Changes in plant metabolism and accumulation of fungal metabolites in response to Esca proper and apoplexy expression in the whole grapevine

Trunk diseases have become among the most important grapevine diseases worldwide. They are caused by fungal pathogens that attack the permanent woody structure of the vines and cause various symptoms in woody and annual organs. This study examined modifications of plant responses in green stem, cordon and trunk of grapevines expressing Esca proper (E) or apoplexy (A) event, which are the most frequent grapevine trunk disease symptoms observed in Europe. Transcript expression of a set of plant defense- and stress-related genes was monitored by quantitative RT-PCR while plant phytoalexins and fungal metabolites were quantified by HPLC-MS in order to characterize the interaction between the grapevine and trunk disease agents. Expression of genes encoding enzymes of the phenylpropanoid pathway and trans-resveratrol content were altered in the three organs of diseased plants, especially in the young tissues of A plants. PR proteins and the antioxidant system were severely modulated in A plants, which indicates a drastic stress effect. In the meantime, fungal polyketides 6-MSA, (R)-mellein and (3R,4R)-4-hydroxymellein, were accumulated in A plants that suggests their potential effect on plant metabolism during the appearance of foliar symptoms

Reproducing Botryosphaeria dieback foliar symptoms in a simple model system

Botryosphaeria dieback is a grapevine trunk disease with a worldwide distribution and associated with Diplodia seriata and Neofusicoccum parvum among several other Botryosphaeriaceae species. The aforementioned xylem-inhabiting fungi cause wood lesions, leaf and berry symptoms and eventually lead to the death of the plant. The aim of this work was to develop a simple model system to reproduce the foliar symptoms caused by D. seriata and N. parvum to better characterize fungal pathogenicity and determine the mechanisms involved in symptom development. Green stems of grafted grapevine cuttings cv. Aragonez were inoculated with three isolates of N. parvum and two isolates of D. seriata with different degrees of virulence and the experiment was repeated four times from 2011 to 2014. Three months after inoculation, the lesions associated with N. parvum were larger than those associated with D. seriata. Similarly, eight months after inoculation the percentage of plants showing foliar symptoms was greater in the N. parvum treatments than in the D. seriata treatments. During the emergence of foliar symptoms, plant stress-related responses were modulated in green stems and leaves, especially a down-regulation of superoxide dismutase (SOD) and fasciclin-like arabinogalactan protein (fascAGP) and an up-regulation of stilbene synthase (STS) with an accumulation of phenolics. In conclusion, the simple model system developed allowed a good characterization of isolate pathogenicity and correlation with foliar symptoms of Botryosphaeria dieback, namely spots on leaf margin and blade

Phytotoxic metabolites from Neofusicoccum parvum, a pathogen of Botryosphaeria dieback of grapevine

Liquid chromatography-diode array screening of the organic extract of the cultures of 13 isolates of the fungus Neofusicoccum parvum, the main causal agent of botryosphaeria dieback of grapevine, showed similar metabolites. One strain was selected for further chemical studies and led to the isolation and characterisation of 13 metabolites. Structures were elucidated through spectroscopic analyses, including one- and two-dimensional NMR and mass spectrometry, and through comparison to literature data. The isolated compounds belong to four different chemical families: five metabolites, namely, ( )-terremutin (1), (+)-terremutin hydrate (2), (+)-epi-sphaeropsidone (3) ( )-4-chloro-terremutin hydrate (4) and(+)-4- hydroxysuccinate-terremutin hydrate (5), belong to the family of dihydrotoluquinones; two metabolites, namely, (6S,7R) asperlin (6) and (6R,7S)-dia-asperlin (7), belong to the family of epoxylactones; four metabolites, namely, (R)-( )-mellein (8), (3R,4R)-4-hydroxymellein (9), (3R,4S)-4-hydroxymellein (10) (R)( )-3-hydroxymellein (11), belong to the family of dihydroisocoumarins; and two of the metabolites, namely, 6-methyl-salicylic acid (12) and 2-hydroxypropyl salicylic acid (13), belong to the family of hydroxybenzoic acids. We determined the phytotoxic activity of the isolated metabolites through a leaf disc assay and the expression of defence-related genes in Vitis vinifera cells cv. Chardonnay cultured with ( )-terremutin (1), the most abundant metabolite. Finally, analysis of the brown stripes of grapevine wood from plants showing botryosphaeria dieback symptoms revealed the presence of two of the isolated phytotoxinsinfo:eu-repo/semantics/publishedVersio

Protection de la vigne contre Botrytis cinerea et stimulation des mécanismes de défense à l aide de bactéries issues du vignoble champenois

Le développement de nouvelles alternatives à la lutte chimique contre Botrytis cinerea chez la vigne, notamment par recours à l utilisation des bactéries issues du vignoble champenois fait l objet de cette thèse. Ces bactéries, isolées de la rhizosphère et de différents organes de vignes non contaminées, sont deux Acinetobacter lwoffii PTA-113 et PTA-152, une Bacillus subtilis PTA-271, deux Pantoea agglomerans PTA-AF1 et PTA-AF2 ainsi que deux Pseudomonas fluorescens PTA-268 et PTA-CT2. Les expériences réalisées de manière principale en conditions du vignoble, font apparaître que ces bactéries appliquées en souches pures ou en mélanges de souches sont capables d induire des réactions de défense chez la vigne matérialisées par une stimulation des activités de chitinase et b-1,3-glucanase dans les feuilles et les baies de vigne. Ces réactions typiques de défense sont variables selon la souche, les combinaisons de souches et leur mode d application, et sont pour la plupart associées à une protection des différents organes de la vigne contre Botrytis cinerea. Les souches les plus actives sont représentées par les A. lwoffi, P. fluorescens et P. agglomerans PTA-AF1 chez les feuilles et P. agglomerans PTA-AF1 et PTA-AF2 chez les baies. L association des deux P. agglomerans (AF1+AF2) ou encore P. agglomerans en présence de B. subtilis ou d A. lwoffi se traduit aussi par une protection significative contre B. cinerea, ne dépassant pas celle obtenue en présence des bactéries individuellesThe development of new alternatives to chemicals against Botrytis cinerea in grapevine, especially by using bacteria originated from Champagne vineyard is the objective of this thesis. These bacteria isolated from the rhizosphere and from different healthy grapevine organs, are two Acinetobacter lwoffii PTA-113 and PTA-152, a Bacillus subtilis PTA-271, two Pantoea agglomerans PTA-AF1 and PTA-AF2 and two Pseudomonas fluorescens PTA-268 and PTA-CT2. Experiments performed mainly in vineyard demonstrated that these bacteria applied individually or in combination are able to induce defence reactions in grapevine as evidenced by a stimulation of chitinase and b-1,3-glucanase activities in leaves and berries. The intensity of these defence reactions is dependent on bacterial strain, combination of bacteria and their application method. They are associated to an induced protection of both organs against Botrytis cinerea. The most active strains are A. lwoffi, P. fluorescens and P. agglomerans PTA-AF1 in leaves and P. agglomerans PTA-AF1 and PTA-AF2 in berries. The combination of two P. agglomerans (AF1+AF2) or P. agglomerans with B. subtilis or with A. lwoffi also lead to a significant protection against B. cinerea, which is not higher than that obtained with individual bacteriaREIMS-BU Sciences (514542101) / SudocSudocFranceF

Conception, characterization of physicochemical properties and biological activity against fungi and bacteria

International audienc

Investing the mode of action of resistance inducers during protection of wheat against powdery mildew

International audienc