253 research outputs found
The main phytotoxic metabolite produced by a strain of Fusarium oxysporum inducing grapevine plant declining in Italy
No full textA strain of Fusarium oxysporum was isolated from grapevine showing heavy decline disease in a vineyard of Veneto region in Italy. The fungus showed to produce phytotoxic metabolites when grown in liquid culture. The main metabolite was identified as fusaric acid produced for the first time as a phytotoxin by a strain of F. oxysporom isolated from diseased grapevine plants. Its quantification in the fungus cultures filtrates was accomplished by HPLC. When tested on tobacco by leaf-puncture assay fusaric acid at 0.5 mg/mL induced the formation of extensive necrosis
Fungal Metabolites Antagonists towards Plant Pests and Human Pathogens: Structure-Activity Relationship Studies
No full textFungi are able to produce many bioactive secondary metabolites that belong to different classes of natural compounds. Some of these compounds have been selected for their antagonism against pests and human pathogens and structure–activity relationship (SAR) studies have been performed to better understand which structural features are essential for the biological activity. In some cases, these studies allowed for the obtaining of hemisynthetic derivatives with increased selectivity and stability in respect to the natural products as well as reduced toxicity in view of their potential practical applications. This review deals with the SAR studies performed on fungal metabolites with potential fungicidal, bactericidal, insecticidal, and herbicidal activities from 1990 to the present (beginning of 2018)
Quality principles for cultural Web sites: a Handbook
No full textprinted and on-line versions, co-author with Eelco Bruinsma, Christophe Dessaux, Ciaran Clissman, Jean-Pierre Dalbéra, David Dawson, Isabelle Dujacquier, Axel Ermert, Pierluigi Feliciati, Fedora Filippi, Muriel Foulonneau,
Antonella Fresa, Monika Hagedorn-Saupe, Annette Kelly, Brian Kelly, Daniel Malbert, Andrea Mulrenin, Stefan Rhode-Enslin, Marius Snyders, Gert Van Tittelboom, Frank von Hage
The Fungal Phytotoxin Lasiojasmonate A Activates the Plant Jasmonic Acid Pathway
No full textJasmonates are signaling compounds that regulate plant responses to stress. Jasmonic acid (JA) is the direct precursor of the bioactive plant hormone JA-Ile, the ligand of the COI1-JAZ co-receptor complex. JA, its methyl ester and three furanonyl esters were recently isolated from the grapevine pathogen Lasiodiplodia mediterannea sp. The JA ester lasiojasmonate A (LasA) is the first reported naturally occurring JA-furanone, whose mode of action is currently unexplored. Here we show that LasA activates many JA-regulated responses in planta, including protein degradation, gene expression, and physiological processes. These in vivo effects required LasA conversion into JA, formation of JA-Ile and its recognition by the plant JA-Ile perception complex. These data suggest a mode of action of the natural fungal LasA as an inactive JA pool that can be transformed into the bioactive JA-Ile form. We propose that fungal production of JA derivates such as LasA occur at late infection stages to induce plant JA responses such as cell death, and facilitate fungal infection
Advances on Fungal Phytotoxins and their Role in Grapevine Trunk Diseases
No full textGrapevines are produced worldwide with important impact on local economies. Several biotic stresses induce serious diseases of grapevine, which severly affect the quantity and the quality of production. One of the most important problems of vineyards worldwide is the high incidence of grapevine trunk diseases (GTD) induced by fungi belonging to several genera. Environmental-friendly methods for GTD control are being studied. This manuscript offers a perspective and an advanced overview on the fungal phytotoxins involved in GTD and their eventual role in the development of disease symptoms
Synthesis and mode of action studies of N-[(-)-jasmonyl]-S-tyrosin and ester seiridin jasmonate
No full textRecent analyses on fungal jasmonic acid (JA)-containing metabolites suggest a mode-of-action of these naturally occurring compounds as inactive storage pools of JA. Plants and/or fungi can catabolize JA into the bioactive jasmonyl-isoleucine (JA-Ile) that in turn activates the JA-Ile-pathway in planta. To extend our knowledge on JA-derivates related to natural occurring JA conjugates, N-[(-)-jasmonyl]-S-tyrosin (JATyr) and the ester JA-Sei between JA and seiridin, a fungal disubstituted furanone, were synthesized. The classical procedures for ester synthesis were applied for compound JA-Sei, while N-[(-)-jasmonyl]-Styrosin was synthesized with an optimized procedure. JA-Tyr and JA-Sei were characterized by spectroscopic method (essentially 1D and 2D NMR spectroscopy and ESI-MS) and their stereochemical composition was determined by means of HPLC and circular dichroism analysis. Finally, the activity of these JA-derivates was analyzed in planta. JA-Tyr and JA-Sei trigger JA-regulated plant responses, such as protein degradation and growth inhibition. These effects require the conversion of JA into JA-Ile and its recognition by the plant JA-Ile perception complex COI1-JAZ. Overall, these data suggest a mode-ofaction of JA-Tyr and JA-Sei as inactive pool of JA that can be transformed into the bioactive JA-Ile to induce the canonical JA-Ile-pathway
Melleins—Intriguing Natural Compounds
No full textMelleins are 3,4-dihydroisocoumarins mainly produced by fungi, but also by plants, insects and bacteria. These specialized metabolites play important roles in the life cycles of the producers and they are involved in many biochemical and ecological processes. This review outlines the isolation and chemical and biological characterizations of natural-occurring melleins from the first report of (R)-mellein in 1933 to the most recent advances in their characterization in 2019. In addition, the pathways that could be involved in mellein biosynthesis are discussed, along with the enzymes and genes involved
Involvement of phenazine-1-carboxylic acid in the interaction between Pseudomonas chlororaphis subsp. aureofaciens strain M71 and Seiridium cardinale in vivo
No full textPseudomonas chlororaphis subsp. aureofaciens encompasses bacterial strains that effectively control phytopathogenic fungi through the production of the natural antibiotics named phenazines. In this work, the involvement of phenazine production in the interaction between the biological control agent P. chlororaphis subsp. aureofaciens M71 and the fungus Seiridium cardinale, a serious cypress pathogen, was investigated. Field trials were carried out to assess the role of phenazines in the control of S. cardinale in vivo. Results showed that P. chlororaphis subsp. aureofaciens M71 and 30-84, both able to produce phenazine-1-carboxylic acid (PCA), drastically reduced the canker development incited by S. cardinale. Conversely, strain M71b, a natural gacA mutant of P. chlororaphis subsp. aureofaciens M71, showed a decrease in PCA production and a reduction in controlling S. cardinale. These results were enforced by the reduction of canker size higher than 94% registered when 6 μg of pure PCA was directly applied on each cypress wound. Furthermore, PCA was detected in cypress plant tissues only when P. chlororaphis subsp. aureofaciens M71 was interacting with S. cardinale for 30 days. All these data support that the biological control of S. cardinale achieved by the application of P. chlororaphis subsp. aureofaciens M71 relies mainly on the ability of the bacterial strain to produce PCA in planta
Isolation of Phytotoxic Phenols and Characterization of a New 5-Hydroxymethyl-2-isopropoxyphenol from Dothiorella vidmadera, a Causal Agent of Grapevine Trunk Disease
No full textPolyphenols were characterized from Dothiorella vidmadera (DAR78993), which was isolated from a grapevine in Australia. In total, six polyphenols were isolated including a new polyphenol characterized by a spectroscopic method (essentially NMR and HR ESIMS) as 5-hydroxymethyl-2-isopropoxyphenol. Tyrosol, benzene-1,2,4-triol, resorcinol, 3-(hydroxymethyl)phenol, and protocatechuic alcohol, the latter being the main metabolite, were also isolated. Although these are already known as naturally occurring compounds in microorganisms and plants, this is the first time they have been isolated from fungal organisms involved in grapevine trunk disease. When assayed on tomato seedlings, all the compounds show similar phytotoxic effects. However, when assayed on grapevine leaves (Vitis vinifera cv Shiraz), resorcinol was the most toxic compound, followed by protocatechuic alcohol and 5-hydroxymethyl-2-isopropoxyphenol
Spencertoxin and spencer acid, new phytotoxic derivatives of diacrylic acid and dipyridinbutan-1,4-diol produced by Spencermartinsia viticola , a causal agent of grapevine Botryosphaeria dieback in Australia
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