Skip Navigation



JXB Advance Access published online on May 17, 2008
Journal of Experimental Botany, doi:10.1093/jxb/ern124
This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrowOA All Versions of this Article:
59/10/2649    most recent
ern124v1
Right arrow E-letters: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when E-letters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Disclaimer
Google Scholar
Right arrow Articles by McElrone, A. J.
Right arrow Articles by Habdas, P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by McElrone, A. J.
Right arrow Articles by Habdas, P.
Agricola
Right arrow Articles by McElrone, A. J.
Right arrow Articles by Habdas, P.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© 2008 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details)

RESEARCH PAPER

Hydraulic disruption and passive migration by a bacterial pathogen in oak tree xylem

Andrew J. McElrone1,*, Susan Jackson2 and Piotr Habdas3

1USDA-ARS Crops Pathology and Genetics Research Unit, University of California, Davis, CA 95616, USA
2Department of Biology, Saint Joseph's University, Philadelphia, PA 19131, USA
3Department of Physics, Saint Joseph's University, Philadelphia, PA 19131, USA

* To whom correspondence should be addressed. E-mail: ajmcelrone{at}ucdavis.edu

Xylella fastidiosa (Xf) is a xylem-limited bacterial pathogen that causes leaf scorch symptoms in numerous plant species in urban, agricultural, and natural ecosystems worldwide. The exact mechanism of hydraulic disruption and systemic colonization of xylem by Xf remains elusive across all host plants. To understand both processes better, the functional and structural characteristics of xylem in different organs of both healthy and Xf-infected trees of several Quercus species were studied. Hydraulic conductivity (Ks) in Xf-infected petioles of Q. palustris and Q. rubra decreased significantly compared with healthy trees as the season progressed and plummeted to zero with the onset of scorch symptoms. Prior to the onset of symptoms, embolism was as much as 3.7 times higher in Xf-infected petioles compared with healthy controls and preceded significant reductions in Ks. Embolism likely resulted from pit membrane degradation during colonization of new petiole xylem and triggered the process that eventually led to vessel occlusion. Pit membrane porosity was studied using the following four methods to determine if a pathway exists in the xylem network of woody stems that allows for passive Xf migration: (i) calculations based on vulnerability to cavitation data, (ii) scanning electron micrographs, (iii) microsphere injections, and (iv) air seeding thresholds on individual vessels. All four methods consistently demonstrated that large pit membrane pores (i.e. greater than the diameter of individual Xf) occur frequently throughout the secondary stem xylem in several Quercus species. These large pores probably facilitate systemic colonization of the secondary xylem network and contribute to the high susceptibility to bacterial leaf scorch exhibited among these species.

Key words: Cavitation, embolism, hydraulic conductivity, vascular pathogens, Xylella fastidiosa, xylem-limited bacteria

Received 18 December 2007; Revised 4 April 2008 Accepted 7 April 2008


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Am. J. Enol. Vitic.Home page
G. A. Gambetta, T. L. Rost, and M. A. Matthews
Passive Pathogen Movement via Open Xylem Conduits in Grapevine Graft Unions
Am. J. Enol. Vitic., June 1, 2009; 60(2): 241 - 245.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.