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Understanding virulence of Heterobasidion annosum s.l., a root rot pathogen of conifers

Hu, Yang (2015). Understanding virulence of Heterobasidion annosum s.l., a root rot pathogen of conifers. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2015:118
ISBN 978-91-576-8434-9
eISBN 978-91-576-8435-6
[Doctoral thesis]

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Heterobasidion annosum sensu lato (s.l.) species are destructive pathogens causing root and butt rot in conifers. The species complex consists of five species: H. annosum sensu stricto (s.s.), H. abietinum, H. parviporum, H. irregulare and H. occidentale. The aim of this thesis was to improve the understanding of fungal virulence in this species complex. The comparison of H. irregulare and H. occidentale transcriptomes revealed differences in the consistently significant up-regulated genes (CUGs) in Norway spruce (Picea abies) bark. It appears that more CUGs involved in detoxification and in the production of secondary metabolites are activated in H. irregulare. By contrast, H. occidentale emphasizes carbohydrate degradation. This enrichment of CUGs in particular gene ontology terms may be driven by their host preferences and by their evolutionary history.

In H. irregulare, an endo-rhamnogalacturonase gene (HIRHG) from a virulence QTL was up-regulated during infection and the protein was mainly produced during growth on complex carbon sources. Although the HIRHG gene had been lost in most of the biotrophic and hemibiotrophic plant pathogens investigated, it was common in the necrotrophic pathogens and saprotrophs. Expression of HIRHG in Magnaporthe oryzae increased its capacity to grow on pectin, but did not significantly affect its virulence in our experimental set up.

In parallel, the evolution of RNA interference (RNAi) was investigated to lay a foundation for the establishment of reverse genetics study tools. Dicer and argonaute are central to the functioning of the RNAi machinery required for gene silencing applications. The evolution of argonaute- and dicer-encoding genes in 43 fungal genomes indicated an ancient duplication of dicer and argonaute genes concurrent with the early diversification of the Basidiomycota, followed by additional species-specific duplications and losses of a more recent origin. The quelling pathway possibly exists in most Basidiomycota; however, to date, no evidence for the meiotic silencing (MSUD) pathway has been found. Given that both argonaute and dicer are present, it should be possible to apply RNAi to study virulence genes in H. annosum s.l.

Authors/Creators:Hu, Yang
Title:Understanding virulence of Heterobasidion annosum s.l., a root rot pathogen of conifers
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :26 November 2015
Depositing date:26 November 2015
Number of Pages:67
IHu, Y., Stenlid, J., Elfstrand, M., Durling M. and Olson, Å. The conifer root rot pathogens Heterobasidion irregulare and Heterobasidion occidentale employ different strategies to infect Norway spruce (manuscript).
IIHu, Y., Stenlid, J., Elfstrand, M. and Olson, Å. 2013. Evolution of RNA interference proteins dicer and argonaute in Basidiomycota. Mycologia, 105, 1489-1498.
IIIHu, Y., Kim S., Jeon J., Elfstrand M., Stenlid J., Lee Y. and Olson, Å. Endo-rhamnogalacturonase associated with the in planta growth of Heterobasidion irregulare (manuscript).
Place of Publication:Uppsala
Publisher:Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-8434-9
ISBN for electronic version:978-91-576-8435-6
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:H Protection of plants and stored products > H20 Plant diseases
K Forestry > K70 Forest injuries and protection
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Microbiology (Microbiology in the medical area to be 30109)
(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Bioinformatics and Systems Biology (methods development to be 10203)
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Forest Science
Agrovoc terms:heterobasidion, pathogens, root rots, fungal diseases, pathogenicity, forest trees, pinophyta, pinus, picea abies, rna, gene expression
Keywords:Heterobasidion annosum sensu lato (s.l.), virulence, transcriptomes, RNAi, endo-rhamnogalacturonase
Permanent URL:
ID Code:12861
Faculty:S - Faculty of Forest Sciences
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
External funders:Swedish Foundation for Strategic Research
Deposited By: Mr Yang Hu
Deposited On:26 Nov 2015 14:07
Metadata Last Modified:10 Sep 2020 13:41

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