Relative abundance and potential dispersal range of intersterility groups of <i>Heterobasidion annosum</i> in pure and mixed forests

Gonthier, Paolo; Garbelotto, Matteo; Varese, Giovanna Cristina; Nicolotti, G.

doi:10.1139/b01-090

Cited by 48 publications

(68 citation statements)

References 29 publications

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“…From several Heterobasidion isolates collected in the Lazio region (central Italy) and already screened for identification by mitochondrial DNA analysis (Gonthier et al 2001), five H. annosum and five H. irregulare heterokaryons were chosen for a growth test on agar medium and for an inoculation test on pine seedlings (Table 1). They were also characterized by sequence analyses of the nucleic gene of the elongation factor 1-α and the mitochondrial gene of the ATP synthase subunit 6 (Johannesson and Stenlid 2003;Kretzer and Bruns 1999).…”

Section: Isolatesmentioning

confidence: 99%

Behaviour of Heterobasidion annosum and Heterobasidion irregulare isolates from central Italy in inoculated Pinus pinea seedlings

2010

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Five Heterobasidion annosum and five H. irregulare isolates, collected in central Italy, were tested in order to assess the differences in their behaviour, on PDA medium and in two inoculation experiments on three-yearold Pinus pinea seedlings. In vitro the average growth rate of H. irregulare isolates was faster than H. annosum isolates at a temperature ranging between 5 to 30°C. In an inoculation test, performed at a temperature between 8 and 12°C, all the isolates had a comparable growth in the seedlings after three weeks, but successful infection was significantly more frequent with the H. irregulare isolates. Inoculation was repeated with only two individual isolates, collected from within the National Park of Circeo in disease centres that were very close to each other. This test was performed at a higher temperature (8-24°C), and observations were carried out one, two, three and six weeks later. The H. irregulare isolate always produced a more extended infection in seedlings than the H. annosum isolate. The study indicates that H. irregulare has a somewhat different behaviour versus P. pinea in comparison with H. annosum. We thus believe that the need to monitor how this situation evolves should not be overlooked.

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Section: Isolatesmentioning

confidence: 99%

Behaviour of Heterobasidion annosum and Heterobasidion irregulare isolates from central Italy in inoculated Pinus pinea seedlings

2010

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“…After 3 weeks, a small piece of mycelium was taken from the side of each of the two isolates and transferred into a new petri dish, resulting in hybrids with identical nuclear genomes but one with a mitochondrial genome of H. abietinum and the other with a mitochondrial genome of H. parviporum. The hybrid nature of the isolates was revealed by the presence of clamp connections in the mycelia, and mitochondrial characterization was done using a taxon-specific competitive-priming PCR technique as previously described (21). Inoculum and inoculation techniques were as described for experiment one.…”

Section: Inoculation Studies (I) Experiments Onementioning

confidence: 99%

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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“…Bref. Samples were incubated for at least 10 days in moist conditions at about 24°C and examined for the presence of the pathogen by using a dissecting microscope (ϫ20 magnification), as described by Gonthier et al (2001).…”

Section: Phytosanitary Surveys and Analysesmentioning

confidence: 99%

Further observations on sudden diebacks of Scots pine in the European Alps

Gonthier¹,

Giordano²,

Nicolotti³

2010

The Forestry Chronicle

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Since the beginning of the 1990s, significant mortality of Scots pine trees has been observed in inner valleys of the Alps. The objectives of this work were to investigate and describe the aetiology of a Scots pine dieback in the Aosta Valley (western Italian Alps) in 2005. Surveys were conducted in three forest stands. Crown transparency was assessed to evaluate the incidence and severity of dieback symptoms. Phytosanitary surveys were also performed. The time series of the major climatic parameters was analyzed in order to identify common climatic anomalies between the dieback of 2005 and similar dieback episodes in other periods and in other areas of the western Alps. Dendrochronological analyses were performed to assess the relationship between tree-ring widths and climatic parameters. The lack of primary biotic agents and the low frequency of secondary pathogens suggest an abiotic origin of diebacks. The time series analysis shows that two consecutive years with a value of summer dryness index below 1.5 preceded the diebacks. Tree-ring width and summer dryness index were strongly and significantly associated.

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Relative abundance and potential dispersal range of intersterility groups of Heterobasidion annosum in pure and mixed forests

Cited by 48 publications

References 29 publications

Behaviour of Heterobasidion annosum and Heterobasidion irregulare isolates from central Italy in inoculated Pinus pinea seedlings

Behaviour of Heterobasidion annosum and Heterobasidion irregulare isolates from central Italy in inoculated Pinus pinea seedlings

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

Further observations on sudden diebacks of Scots pine in the European Alps

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