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Transcript profiling of the Heterobasidion-conifer pathosystem

host and pathogen responses to biotic stress

Adomas, Aleksandra (2007). Transcript profiling of the Heterobasidion-conifer pathosystem. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:35
ISBN 978-91-576-7334-3
[Doctoral thesis]

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Host–pathogen interactions have been studied mostly in agricultural crops, with very little work done in forest trees, particularly gymnosperms. The biology and genetics of one of the most economically important conifer pathogens Heterobasidion annosum sensu lato has been studied but knowledge about mechanisms of defence responses and resistance remains largely unexplored. A major set back for this conifer pathosystem is the lack of a suitable model system. In this thesis, a transcriptomic approach was used to analyse responses of pine seedling roots to H. annosum infection. The microarray profiling of Pinus sylvestris L. responses to infection with H. annosum revealed multiple overlapping strategies employed for defence purposes. Production of pathogenesis-related enzymes and antimicrobial proteins was supplemented by a major shift in primary and secondary metabolism. As there are no avirulent strains of H. annosum, a follow-up microarray study used Laccaria bicolor (an ectomycorrhizal symbiont) and Trichoderma aureoviride (a saprotroph) as non-pathogen models to determine whether the observed pine responses to H. annosum attack were specific. The results indicated that pine was able to recognize all three fungi and specifically distinguish whether they were pathogenic, neutral or beneficial microorganisms. An additional transcript profiling study investigated whether the documented responses to H. annosum infection were organ specific. Comparison of transcript profiles of pine needles and roots challenged with root (H. annosum) and shoot specific (Gremmeniella abietina) pathogens, indicated that the responses were more organ-specific than pathogen-specific. Finally, in parallel to the above studies and in the absence of any host genotype in the Pinaceae with total resistance against H. annosum, a molecular analysis of the mechanisms underlying the action of commonly used biocontrol agent, Phlebiopsis gigantea was conducted. Analysis of genes differentially expressed during the interaction of these two fungi revealed up-regulation of several P. gigantea genes vital for nutrient acquisition which may partly explain the observed competitive advantage over H. annosum. The results of this thesis have provided further insights into the molecular basis for specificity and recognition in conifer defence and the knowledge obtained from the fungal interaction study was considered a first step towards improving the efficacy of the biological control of H. annosum.

Authors/Creators:Adomas, Aleksandra
Title:Transcript profiling of the Heterobasidion-conifer pathosystem
Subtitle:host and pathogen responses to biotic stress
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2007
Number of Pages:42
ALLI. Asiegbu F.O., Adomas A. & Stenlid J. 2005. Conifer root and butt rot caused by Heterobasidion annosum (Fr.) Bref. sensu lato. Molecular Plant Pathology 6, 395-409. II. Adomas A., Heller G., Li G., Olson Å., Chu T.-M., Osborne J., Craig D., van Zyl L., Wolfinger R., Sederoff R., Dean R.A., Stenlid J., Finlay R. & Asiegbu F.O. 2007. Transcript profiling of conifer pathosystem: response of Pinus sylvestris root tissues to pathogen (Heterobasidion annosum) invasion. Tree Physiology, in press. III. Adomas A., Heller G., Olson Å., Osborne J., Karlsson M., Nahalkova J., van Zyl L., Sederoff R, Stenlid J., Finlay R., Asiegbu F.O. Comparative analysis of transcript abundance in Pinus sylvestris roots after challenge with a pathogenic, saprotrophic or mutualistic fungus. Submitted manuscript. IV. Adomas A. & Asiegbu F.O. Analysis of organ specific responses of Pinus sylvestris to shoot (Gremmeniella abietina) and root (Heterobasidion annosum) pathogens. Submitted manuscript. V. Adomas A., Eklund M., Johansson M. & Asiegbu F.O. (2006) Identification and analysis of differentially expressed cDNAs during nonself-competitive interaction between Phlebiopsis gigantea and Heterobasidion parviporum. FEMS Microbiology Ecology 57, 26–39. Paper IV has been accepted for publication in Molecular and Physiological Plant Pathology after the thesis was printed.
Place of Publication:Uppsala
ISBN for printed version:978-91-576-7334-3
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:pinus sylvestris, forest trees, heterobasidion annosum, host pathogen relations, defence mechanisms, laccaria, trichoderma, godronia, rots, genetic resistance, transcription, biological control, mycorrhizae, seedlings, roots
Keywords:Heterobasidion annosum, Pinus sylvestris, defence, microarray, transcript profiling, necrotroph, saprotroph, ectomycorrhiza, biocontrol, Phlebiopsis gigantea
Permanent URL:
ID Code:1365
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: Aleksandra Adomas
Deposited On:27 Mar 2007 00:00
Metadata Last Modified:02 Dec 2014 10:11

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