also against fungi. The antagonistic factor was isolated from the bacterial culture medium and purified by cation-exchange, reverse-phase, and size exclusion chromatography. The purified factor could be separated into three active compounds following characterization by amino acid analysis and by combined reverse-phase chromatography and mass spectrometry (liquid chromatography-mass spectrometry and mass spectrometry-mass spectrometry). The first com…

.) Clone-dependent expression of grapevine esca disease.

International audience; The occurrence of grapevine trunk diseases (GTDs) increases gradually within vineyards, leading to important economic losses. Several factors could affect grapevine susceptibility to GTDs, especially climate, vine age, soil fertilization, and also rootstock, cultivar and clone. For a cultivar, the level of disease expression can vary with region and from year to year. In this context, our objective was to assess if the expression of esca disease, one of the most widespread GTDs, was also clone-dependent. Two clones (76 and 95) of the “Chardonnay” cultivar, grown in the same plot, were compared according to their developmental and physiological traits, metabolome, and…

Clone-Dependent Expression of Esca Disease Revealed by Leaf Metabolite Analysis

International audience; Grapevine trutk diseases, especially Esca, are of major concern since they gradually alter vineyards worldwide and cause heavy economic losses. The expression of Esca disease symptoms depends on several factors, including the grapevine cultivar. In this context, a possible clone-dependent expression of the Esca disease was studied. Two clones of 'Chardonnay' grown in the same plot were compared according to their developmental and physiological traits, metabolome, and foliar symptom expression. Analysis of their leaf metabolome highlighted differences related to symptom expression. Interestingly, the content of a few specific metabolites exhibited opposite variations…

L-Tyrosine beta-naphthylamide is a potent competitive inhibitor of tyramine N-(hydroxycinnamoyl)transferase in vitro

Expression clone-dépendante de l’Esca chez la vigne

National audience; L’incidence des maladies du bois de la vigne (MDB) augmente graduellement au sein des vignobles, causant d’importantes pertes économiques. Le coût mondial du remplacement de vignes malades est estimé à plus d’1,5 milliards de dollars par an [1]. En France, presque 13% du vignoble est affecté [2]. Plusieurs facteurs pourraient influencer la sensibilité aux MDB, notamment le climat, l’âge de la vigne, la fertilisation du sol, le porte-greffe ainsi que le cépage [3]. Actuellement, aucun cépage tolérant aux MDB n’a pu être identifié et le niveau de l’expression des MDB pour un cépage donné peut varier en fonction de la région et d’une année à l’autre [3], et probablement selo…

Characterization and purification of a bacterial chlorogenic acid esterase detected during the extraction of chlorogenic acid from arbuscular mycorrhizal tomato roots

International audience; A Gram-negative bacterium able to grow using chlorogenic acid (5-caffeoylquinic acid) as sole carbon source has been isolated from the roots of tomato plants inoculated with the arbuscular mycorrhizal fungus Rhizophagus irregularis. An intracellular esterase exhibiting very high affinity (K-m = 2 mu M) for chlorogenic acid has been extracted and purified by FPLC from the chlorogenate-grown cultures of this bacterium. The molecular mass of the purified esterase determined by SDS-PAGE was 61 kDa and its isoelectric point determined by chromatofocusing was 7.75. The esterase hydrolysed chlorogenic acid analogues (caffeoylshikimate, and the 4- and 3-caffeoylquinic acid i…

Bioprotection du pois par le champignon mycorhizogène à arbuscules Glomus mosseae vis-à-vis du champignon pathogène Aphanomyces euteiches

National audience

Dual mode of action of grape cane extracts against Botrytis cinerea

International audience; Crude extracts of Vitis vinifera canes represent a natural source of stilbene compounds with well characterized antifungals properties. In our trials, exogenous application of a stilbene extract (SE) obtained from grape canes on grapevine leaves reduces the necrotic lesions caused by Botrytis cinerea. The SE showed to possess a direct antifungal activity by inhibiting the mycelium growth. The activation of some grapevine defense mechanism was also investigated. H2O2 production and activation of mitogen-activated protein kinase (MAPK) phosphorylation cascades as well as accumulation of stilbenoid phytoalexins were explored on grapevine cell suspension. Moreover, the t…

Detection of an O-methyltransferase synthesising acetosyringone in methyl jasmonate-treated tobacco cell-suspensions cultures.

Acetosyringone (3',5'-dimethoxy-4'-hydroxyacetophenone) is a well-known and very effective inducer of the virulence genes of Agrobacterium tumefaciens but the precise pathway of its biosynthesis in plants is still unknown. We have used two tobacco cell lines, cultured in suspension and exhibiting different patterns of accumulation of acetosyringone in their culture medium upon treatment with methyl jasmonate, to study different steps of acetosyringone biosynthesis. In the two cell lines studied, treatment with 100 mu M methyl jasmonate triggered a rapid and transient increase in acetovanillone synthase activity followed by a progressive increase in S-adenosyl-L-methionine: 5-hydroxyacetovan…

Purification and partial amino acid sequencing of a mycorrhiza-related chitinase isoform from Glomus mosseae-inoculated roots of Pisum sativum L

International audience

Detection of a plant enzyme exhibiting chlorogenate-dependant caffeoyltransferase activity in methanolic extracts of arbuscular mycorrhizal tomato roots

When Glomus intraradices-colonised tomato roots were extracted in methanol at 6 degrees C, chlorogenic acid (5-caffeoylquinic acid), naturally present in the extract, was slowly converted by transesterification into methyl caffeate. The progress of the reaction could be monitored by HPLC. The reaction only occurred when the ground roots were left in contact with the hydro-alcoholic extract and required the presence of 15-35% water in the mixture. When the roots were extracted in ethanol, chlorogenic acid was transformed to ethyl caffeate in the same conditions. The reaction was also detected in Glomus mosseae-colonised tomato root extracts. It was also detectable in non-mycorrhizal root ext…

l-Tyrosine β-naphthylamide is a potent competitive inhibitor of tyramine N-(hydroxycinnamoyl)transferase in vitro

L-Tyrosine beta-naphthylamide, a synthetic substrate designed to measure tyrosine aminopeptidase activity, is a potent inhibitor of hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)transferase (THT) purified from elicited tobacco cell-suspension cultures. The inhibition is competitive, with the inhibitor binding reversibly to the tyramine binding site of the enzyme. Similar results were obtained with THT extracted from elicited potato cell-suspension cultures. Ki values were found to be 0.66 microM for the enzyme from tobacco and 0.3 microM for the enzyme from potato. L-Tyrosine 7-amido-4-methylcoumarin, a fluorogenic substrate for tyrosine aminopeptidases, the structure of which is close …

Stimulation of Defense Reactions in Medicago truncatula by Antagonistic Lipopeptides from Paenibacillus sp. Strain B2

ABSTRACT With the aim of obtaining new strategies to control plant diseases, we investigated the ability of antagonistic lipopolypeptides (paenimyxin) from Paenibacillus sp. strain B2 to elicit hydrogen peroxide (H 2 O 2 ) production and several defense-related genes in the model legume Medicago truncatula . For this purpose, M. truncatula cell suspensions were used and a pathosystem between M. truncatula and Fusarium acuminatum was established. In M. truncatula cell cultures, the induction of H 2 O 2 reached a maximum 20 min after elicitation with paenimyxin, whereas concentrations higher than 20 μM inhibited H 2 O 2 induction and this was correlated with a lethal effect. In plant roots in…