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Increase in ring width, vessel number and δ18O in olive trees infected with Xylella fastidiosa.

  • Sabella, Erika1
  • Moretti, Samuele2, 3
  • Gärtner, Holger2
  • Luvisi, Andrea1
  • De Bellis, Luigi1
  • Vergine, Marzia1
  • Saurer, Matthias2
  • Cherubini, Paolo2, 4
  • 1 Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, Lecce, 73100, Italy. , (Italy)
  • 2 WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland. , (Switzerland)
  • 3 Laboratoire Vigne, Biotechnologies et Environnement (LVBE, EA 3991), Université de Haute-Alsace, 33 rue de Herrlisheim, 68008 Colmar Cedex, France. , (France)
  • 4 Department of Forest and Conservation Sciences, University of British Columbia, 3041 - 2424 Main Mall, Vancouver, BC, Canada. , (Canada)
Published Article
Tree Physiology
Oxford University Press
Publication Date
Oct 29, 2020
DOI: 10.1093/treephys/tpaa095
PMID: 32705131


Xylella fastidiosa (Xf) Wells, Raju et al., 1986 is a bacterium that causes plant diseases in the Americas. In Europe, it was first detected on the Salento Peninsula (Italy), where it was found to be associated with the olive quick decline syndrome. Here, we present the results of the first tree-ring study of infected and uninfected olive trees (Olea europaea L.) of two different cultivars, one resistant and one susceptible, to establish the effects induced by the spread of the pathogen inside the tree. Changes in wood anatomical characteristics, such as an increase in the number of vessels and in ring width, were observed in the infected plants of both the cultivars Cellina di Nardò (susceptible to Xf infection) and Leccino (resistant to Xf infection). Thus, whether infection affects the mortality of the tree or not, the tree shows a reaction to it. The presence of occlusions was detected in the wood of both 4-year-old branches and the tree stem core. As expected, the percentage of occluded vessels in the Xf-susceptible cultivar Cellina di Nardò was significantly higher than in the Xf-resistant cultivar Leccino. The δ 18O of the 4-year-old branches was significantly higher in infected trees of both cultivars than in noninfected trees, while no variations in δ 13C were observed. This suggests a reduction in leaf transpiration rates during infection and seems to be related to the occlusions observed in rings of the 4-year-old branches. Such occlusions can determine effects at leaf level that could influence stomatal activity. On the other hand, the significant increase in the number of vessels in infected trees could be related to the tree's attempt to enhance water conductivity in response to the pathogen-induced vessel occlusions. © The Author(s) 2020. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: [email protected]

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