Title: Pinus nigra–Sphaeropsis sapinea as a model pathosystem to investigate local and systemic effects of fungal infection of pines
Abstract: The Austrian pine/Sphaeropsis sapinea pathosystem was tested as a model to study the secondary metabolism of both localized and systemically induced defense responses in pine. Compared to wounding alone, fungal inoculations in lower stems of five-year-old potted Austrian pines induced significant (P<0.01) depletion or accumulation (0.4–101-fold) in reaction zone phloem of several soluble and cell-wall-bound phenolics, and a 1.8-fold increase in lignin deposition. Inoculations also resulted in significant (P<0.05) accumulation (up to 3-fold) of several compounds in the phloem 25 cm above the inoculation site, indicating systemic induction of metabolic pathways. Taxifolin was among the induced metabolites, but was only observed in lower stems, irrespective of treatment. Another putative flavonoid was observed only when trees were inoculated with live mycelia, suggesting a phytoalexin-like role for this compound. In spite of these changes, lignin content and concentrations of several metabolites considered important in resistance (such as stilbenes) were either not correlated, or were positively correlated, with lesion size. Only three metabolites had negative correlations with lesion size, suggesting a potential role in resistance. Protein and lipid fractions of mycelial extracts, as well as killed mycelium of the pathogen, were also examined as potential elicitors. Among the treatments other than live inoculation, killed mycelium was the strongest inducer of host responses, followed by the protein extract. Lipids did not elicit host responses different from wounding alone.
Publication Year: 2003
Publication Date: 2003-11-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 156
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