Abstract
Colonisation of
Notholithocarpus densiflorus (Hook. and Arn.) Rehder tissues by
Phytophthora ramorum Werres, De Cock & Man in't Veld is not well understood. The pathogen is able to colonise nearly all tissues of this host but it is unclear how a tree is ultimately killed. In this research,
P. ramorum infected
N. densiflorus bark tissues were examined using various microscopic techniques to better understand the role of bark infection in killing a tree. Host responses to infection were detected by histological methods in conjunction with examining
P. ramorum colonisation. Results of this work indicate that the pathogen can colonise nearly all
N. densiflorus bark tissues but that phellogen and parenchyma of the inner bark are the most frequently and densely colonised. Pathogen specific elicitin labelling of
P. ramorum-infected
N. densiflorus sprouts caused hyphal cell walls to fluoresce in plant tissues, allowing specific identification of hyphae. Findings of this research show that nearly all bark tissues are capable of being colonised, that this host responds to infection with callose deposition, tissue discoloration, and cell collapse;; and that elicitins are present in cell walls of hyphae in infected bark tissues.
Keywords
histopathology,
immunofluorescence,
pathogenesis,
phloem,
sudden oak death,
tanoak.
Citation
Giesbrecht, Molly Botts; Hansen, Everett M.; Kitin, Peter. 2011. Histology of Phytophthora ramorum in Notholithocarpus densiflorus bark tissues. New Zealand Journal of Forestry Science. 41S: S89-S100. [published on-line: 25/10/2011]
