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Jarkko Hantula - One of the best experts on this subject based on the ideXlab platform.
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Heterobasidion partitivirus 13 mediates severe growth debilitation and major alterations in the gene expression of a fungal forest pathogen
Journal of Virology, 2017Co-Authors: Eeva J Vainio, Rafiqul Hyder, Tero Tuomivirta, Tuula Piri, Muhammad Kashif, Jaana Jurvansuu, Anna Poimala, Salla Makela, Dina Nitisa, Jarkko HantulaAbstract:The fungal genus Heterobasidion includes some of the most devastating conifer pathogens in the boreal forest region. In this study, we showed that the alphapartitivirus Heterobasidion partitivirus 13 from Heterobasidion annosum (HetPV13-an1) is the main causal agent of severe phenotypic debilitation in the host fungus. Based on RNA sequencing using isogenic virus-infected and cured fungal strains, HetPV13-an1 affected the transcription of 683 genes, of which 60% were downregulated and 40% upregulated. Alterations observed in carbohydrate and amino acid metabolism suggest that the virus causes a state of starvation, which is compensated for by alternative synthesis routes. We used dual cultures to transmit HetPV13-an1 into new strains of H. annosum and Heterobasidion parviporum. The three strains of H. parviporum that acquired the virus showed noticeable growth reduction on rich culturing medium, while only two of six H. annosum isolates tested showed significant debilitation. Based on reverse transcription-quantitative PCR (RT-qPCR) analysis, the response toward HetPV13-an1 infection was somewhat different in H. annosum and H. parviporum. We assessed the effects of HetPV13-an1 on the wood colonization efficacy of H. parviporum in a field experiment where 46 Norway spruce trees were inoculated with isogenic strains with or without the virus. The virus-infected H. parviporum strain showed considerably less growth within living trees than the isolate without HetPV13-an1, indicating that the virus also causes growth debilitation in natural substrates. IMPORTANCE A biocontrol method restricting the spread of Heterobasidion species would be highly beneficial to forestry, as these fungi are difficult to eradicate from diseased forest stands and cause approximate annual losses of €800 million in Europe. We used virus curing and reintroduction experiments and RNA sequencing to show that the alphapartitivirus HetPV13-an1 affects many basic cellular functions of the white rot wood decay fungus Heterobasidion annosum, which results in aberrant hyphal morphology and a low growth rate. Dual fungal cultures were used to introduce HetPV13-an1 into a new host species, Heterobasidion parviporum, and field experiments confirmed the capability of the virus to reduce the growth of H. parviporum in living spruce wood. Taken together, our results suggest that HetPV13-an1 shows potential for the development of a future biocontrol agent against Heterobasidion fungi.
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Distribution of Viruses Inhabiting Heterobasidion annosum in a Pine-Dominated Forest Plot in Southern Finland
Microbial Ecology, 2017Co-Authors: Rafiqul Hyder, Heikki Nuorteva, Tuula Piri, Jarkko Hantula, Eeva J VainioAbstract:We investigated the diversity and spatial distribution of viruses infecting strains of the root rot fungus Heterobasidion annosum collected from pine stumps at a heavily infected forest site. Four different partitiviruses were detected in 14 H. annosum isolates at the study site, constituting approximately 29% of all Heterobasidion isolates investigated (N = 48). Two of the viruses detected were new partitiviruses designated here as Heterobasidion partitivirus 16 (HetPV16) and HetPV20, and two were previously known partitiviruses: HetPV7 and HetPV13. The two new partitiviruses found, HetPV16-an1 and HetPV20-an1, shared ~70% RdRp nucleotide sequence identity with the alphapartitivirus Rosellinia necatrix partitivirus 2, and less than 40% identity with known viruses of Heterobasidion spp. HetPV7-an1 was closely similar to HetPV7-pa1 isolated earlier from Heterobasidion parviporum, supporting the view of conspecific virus pools in different Heterobasidion species. Three fungal isolates were found to be co-infected with two different partitivirus strains (HetPV7-an1 and HetPV13-an2 or HetPV16-an1 and HetPV20-an1). Different isolates representing each host clone had variable virus compositions, and virus strains occurring in more than one host clone showed minor sequence variations between clones.
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occurrence of similar mycoviruses in pathogenic saprotrophic and mycorrhizal fungi inhabiting the same forest stand
FEMS Microbiology Ecology, 2017Co-Authors: Eeva J Vainio, Taina Pennanen, Tiina Rajala, Jarkko HantulaAbstract:: Fungal viruses (mycoviruses) are considered to be highly host specific, but phylogenetic analysis supports the occasional occurrence of horizontal transmission between species. We used an extensive sampling strategy to investigate whether similar viruses occur in more than one fungal species of the same forest habitat. Mycelial samples were collected from in-growth mesh bags (N = 259), fruiting bodies (N = 173) and cultured isolates (N = 68) at a forest site where the spatial distribution of viral infections in clonal individuals of the wood decay fungus Heterobasidion parviporum was mapped in detail earlier. The investigation revealed previously known Heterobasidion viruses in ∼2% of the single or pooled mycorrhizal samples from mesh bags, ∼3% of the fruiting body samples and none of the fungal cultures analyzed. Novel virus strains distinct from known Heterobasidion viruses were detected in cultures of ectomycorrhizal fungi (Lactarius tabidus, L. rufus) and saprotrophic fungi (Megacollybia platyphylla, Mucoraceae spp.). Overall, our results support the view that mycoviruses do not readily cross species borders. Regarding potential virocontrol applications, the introduction of Heterobasidion viruses into natural habitats is not expected to cause a major infection pressure towards the indigenous fungal community. However, the ecological consequences of the putative interspecies virus transmission events detected require further investigation.
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Heterobasidion wood decay fungi host diverse and globally distributed viruses related to helicobasidium mompa partitivirus v70
Virus Research, 2015Co-Authors: Muhammad Kashif, Rafiqul Hyder, Jarkko Hantula, D De Vega Perez, Eeva J VainioAbstract:Abstract Viruses of the Partitiviridae family occur at a relatively low frequency in the fungal genus Heterobasidion, but show high genetic diversity. Here, we describe four novel partitivirus species that infect three Heterobasidion species that are pathogens of conifers: H. annosum, H. parviporum and H. irregulare. We show that these viruses, designated Heterobasidion partitivirus 12 (HetPV12), HetPV13, HetPV14 and HetPV15, form a phylogenetically distinct clade together with the previously described Heterobasidion partitivirus 3 (HetPV3) found in the H. insulare species complex and Helicobasidium mompa partitivirus V70, both members of the genus Alphapartitivirus. Closely related strains of HetPV13 (over 97% polymerase identity at the nucleotide level) occur in H. annosum and H. parviporum, suggesting recent transmission of this virus species between the two fungal host species. Moreover, the occurrence of nearly identical HetPV13 strains in Finland and Poland (ca 1400 km apart) indicates that the dispersal capacity of Heterobasidion partitiviruses is high. Viruses related to HetPV3 have a global distribution but only ca 2.7% overall prevalence among isolates of Heterobasidion. In three cases, these HetPV3-related viruses co-infected their hosts with distantly related partitiviruses or Heterobasidion RNA virus 6.
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molecular characterization of hetrv8 ir1 a partitivirus of the invasive conifer pathogenic fungus Heterobasidion irregulare
Archives of Virology, 2013Co-Authors: Eeva J Vainio, Paolo Capretti, Emma Motta, Jarkko HantulaAbstract:The Heterobasidion annosum (Fr.) Bref. complex includes some of the most destructive conifer pathogenic fungi in the Boreal forest region. H. irregulare, formerly known as the North American pine type of H. annosum, was introduced from North America into Italy during the Second World War and occurs as an invasive pathogen in Pinus pinea stands together with the native European species H. annosum sensu stricto. We describe the complete nucleotide sequence of a new putative partitivirus from an Italian strain of H. irregulare. The bisegmented genome of HetRV8-ir1 encodes an RNA-dependent RNA polymerase of 704 aa and a capsid protein of 638 aa. The polymerase and capsid aa sequences are relatively similar (59-78 %) to those of Fusarium poae virus 1, Pleurotus ostreatus virus 1, and grapevine-associated partitivirus 1. HetRV8-ir1 is the first virus described from H. irregulare, and it is distantly related to previously known partitiviruses of Heterobasidion species.
Eeva J Vainio - One of the best experts on this subject based on the ideXlab platform.
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mitoviruses in the conifer root rot pathogens Heterobasidion annosum and h parviporum
Virus Research, 2019Co-Authors: Eeva J VainioAbstract:Abstract Mitoviral infections are highly common among fungi, but so far only one mitovirus has been described in Heterobasidion spp. conifer pathogens. Here, the occurrence of further mitoviruses was investigated using a previously published RNA-Seq dataset for de novo contig assembly. This allowed the identification of two additional mitovirus strains designated as Heterobasidion mitovirus 2 (HetMV2) and HetMV3 with genome lengths of ca. 2.9 and 5.0 kb. Furthermore, the occurrence of similar viruses was screened among a collection of Heterobasidion isolates using RT-PCR. Mitoviruses were detected in six more fungal isolates and two different host species, H. annosum and H. parviporum.
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Heterobasidion partitivirus 13 mediates severe growth debilitation and major alterations in the gene expression of a fungal forest pathogen
Journal of Virology, 2017Co-Authors: Eeva J Vainio, Rafiqul Hyder, Tero Tuomivirta, Tuula Piri, Muhammad Kashif, Jaana Jurvansuu, Anna Poimala, Salla Makela, Dina Nitisa, Jarkko HantulaAbstract:The fungal genus Heterobasidion includes some of the most devastating conifer pathogens in the boreal forest region. In this study, we showed that the alphapartitivirus Heterobasidion partitivirus 13 from Heterobasidion annosum (HetPV13-an1) is the main causal agent of severe phenotypic debilitation in the host fungus. Based on RNA sequencing using isogenic virus-infected and cured fungal strains, HetPV13-an1 affected the transcription of 683 genes, of which 60% were downregulated and 40% upregulated. Alterations observed in carbohydrate and amino acid metabolism suggest that the virus causes a state of starvation, which is compensated for by alternative synthesis routes. We used dual cultures to transmit HetPV13-an1 into new strains of H. annosum and Heterobasidion parviporum. The three strains of H. parviporum that acquired the virus showed noticeable growth reduction on rich culturing medium, while only two of six H. annosum isolates tested showed significant debilitation. Based on reverse transcription-quantitative PCR (RT-qPCR) analysis, the response toward HetPV13-an1 infection was somewhat different in H. annosum and H. parviporum. We assessed the effects of HetPV13-an1 on the wood colonization efficacy of H. parviporum in a field experiment where 46 Norway spruce trees were inoculated with isogenic strains with or without the virus. The virus-infected H. parviporum strain showed considerably less growth within living trees than the isolate without HetPV13-an1, indicating that the virus also causes growth debilitation in natural substrates. IMPORTANCE A biocontrol method restricting the spread of Heterobasidion species would be highly beneficial to forestry, as these fungi are difficult to eradicate from diseased forest stands and cause approximate annual losses of €800 million in Europe. We used virus curing and reintroduction experiments and RNA sequencing to show that the alphapartitivirus HetPV13-an1 affects many basic cellular functions of the white rot wood decay fungus Heterobasidion annosum, which results in aberrant hyphal morphology and a low growth rate. Dual fungal cultures were used to introduce HetPV13-an1 into a new host species, Heterobasidion parviporum, and field experiments confirmed the capability of the virus to reduce the growth of H. parviporum in living spruce wood. Taken together, our results suggest that HetPV13-an1 shows potential for the development of a future biocontrol agent against Heterobasidion fungi.
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Distribution of Viruses Inhabiting Heterobasidion annosum in a Pine-Dominated Forest Plot in Southern Finland
Microbial Ecology, 2017Co-Authors: Rafiqul Hyder, Heikki Nuorteva, Tuula Piri, Jarkko Hantula, Eeva J VainioAbstract:We investigated the diversity and spatial distribution of viruses infecting strains of the root rot fungus Heterobasidion annosum collected from pine stumps at a heavily infected forest site. Four different partitiviruses were detected in 14 H. annosum isolates at the study site, constituting approximately 29% of all Heterobasidion isolates investigated (N = 48). Two of the viruses detected were new partitiviruses designated here as Heterobasidion partitivirus 16 (HetPV16) and HetPV20, and two were previously known partitiviruses: HetPV7 and HetPV13. The two new partitiviruses found, HetPV16-an1 and HetPV20-an1, shared ~70% RdRp nucleotide sequence identity with the alphapartitivirus Rosellinia necatrix partitivirus 2, and less than 40% identity with known viruses of Heterobasidion spp. HetPV7-an1 was closely similar to HetPV7-pa1 isolated earlier from Heterobasidion parviporum, supporting the view of conspecific virus pools in different Heterobasidion species. Three fungal isolates were found to be co-infected with two different partitivirus strains (HetPV7-an1 and HetPV13-an2 or HetPV16-an1 and HetPV20-an1). Different isolates representing each host clone had variable virus compositions, and virus strains occurring in more than one host clone showed minor sequence variations between clones.
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occurrence of similar mycoviruses in pathogenic saprotrophic and mycorrhizal fungi inhabiting the same forest stand
FEMS Microbiology Ecology, 2017Co-Authors: Eeva J Vainio, Taina Pennanen, Tiina Rajala, Jarkko HantulaAbstract:: Fungal viruses (mycoviruses) are considered to be highly host specific, but phylogenetic analysis supports the occasional occurrence of horizontal transmission between species. We used an extensive sampling strategy to investigate whether similar viruses occur in more than one fungal species of the same forest habitat. Mycelial samples were collected from in-growth mesh bags (N = 259), fruiting bodies (N = 173) and cultured isolates (N = 68) at a forest site where the spatial distribution of viral infections in clonal individuals of the wood decay fungus Heterobasidion parviporum was mapped in detail earlier. The investigation revealed previously known Heterobasidion viruses in ∼2% of the single or pooled mycorrhizal samples from mesh bags, ∼3% of the fruiting body samples and none of the fungal cultures analyzed. Novel virus strains distinct from known Heterobasidion viruses were detected in cultures of ectomycorrhizal fungi (Lactarius tabidus, L. rufus) and saprotrophic fungi (Megacollybia platyphylla, Mucoraceae spp.). Overall, our results support the view that mycoviruses do not readily cross species borders. Regarding potential virocontrol applications, the introduction of Heterobasidion viruses into natural habitats is not expected to cause a major infection pressure towards the indigenous fungal community. However, the ecological consequences of the putative interspecies virus transmission events detected require further investigation.
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Heterobasidion wood decay fungi host diverse and globally distributed viruses related to helicobasidium mompa partitivirus v70
Virus Research, 2015Co-Authors: Muhammad Kashif, Rafiqul Hyder, Jarkko Hantula, D De Vega Perez, Eeva J VainioAbstract:Abstract Viruses of the Partitiviridae family occur at a relatively low frequency in the fungal genus Heterobasidion, but show high genetic diversity. Here, we describe four novel partitivirus species that infect three Heterobasidion species that are pathogens of conifers: H. annosum, H. parviporum and H. irregulare. We show that these viruses, designated Heterobasidion partitivirus 12 (HetPV12), HetPV13, HetPV14 and HetPV15, form a phylogenetically distinct clade together with the previously described Heterobasidion partitivirus 3 (HetPV3) found in the H. insulare species complex and Helicobasidium mompa partitivirus V70, both members of the genus Alphapartitivirus. Closely related strains of HetPV13 (over 97% polymerase identity at the nucleotide level) occur in H. annosum and H. parviporum, suggesting recent transmission of this virus species between the two fungal host species. Moreover, the occurrence of nearly identical HetPV13 strains in Finland and Poland (ca 1400 km apart) indicates that the dispersal capacity of Heterobasidion partitiviruses is high. Viruses related to HetPV3 have a global distribution but only ca 2.7% overall prevalence among isolates of Heterobasidion. In three cases, these HetPV3-related viruses co-infected their hosts with distantly related partitiviruses or Heterobasidion RNA virus 6.
Jan Stenlid - One of the best experts on this subject based on the ideXlab platform.
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infection and spread of root rot caused by Heterobasidion spp in pinus contorta plantations in northern europe three case studies
Canadian Journal of Forest Research, 2019Co-Authors: Astra Zaļuma, Tālis Gaitnieks, Jan Stenlid, Indriķis Muižnieks, Natālija Burņevica, āris Jansons, Jurģis Jansons, R VasaitisAbstract:This study investigated the origins and spread patterns of Heterobasidion root disease in three Pinus contorta Dougl. ex Loudon plantations established on forest and agricultural land and subjected...
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evolutionary history of the conifer root rot fungus Heterobasidion annosum sensu lato
Molecular Ecology, 2010Co-Authors: Kerstin Dalman, Åke Olson, Jan StenlidAbstract:We investigated two hypotheses for the origin of the root rot fungus Heterobasidion annosum species complex: (i) that geology has been an important factor for the speciation (ii) that co-evolutionary processes with the hosts drove the divergence of the pathogen species. The H. annosum species complex consists of five species: three occur in Europe, H. annosum s.s., Heterobasidion parviporum and Heterobasidion abietinum, and two in North America, Heterobasidion irregulare and Heterobasidion occidentale; all with different but partially overlapping host preferences. The evolution of the H. annosum species complex was studied using six partially sequenced genes, between 10 and 30 individuals of each species were analysed. Neighbour-joining trees were constructed for each gene, and a Bayesian tree was built for the combined data set. In addition, haplotype networks were constructed to illustrate the species relationships. For three of the genes, H. parviporum and H. abietinum share haplotypes supporting recent divergence and/or possible gene flow. We propose that the H. annosum species complex originated in Laurasia and that the H. annosum s.s./H. irregulare and H. parviporum/H. abietinum/H. occidentale ancestral species emerged between 45 and 60 Ma in the Palaearctic, well after the radiation of the host genera. Our data imply that H. irregulare and H. occidentale were colonizing North America via different routes. In conclusion, plate tectonics are likely to have been the main factor influencing Heterobasidion speciation and biogeography.
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development of a rapid and simple agrobacterium tumefaciens mediated transformation system for the fungal pathogen Heterobasidion annosum
Fems Microbiology Letters, 2006Co-Authors: Nicklas Samils, Åke Olson, Malin Elfstrand, Daniel L. Czederpiltz, Jan Fahleson, Christina Dixelius, Jan StenlidAbstract:Heterobasidion annosum causes root and butt-rot in trees and is the most serious forest pathogen in the northern hemisphere. We developed a rapid and simple Agrobacterium-mediated method of gene delivery into H. annosum to be used in functional studies of candidate genes and for visualization of mycelial interactions. Heterobasidion annosum TC 32-1 was cocultivated at pH 5.6 and 20°C in Hagems medium with Agrobacterium tumefaciens C58 carrying plasmids with hygromycin B resistance as the selectable marker and green fluorescent protein as a visual marker. We obtained 18 mitotically stable transformed isolates showing green fluorescence protein activity.
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conifer root and butt rot caused by Heterobasidion annosum fr bref s l
Molecular Plant Pathology, 2005Co-Authors: Fred O. Asiegbu, Aleksandra Adomas, Jan StenlidAbstract:SUMMARY The root and butt rot caused by Heterobasidon annosum is one of the most destructive diseases of conifers in the northern temperate regions of the world, particularly in Europe. Economic losses attributable to Heterobasidion infection in Europe are estimated at 800 million euros annually. The fungus has been classified into three separate European intersterile species P ( H. annosum ), S ( H. parviporum ) and F ( H. abietinum ) based on their main host preferences: pine, spruce and fir, respectively. In North America, two intersterile groups are present, P and S/F, but these have not been given scientific names. The ecology of the disease spread has been intensively studied but the genetics, biochemistry and molecular aspects of pathogen virulence have been relatively little examined. Recent advances in transcript profiling, molecular characterization of pathogenicity factors and establishment of DNA-transformation systems have paved the way for future advances in our understanding of this pathosystem. Taxonomy: Heterobasidion annosum (Fr.) Bref., H. parviporum Niemela & Korhonen and H. abietinum Niemela & Korhonen; kingdom Fungi; class Basidiomycotina; order Aphyllophorales; family Bondarzewiaceae; genus Heterobasidion . Identification: presence of the fungus fruit bodies, basidiocarps whitish in the margins, upper surface is tan to dark brown, usually irregular shaped, 3.5 ( − 7) cm thick and up to 40 cm in diameter; pores 5‐19, 7‐22 and 13‐26 mm 2 for the P, F and S groups, respectively. Small brownish non-sporulating postules develop on the outside of infected roots. Asexual spores (conidiospores) are 3.8‐6.6 × 2.8‐5.0 µ m in size. Mating tests are necessary for identification of intersterility groups. Host range: The fungus attacks many coniferous tree species. In Europe, particularly trees of the genera Pinus and Juniperus (P), Picea (S), Abies (F) and in North America Pinus (P) and Picea , Tsuga and Abies (S/F). To a lesser extent it causes root rot on some decidous trees ( Betula and Quercus ). Disease symptoms: symptoms (e.g. exhudation of resin, crown deterioration) due to Heterobasidion root rot in living trees are not particularly characteristic and in most cases cannot be distinguished from those caused by other root pathogens. Heterobasidion annosum s.l. is a white rot fungus. Initial growth in wood causes a stain that varies in colour depending on host tree species. Incipient decay is normally pale yellow and it develops into a light brown decay to become a white pocket rot with black flecks in its advanced stage. Control: silvicultural methods (e.g. stump removal), chemicals (urea, borates) and biological control agent ( Phlebiopsis gigantea , marketed as PG Suspension® in the UK, PG IBL® in Poland and Rotstop® in Fennoscandia) are commonly used approaches for minimizing the disease spread.
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comparison of five strains of phlebiopsis gigantea and two trichoderma formulations for treatment against natural Heterobasidion spore infections on norway spruce stumps
Scandinavian Journal of Forest Research, 2005Co-Authors: Mattias Berglund, Jonas Ronnberg, Lillian Holmer, Jan StenlidAbstract:In an experiment established on three Norway spruce sites in southern Sweden, the ability of five strains of Phlebiopsis gigantea, including the commercial strain Rotstop®, and two Trichoderma formulations to control natural Heterobasidion spp. spore infections was compared. At each site 160 trees were felled, and the resulting stumps were treated with spore suspensions of the seven fungal preparations. Twenty stumps at each site were left untreated as control stumps. When sampled 9 months after treatment, two of the P. gigantea strains (1984 and 1985) were the most effective at preventing infection by Heterobasidion spp. The other three P. gigantea strains were less effective, and two Trichoderma formulations did not significantly reduce Heterobasidion spp. infections.
Matteo Garbelotto - One of the best experts on this subject based on the ideXlab platform.
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molecular analyses identify hybridization mediated nuclear evolution in newly discovered fungal hybrids
Ecology and Evolution, 2019Co-Authors: Fabiano Sillo, Matteo Garbelotto, Paolo Gonthier, Blakey Lockman, Takao KasugaAbstract:Hybridization may be a major driver in the evolution of plant pathogens. In a high elevation Alpine larch stand in Montana, a novel hybrid fungal pathogen of trees originating from the mating of Heterobasidion irregulare with H. occidentale has been recently discovered. In this study, sequence analyses of one mitochondrial and four nuclear loci from 11 Heterobasidion genotypes collected in the same Alpine larch stand indicated that hybridization has increased allelic diversity by generating novel polymorphisms unreported in either parental species. Sequence data and ploidy analysis through flow cytometry confirmed that heterokaryotic (n + n) genotypes were not first-generation hybrids, but were the result of multiple backcrosses, indicating hybrids are fertile. Additionally, all admixed genotypes possessed the H. occidentale mitochondrion, indicating that the hybrid progeny may have been backcrossing mostly with H. occidentale. Based on reticulate phylogenetic network analysis by PhyloNet, Bayesian assignment, and ordination tests, alleles can be defined as H. irregulare-like or H. occidentale-like. H. irregulare-like alleles are clearly distinct from all known H. irregulare alleles and are derived from the admixing of both Heterobasidion species. Instead, all but one H. occidentale alleles found in hybrids, although novel, were not clearly distinct from alleles found in the parental H. occidentale population. This discovery demonstrates that Alpine larch can be a universal host favouring the interspecific hybridization between H. irregulare and H. occidentale and the hybridization-mediated evolution of a nucleus, derived from H. irregulare parental species but clearly distinct from it.
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First Report of Heterobasidion occidentale on Sequoia sempervirens in Northern California
Plant Disease, 2017Co-Authors: Matteo Garbelotto, Maria Friedman, W Bedell, Terry W. HenkelAbstract:In 2007, Heterobasidion basidiocarps (“fruit bodies”) were found on 37 of 200 coast redwood (Sequoia sempervirens) stumps surveyed in four stands owned by the Green Diamond Resource Company near McKinleyville, CA (Humboldt County). All were second or third growth stands, last logged 7-13 years prior to the survey here described. In 2015, during a second follow-up survey, 10 fruit bodies and two rotted wood samples were collected from 10 separate stumps, their DNA was extracted, and the Internal Transcribed Spacer was amplified and sequenced using the ITS1f-ITS4b primers described by Gardes and Bruns (1993). All sequences (e.g. GenBank Accession No. MF488718) had a 99-100% homology with ITS sequences of Heterobasidion occidentale (e.g. Accession No. KC492946), a widespread root and butt rot agent common on Abies, Picea, and Tsuga spp. in western North America, and also found on Sequoiadendron giganteum in the Central Sierra Nevada (Garbelotto and Gonthier 2013). Sapwood in 97% (range 96-100%) of the 200 st...
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Geographical coordinates
2016Co-Authors: Matteo Garbelotto, Fabio Guglielmo, Silvia Mascheretti, Peter J. P. Croucher, Paolo GonthierAbstract:Data file including the latitude and longitude coordinates (expressed in UTM) of the collection points of the Heterobasidion irregulare isolates submitted to SSR analysis
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inferences on the phylogeography of the fungal pathogen Heterobasidion annosum including evidence of interspecific horizontal genetic transfer and of human mediated long range dispersal
Molecular Phylogenetics and Evolution, 2008Co-Authors: Rachel Linzer, Paolo Gonthier, William J Otrosina, J Bruhn, G Laflamme, G Bussieres, Matteo GarbelottoAbstract:Fungi in the basidiomycete species complex Heterobasidion annosum are significant root-rot pathogens of conifers throughout the northern hemisphere. We utilize a multilocus phylogenetic approach to examine hypotheses regarding the evolution and divergence of two Heterobasidion taxa associated with pines: the Eurasian H. annosum sensu stricto and the North American H. annosum P intersterility group (ISG). Using DNA sequence information from portions of two nuclear and two mitochondrial loci, we infer phylogenetic relationships via parsimony, Bayesian and median-joining network analysis. Analysis of isolates representative of the entire known geographic range of the two taxa results in monophyletic sister Eurasian and North American lineages, with North America further subdivided into eastern and western clades. Genetically anomalous isolates from the Italian presidential estate of Castelporziano are always part of a North American clade and group with eastern North America, upholding the hypothesis of recent, anthropogenically mediated dispersal. P ISG isolates from Mexico have phylogenetic affinity with both eastern and western North America. Results for an insertion in the mitochondrial rDNA suggest this molecule was obtained from the Heterobasidion S ISG, a taxon sympatric with the P ISG in western North America. These data are compatible with an eastern Eurasian origin of the species, followed by dispersal of two sister taxa into western Eurasia and into eastern North America over a Beringean land bridge, a pattern echoed in the phylogeography of other conifer-associated basidiomycetes.
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invasion of european pine stands by a north american forest pathogen and its hybridization with a native interfertile taxon
Molecular Ecology, 2007Co-Authors: Paolo Gonthier, Rachel Linzer, Giovanni Nicolotti, F Guglielmo, Matteo GarbelottoAbstract:It was recently reported that North American (NA) individuals of the forest pathogen Heterobasidion annosum were found in a single pine stand near Rome, in association with the movement of US troops during World War II. Here, we report on some aspects of the invasion biology of this pathogen in Italian coastal pinewoods, and on its interaction with native (EU) Heterobasidion populations. Spores of Heterobasidion were sampled using woody traps in pine stands along 280 km of coast around Rome. DNA of single-spore colonies was characterized by two sets of nuclear and one set of mitochondrial taxon-specific polymerase chain reaction primers. NA spores were found not only in a single site, but in many locations over a wide geographic area. Invasion occurred at an estimated rate of 1.3 km/year through invasion corridors provided by single trees, and not necessarily by sizable patches of forests. Within the 100-km long range of expansion, the NA taxon was dominant in all pure pine stands. Because abundance of the EU taxon is low and identical among stands within and outside the area invaded by NA individuals, we infer that the exotic population has invaded habitats mostly unoccupied by the native species. Discrepancy between a mitochondrial and a nuclear marker occurred in 3.8% of spores from one site, a mixed oak-pine forest where both taxa were equally represented. Combined phylogenetic analyses on nuclear and mitochondrial loci confirmed these isolates were recombinant. The finding of hybrids indicates that genetic interaction between NA and EU Heterobasidion taxa is occurring as a result of their current sympatry.
Paolo Gonthier - One of the best experts on this subject based on the ideXlab platform.
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Inferences on the Susceptibility of Wood of Different Tree Species to Heterobasidion annosum Sensu Lato Primary Infections and on the Range of Pathogen Spores Dispersal
'MDPI AG', 2021Co-Authors: Lauma Brūna, Kristīne Kenigsvalde, Tālis Gaitnieks, Astra Zaļuma, Natālija Burņevica, Guglielmo Lione, Dārta Kļaviņa, Paolo GonthierAbstract:Stumps play a pivotal role in the epidemiology of the fungal forest pathogens Heterobasidion spp. because they are the main courts of primary airborne infections. The aims of this study were (i) to determine the susceptibility of seven tree species (i.e., Larix sibirica, Picea abies, Picea sitchensis, Pinus contorta, Pinus strobus, Pinus sylvestris and Pseudotsuga menziesii) to primary infection by H. annosum and H. parviporum through comparative inoculation experiments of conidia on wood discs in controlled conditions; (ii) to compare the susceptibility of wood discs of the same tree species to natural airborne infections in two Latvian Norway spruce forest stands infested either by H. annosum or H. parviporum; (iii) to explore the rates of infection of wood discs at increasing distances from spore sources in these two forests to make inferences on the range of spores dispersal. Results obtained by spraying wood discs with conidial suspensions in controlled conditions are in agreement with those obtained by exposing wood discs to the natural airborne inoculum in the forests, as clearly supported by the significant correlation (r = 0.79; p Pinus species, followed by P. abies and P. sitchensis. Susceptibility was lowest for L. sibirica and P. menziesii. The area colonized by Heterobasidion spp. in the sapwood of wood discs was much greater than that colonized in the heartwood. A sharp decrease in the rate of infection of wood discs with distance from spore sources (i.e., fruiting bodies) was observed, further confirming the importance of local spore sources in the epidemiology of Heterobasidion spp. Taken together, these findings could help designing tactics to manage these fungal forest pathogens
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molecular analyses identify hybridization mediated nuclear evolution in newly discovered fungal hybrids
Ecology and Evolution, 2019Co-Authors: Fabiano Sillo, Matteo Garbelotto, Paolo Gonthier, Blakey Lockman, Takao KasugaAbstract:Hybridization may be a major driver in the evolution of plant pathogens. In a high elevation Alpine larch stand in Montana, a novel hybrid fungal pathogen of trees originating from the mating of Heterobasidion irregulare with H. occidentale has been recently discovered. In this study, sequence analyses of one mitochondrial and four nuclear loci from 11 Heterobasidion genotypes collected in the same Alpine larch stand indicated that hybridization has increased allelic diversity by generating novel polymorphisms unreported in either parental species. Sequence data and ploidy analysis through flow cytometry confirmed that heterokaryotic (n + n) genotypes were not first-generation hybrids, but were the result of multiple backcrosses, indicating hybrids are fertile. Additionally, all admixed genotypes possessed the H. occidentale mitochondrion, indicating that the hybrid progeny may have been backcrossing mostly with H. occidentale. Based on reticulate phylogenetic network analysis by PhyloNet, Bayesian assignment, and ordination tests, alleles can be defined as H. irregulare-like or H. occidentale-like. H. irregulare-like alleles are clearly distinct from all known H. irregulare alleles and are derived from the admixing of both Heterobasidion species. Instead, all but one H. occidentale alleles found in hybrids, although novel, were not clearly distinct from alleles found in the parental H. occidentale population. This discovery demonstrates that Alpine larch can be a universal host favouring the interspecific hybridization between H. irregulare and H. occidentale and the hybridization-mediated evolution of a nucleus, derived from H. irregulare parental species but clearly distinct from it.
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comparative transcriptional and metabolic responses of pinus pinea to a native and a non native Heterobasidion species
Tree Physiology, 2018Co-Authors: Alessia Lucia Pepori, Paolo Gonthier, Marco Michelozzi, Alberto Santini, Gabriele Cencetti, Pierluigi Bonello, Federico Sebastiani, Nicola LuchiAbstract:Heterobasidion irregulare is a causal agent of root and butt-rot disease in conifers, and is native to North America. In 1944 it was introduced in central Italy in a Pinus pinea stand, where it shares the same niche with the native species Heterobasidion annosum. The introduction of a non-native pathogen may have significant negative effects on a naive host tree and the ecosystem in which it resides, requiring a better understanding of the system. We compared the spatio-temporal phenotypic, transcriptional and metabolic host responses to inoculation with the two Heterobasidion species in a large experiment with P. pinea seedlings. Differences in length of lesions at the inoculation site (IS), expression of host genes involved in lignin pathway and in cell rescue and defence, and analysis of terpenes at both IS and 12 cm above the IS (distal site, DS), were assessed at 3, 14 and 35 days post inoculation (dpi). Results clearly showed that both species elicit similar physiological and biochemical responses in P. pinea seedlings. The analysis of host transcripts and total terpenes showed differences between inoculation sites and between pathogen and mock inoculated plants. Both pathogen and mock inoculations induced antimicrobial peptide and phenylalanine ammonia-lyase overexpression at IS beginning at 3 dpi; while at DS all the analysed genes, except for peroxidase, were overexpressed at 14 dpi. A significantly higher accumulation of terpenoids was observed at 14 dpi at IS, and at 35 dpi at DS. The terpene blend at IS showed significant variation among treatments and sampling times, while no significant differences were ever observed in DS tissues. Based on our results, H. irregulare does not seem to have competitive advantages over the native species H. annosum in terms of pathogenicity towards P. pinea trees; this may explain why the non-native species has not widely spread over the 73 years since its putative year of introduction into central Italy.
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Geographical coordinates
2016Co-Authors: Matteo Garbelotto, Fabio Guglielmo, Silvia Mascheretti, Peter J. P. Croucher, Paolo GonthierAbstract:Data file including the latitude and longitude coordinates (expressed in UTM) of the collection points of the Heterobasidion irregulare isolates submitted to SSR analysis
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Identification of genes differentially expressed during the interaction between the plant symbiont Suillus luteus and two plant pathogenic allopatric Heterobasidion species
Mycological Progress, 2015Co-Authors: Fabiano Sillo, Elisa Zampieri, Luana Giordano, Gianni Lione, Jan V. Colpaert, Raffaella Balestrini, Paolo GonthierAbstract:The effects of biological invasions by non-native species have been widely studied in terms of environmental, economic, and human health impacts. However, little is known about the consequences that non-native plant pathogens may determine on host plant symbionts, such as ectomycorrhizal (ECM) fungi. In this study, interactions between Suillus luteus, an ECM fungus of pine trees, and the allopatrically differentiated fungal pathogens of pines Heterobasidion irregulare and H. annosum were investigated in dual culture by morphological and gene expression analyses. Growth of S. luteus was inhibited by both Heterobasidion species, but based on statistical analysis, growth inhibition was due to the isolate rather than to the species. The expression analysis on genes related to cell wall hydrolytic enzymes and hydrophobins, putatively involved in the fungus–fungus interaction, allowed to identify significantly up- and down-regulated genes both in the symbiont and in the pathogens. Based on the transcript analysis, it was not possible to distinguish the impact of the two pathogenic species on the ECM fungus. The only exception was a S. luteus gene coding for a putative chitinase (SlGH18_8356) that was found to be differentially regulated during interaction with H. irregulare compared to H. annosum.