1,721,039 research outputs found
Effects of three esca-associated fungi on Vitis vinifera L. I. Characterization of secondary metabolites in culture media and host responses to the pathogens in calli
No full textPhaeomoniella chlamydospora (Pch) and Togninia minima (Tmi) produced scytalone, isosclerone and pullulans in liquid cultures, as
well as in calli. Secondary metabolites and host defense compounds were shown to occur in calli of Vitis vinifera cv. Italia and cv. Matilde
infected by the esca-associated fungi Pch, Tmi and Fomitiporia mediterranea (Fme). Calli of both cvs. were grown as dual cultures with
Pch, Tmi and Fme. The fungi grew well in the presence of calli of both cvs., but callus growth was reduced. Accumulation and changes of
total phenolics and recurring phenolics, and of two phytotoxic pentaketides and pullulans were analyzed by HPLC. On comparing
results for cv. Italia and cv. Matilde, it can be seen that concentrations of phenolics are strongly related to the cv. The paper discusses the
possible relationship between melanin biosynthesis in Pch and Tmi, which utilize pentaketide metabolites as intermediates and their
pathogenicity related to phytotoxity of scytalone and isosclerone
Effects of three esca-associated fungi on Vitis vinifera L.: V. Changes in the chemical and biological profile of xylem sap from diseased cv. Sangiovese vines
No full textA vineyard of Vitis vinifera cv. Sangiovese was surveyed for incidence of esca and xylem sap collection. Sap samples were collected
from healthy vines and from those with dual infection by Phaeomoniella chlamydospora (Pch) and Togninia minima (Tmi) or triple
infection by Pch, Tmi and Fomitiporia mediterranea (Fme), during each early spring in a 3-year period (2001–2003). In order to analyse
the possible trends in the climatic data, temperature and rainfall were assessed. At sap harvesting, aliquots of sap were assayed for
phytotoxicity and extracted with ethyl acetate for phytotoxin recovery. Moreover, the exopolysaccharide (EPS) content was evaluated on
several sap samples during the bleeding period. Conidia of Pch and Tmi, mycelium of Fme and their secondary metabolites were found in
the sap of the esca-affected vines, indicating that the pathogens and their by-products together with some defence substances were
accumulated and then translocated. Bioactivity tests showed toxicity of the sap from esca-affected vines to healthy detached leaves of
cv. Sangiovese. The daily amount of sap, the pH, and the volume (Jv) and solute (Js) fluxes were analysed as a function of the infecting
fungi. Pullulan, glucogalactomannan(s) and arabinogalactan(s) are the main EPS in the esca-infected vines, whereas in the sap of healthy
vines no traces of pullulan were found. Scytalone and isosclerone usually produced in vitro by Pch and Tmi were also detected in the sap
of vines infected by Pch and Tmi or by Pch, Tmi and Fme. The endogenous phytohormone content of healthy vines evaluated by the
cutting bioassay was different from that of infected vines. Four phenolics belonging to three classes e.g., benzoic acid derivatives,
stilbenes and flavonol-glycosides were separated and identified by HPLC
Effetti dell'azoto inorganico e del carbonio organico sulla produzione di esopolisaccaridi in vitro e sulla morfologia di ceppi di Cryphonectria parasitica
No full textExtracellular Enzyme Localization During Inter- or Intraspecific Interactions of Fungi Associated with Esca of Grapevine
No full text
Effect of Phaeoacremonium aleophilum, Phaeomoniella chlamydospora and Fomitiporia mediterranea on accumulation and changes of polyphenols and phytotoxins in grapevine calli and in planta
No full textEsca-associated fungi and grapevine response: induction of host defence substances and their degradation by the pathogens
No full textProduction of pullulans by virulent and hypovirulent strains of Cryphonectria parasitica
No full textEffects of three esca-associated fungi on Vitis vinifera L. II. Characterization of biomolecules in xylem sap and leaves of healthy and diseased vines
No full textSecondary metabolites and host defense compounds were shown to occur in xylem sap, and leaves of Vitis vinifera cv. Italia and cv.
Matilde naturally infected by the esca-associated fungi Phaeomoniella chlamydospora (Pch), Togninia minima (Tmi) and Fomitiporia
mediterranea (Fme). Samples of xylem sap and leaves were collected from healthy vines and from vines showing severe symptoms of
brown wood-streaking caused by Pch and Tmi, or from vines with symptoms of both brown wood-streaking and white rot caused by
Fme. Xylem sap collection was carried out during the early spring of 2003 and 2004, corresponding to the phenological phases: (A)
cotton bud; (B) green tip; (C) leaves out; (D) stretched out leaves; and (E) visible clusters. In the present work we have studied the
accumulation of biomolecules (pentaketides and a-glucans), host defense compounds (benzaldehydes, benzoic acid and cinnamic acid
derivatives, flavonols, flavanols, flavan-3-ol derivatives and stilbenes) at different stages of grapevine development. Accumulation and
changes in total phenolics and recurring phenolics, and of three phytotoxic secondary metabolites (scytalone, isosclerone and pullulan)
were analyzed by HPLC. On comparing results for cv. Italia and cv. Matilde, it can be seen that phenolic concentrations are strongly
related to the c
Effect of esca-associated fungi on white and red grapevine cultivars
No full textTogninia minima (Tmi), Phaeomoniella chlamydospora (Pch) and/or Fomitiporia mediterranea (Fme) are three well known esca-associated fungi. We compared two cultivars of Vitis vinifera, ‘Italia’ and ‘Sangiovese’ differing in susceptibility to these fungi. Scytalone, isosclerone, pullulan, and enzymes (laccase, tannase, peroxidase) produced by the pathogens, and host defence compounds (phenolics) were used for the comparison. The fungal metabolites were found in bioactive concentrations in leaves, rachises and berries of esca-affected vines at various stages of growth. The findings suggest that at least a part of esca foliar and fruit symptoms are caused by toxic fungal metabolites originating in the infected tissues and translocated to the crown via the xylem stream. Absorption of weak solutions of the fungal metabolites by sound leaves and berries of both cvs. induced esca-like symptoms. The presence of laccase, tannase and phenoloxidase in infected tissues aided symptom development. The concentration of constitutive or inducible phenolics in both cvs. varied in relation to phenological phases. Values of almost all the parameters measured in this study indicated that grapevines infected with Tmi and Pch gave a different response than vines infected by Tmi, Pch and Fme. These results indicate that infection by all three fungi gives rise to a range of biochemical and physiological events leading to the full scale of esca symptoms
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