Spatial distribution of discrete RAPD phenotypes of a root endophytic fungus, Phialocephala fortinii, at a primary successional site on a glacier forefront

Abstract

Phialocephala fortinii is among the few identified hyphomycetes belonging to the Mycelium radicis atrovirens complex. This ' dark-septate endophyte ' has a global distribution and colonizes a wide variety of host plants. In this study, the spatial distribution of discrete genets of P. fortinii on the forefront of a receding glacier was analysed using the randomly amplified polymorphic DNA (RAPD) technique to determine plants colonized and patterns of colonization. In two consecutive years of sampling, a total of 74 isolates of P. fortinii were obtained from nine plant species, typically ectomycorrhizal, ericoid mycorrhizal or non-mycorrhizal. The isolates showed substantial variation, sharing on average approx. half the RAPD markers. In the first year, three isolates belonging to a single genet were obtained from two plants separated by a distance of nearly 1n5 m. The continuity of this genet was assessed by a sampling the following year. No isolates similar to that, or any of the genets collected the year before were observed. Consequently, the identical isolates from the previous year were concluded to represent discontinuous ramets. Two additional large genets were observed during the second year of sampling, which inhabited roots of several plants representing three different species. These data suggest that the sharing of P. fortinii genets among plant species might play a fundamental role in adaptation and interaction within the whole plant community in a system undergoing primary succession.

The effect of experimental warming on the root-associated fungal community of Salix arctica

“…Since roots were washed well before characterization, the root-associated fungal community should be dominated by mycorrhizal fungi, dark septate endophytes, hyaline septate endophytes, and possibly root-pathogens. Ectomycorrhizal and ericoid mycorrhizal fungi are important components of arctic systems (Gardes and Dahlberg, 1996), and dark septate endophytes and hyaline septate endophytes are ubiquitous in both alpine and arctic systems (Bledsoe et al, 1990;Gardes and Dahlberg, 1996;Jumpponen, 1999;Cázares et al, 2005). Although the contributions of mycorrhizas to nutrient uptake are well-known (Smith and Read, 1997), the function of dark septate endophytes and hyaline septate endophytes are less clear, as they appear to range from pathogenic to mutualistic (Jumpponen, 2001).…”

Piceirhiza bicolorata– the ectomycorrhizal expression of the Hymenoscyphus ericae aggregate?

“…Several studies have shown that the dark septate endophyte P. fortinii, one of the most abundant associate taxa of the Mycelium radicis atrovirens complex (Melin, 1921 ;Ahlich & Sieber, 1996 ;, colonizes a wide variety of ectomycorrhizal, ericoid and non-mycorrhizal host plants (Haselwandter & Read, 1982 ;Stoyke & Currah, 1991 ;Jumpponen, 1999). The ' mycorrhizal ' status of P. fortinii is not yet settled, but it has been shown to exhibit some typical mycorrhizal responses with Salix glauca (Fernando & Currah, 1996) and Pinus contorta .…”

A new dawn – the ecological genetics of mycorrhizal fungi

“…By scoring the presence and absence of bands across strains as dominant markers, the authors could distinguish individuals (genets) and analyze population genetic structure. Similar techniques have recently been used to measure the clone sizes of ECM fungi in several studies (Bonello et al, 1998 ;Gherbi et al, 1999 ;Jumpponen, 1999). However, the present study is one of the first to relate genetic structure to an ecological influence such as habitat variation.…”