Population structure of <i>Heterobasidion annosum</i> from North America and Europe

Otrosina, William J.; Chase, Thomas E.; Cobb, F. W.; Korhonen, Kari T.

doi:10.1139/b93-123

Cited by 72 publications

(52 citation statements)

References 26 publications

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“…It should be noted that although the two North American taxa are still referred to as "ISGs" and are awaiting formal species description, there is no doubt they represent different species. Significant intersterility between them, differential host association, and all genetic evidence published so far indicate that the two are relatively distant taxa within the species complex (2,16,19,23,24,31,35,44).…”

mentioning

confidence: 96%

Ecological Constraints Limit the Fitness of Fungal Hybrids in the Heterobasidion annosum Species Complex

Garbelotto

Gonthier

Nicolotti

2007

Appl Environ Microbiol

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The ability of two closely related species to maintain species boundaries in spite of retained interfertility between them is a documented driving force of speciation. Experimental evidence to support possible interspecific postzygotic isolation mechanisms for organisms belonging to the kingdom Fungi is still missing. Here we report on the outcome of a series of controlled comparative inoculation experiments of parental wild genotypes and F 1 hybrid genotypes between closely related and interfertile taxa within the Heterobasidion annosum fungal species complex. Results indicated that these fungal hybrids are not genetically unfit but can fare as well as parental genotypes when inoculated on substrates favorable to both parents. However, when placed in substrates favoring one of the parents, hybrids are less competitive than the parental genotypes specialized on that substrate. Furthermore, in some but not all fungus ؋ plant combinations, a clear asymmetry in fitness was observed between hybrids carrying identical nuclear genomes but different cytoplasms. This work provides some of the first experimental evidence of ecologically driven postzygotic reinforcement of isolation between closely related fungal species characterized by marked host specificity. Host specialization is one of the most striking traits of a large number of symbiotic and parasitic fungi; thus, we suggest the ecological mechanism proven here to reinforce isolation among Heterobasidion spp. may be generally valid for host-specialized fungi. The validity of this generalization is supported by the low number of known fungal hybrids and by their distinctive feature of being found in substrates different from those colonized by parental species.

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mentioning

confidence: 96%

Ecological Constraints Limit the Fitness of Fungal Hybrids in the Heterobasidion annosum Species Complex

Garbelotto

Gonthier

Nicolotti

2007

Appl Environ Microbiol

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“…H. annosum, in fact, comprises at least three intersterility groups (ISGs) that display marked host preferences (9,61). Furthermore, each ISG is subdivided in genetically isolated populations according to their broad geographic provenance (18,35). Different ISGs cause distinct symptoms on each host species, and host-specific dynamics affect infection and spread (26,36).…”

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confidence: 99%

Genetic Structure of Heterobasidion annosum in White Fir Mortality Centers in California

Garbelotto¹,

Cobb²,

Bruns³

et al. 1999

Phytopathology®

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ABSTRACT.Garbelotto, M., Cobb, F. W., Bruns, T. D., Otrosina, W. J., Popenuck, T., and Slaughter, G. 1999. Genetic structure of in white fir mortality centers in California. Phytopathology 89546-554.The structure of Heterobasidion annosum populations was studied in 1.5 mixed-conifer sites in central and northern California. Study sites displayed mortality of white fir trees in enlarging discrete patches (mortality centers). At each site, fungal genotypes were defined by somatic compatibility tests. In two sites, further genetic and molecular analyses were performed on field genotypes and on homokaryons obtained by dedikaryotization of field heterokaryons. Isolates were found to be colonizing mostly the roots and the bole sapwood of white fir trees, and no significant infections of other tree species were observed. Each mortality center was characterized by the presence of several fungal genotypes, all belonging to the S intersterility group. Both homokaryotic and heterokaryotic strains were present in all sites. Multiple genotypes were retrieved in individual trees or stumps. Out of 228 fungal genotypes, 86% were found only within a single tree or stump, while 14% had spread to adjacent trees. The two largest genotypes had diameters of 9 and 10 m, and had colonized five and nine trees, stumps, or both, respectively. The maximum distance between two adjacent trees colonized by the same genotype was 6 m, and a highly significant correlation was found between tree diameter and distance of fungal "vegetative" spread. The largest clones were found in areas characterized by high tree and stump densities, and secondary spread of the fungus was more significant in denser stands. In most cases, original infection courts of existing genotypes could be traced to standing trees and not to stumps. The genetic analysis performed in two mortality centers revealed that most local genotypes had different mating alleles, and thus originated from unrelated basidiospores. In a few cases, the same mating allele was shared by two heterokaryons (n+n genome) or by a homokaryon (n genome) and a heterokaryon. Molecular analysis showed that nuclei bearing the same mating allele were identical, providing evidence that the two nuclei forming heterokaryons can act independently in the field and can be shared among isolates, presumably via di-mon mating or by separate matings of different portions of widespread homokaryons.

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“…species complex was long regarded as a single cosmopolitan species with a wide host range, but mating experiments have revealed the existence of five separate Heterobasidion species showing differences in their host tree preferences (Korhonen 1978a, Chase and Ullrich 1988, Capretti et al 1990, Korhonen et al 1992, Niemelä and Korhonen 1998. Differentiation between these biological species has been confirmed using numerous different molecular approaches including isoenzyme analysis (Karlsson and Stenlid 1991, Otrosina et al 1993, Maijala et al 1995, Goggioli et al 1998), fatty acid and sterol profiles (Müller et al 1995), and various genetic marker molecules (Fabritius and Karjalainen 1993, Kasuga et al 1993, Stenlid et al 1994, La Porta et al 1997, Garbelotto et al 1998, Goggioli et al 1998, Vainio et al 1999, Kasuga and Mitchelson 2000, Johannesson and Stenlid 2003, Maijala et al 2003.…”

Section: Heterobasidion Annosum Species Complexmentioning

confidence: 98%

“…have also been identified from North America, designated as the North American P and S intersterility groups (Chase and Ullrich 1988, Harrington et al 1989, Chase and Ullrich 1990a, Otrosina et al 1993. Briefly, the North American S group infects several coniferous tree genera (e.g.…”

Section: Heterobasidion Annosum Species Complexmentioning

confidence: 99%

Ecological impacts of Phlebiopsis gigantea biocontrol treatment against Heterobasidion spp. as revealed by fungal community profiling and population analyses

Vainio¹

2008

Diss. For.

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Wood decay fungi belonging to the species complex Heterobasidion annosum sensu lato are among the most common and economically important species causing root rot and stem decay in conifers of the northern temperate regions. New infections by these pathogens can be suppressed by tree stump treatments using chemical or biological control agents. In Finland, the corticiaceous fungus Phlebiopsis gigantea h a s b e e n f o r m u l a t e d i n t o a commercial biocontrol agent called Rotstop (Verdera Ltd.).This thesis addresses the ecological impacts of Rotstop biocontrol treatment on the mycoflora of conifer stumps. Locally, fungal communities within Rotstop-treated and untreated stumps were analyzed using a novel method based on DGGE profiling of small subunit ribosomal DNA fragments amplified directly from wood samples. Population analyses for P. gigantea and H. annosum s.l. were conducted to evaluate possible risks associated with local and/or global distribution of the Rotstop strain.Based on molecular community profiling by DGGE, we detected a few individual wood-inhabiting fungal species (OTUs) that seemed to have suffered or benefited from the Rotstop biocontrol treatment. The DGGE analyses also revealed fungal diversity not retrieved by cultivation and some fungal sequence types untypical for decomposing conifer wood. However, statistical analysis of DGGE community profiles obtained from Rotstoptreated and untreated conifer stumps revealed that the Rotstop treatment had not caused a statistically significant reduction in the species diversity of wood-inhabiting fungi within our experimental forest plots.Locally, ISSR genotyping of cultured P. gigantea strains showed that the Rotstop biocontrol strain was capable of surviving up to six years within treated Norway spruce stumps, while in Scots pine stumps it was sooner replaced by successor fungal species. In addition, the spread of resident P. gigantea strains into Rotstop-treated forest stands seemed effective in preventing the formation of genetically monomorphic populations in the short run. On a global scale, we detected a considerable level of genetic differentiation between the interfertile European and North American populations of P. gigantea. These results strongly suggest that local biocontrol strains should be used in order to prevent global spread of P. gigantea and hybrid formation between geographically isolated populations.The population analysis for H. annosum s.l. revealed a collection of Chinese fungal strains that showed a high degree of laboratory fertility with three different allopatric H. annosum s.l. taxa. However, based on the molecular markers, the Chinese strains could be clearly affiliated with the H. parviporum taxonomical cluster, which thus appears to have a continuous distribution range from Europe through southern Siberia to northern China.

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Population structure of Heterobasidion annosum from North America and Europe

Cited by 72 publications

References 26 publications

Ecological Constraints Limit the Fitness of Fungal Hybrids in the Heterobasidion annosum Species Complex

Ecological Constraints Limit the Fitness of Fungal Hybrids in the Heterobasidion annosum Species Complex

Genetic Structure of Heterobasidion annosum in White Fir Mortality Centers in California

Ecological impacts of Phlebiopsis gigantea biocontrol treatment against Heterobasidion spp. as revealed by fungal community profiling and population analyses

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