A COMPARATIVE ANALYSIS OF THE CULTURED MICROMYCETES IN OLIGOTROPHIC PEATLANDS OF NATURAL BIOSPHERE RESERVATIONS LOCATED IN THE NORTHERN AND CENTRAL PARTS OF RUSSIA

The current study addresses the fungal diversity of the peatlands that vary geographically and geologically, in the central and northern parts of Russia. The central (Smolenskaya area, National Park «Smolenskoye Poozerie») and northern (White Sea Biological Station area) peatlands have a different geological history, the former have a glacial origin, while the latter are of marine origin. Our aim was to investigate the fungal biota of these zones full of Sphagnum moss, and possibly reveal the species that are pertinent to these particular habitats. In both investigated areas, we found an overall poor species diversity with a high fraction of sterile mycelia. Many penicillia species were dominating in all peat samples – P. thomii, P. spinulosum, P. glabrum, P. funiculosum, P. aurantiogriseum (together with Geotrichum candidum), many of them are known to degrade Sphagnum. We were particularly interested in the dynamics of the species from the genus Oidiodendron that have been shown to be involved in primary Sphagnum degradation. The northern area contained a larger species diversity of Oidiodendron, as compared to the central zone. Interestingly, insect-associated species of the genus Tolypocladium and Beauveria, along with the psychrotolerant species of Geomyces and Tolypocladium were recovered only from the northern peatlands. Aspergillus spp. were found in peatlands of the central zone only. We link this result to the climatic features of the area, but also different invertebrate contents that may be utilized by fungi. We detected a tendency of an increasing diversity of Oidiodendron species, psychrotolerant and entomopathogenic fungal species as well as a proportion of sterile forms in the northern area.

Oligotrophic peatlands cover more than 10% of Russia's territory and are the largest reservoirs of peat among peatland types in Russia (Yurkovskaya, 2004).Although oligotrophic peatlands are prevalent in northern areas such as taiga and tundra zones, they also occur more southerly, to the extent of the steppe zone.The peat accumulation is caused by microorganisms that decompose organic matter at a relatively slow rate.The slow rate is corroborated by extremely unfavourable abiotic conditions: low oxygen, low temperature, low pH, high humidity and presence of inhibitory phenolic compounds from a local vegetation, mostly Sphagnum mosses.Specific groups of fungi and bacteria are the main players involved in the process of organic matter decomposition in peat (Kachalkin et al., 2005;Gilbert, Mitchell, 2006;Thormann, Rice, 2007;Andersen et al., 2010;Golovchenko et al., 2013).However, the diversity of fungi inhabiting oligotrophic peatland remains understudied, especially in the northern regions.The comparison of the fungal biota between oligotrophic peatlands of both central and northern areas would allow to evaluate the fungal species that are shared (or different) among habitats, possibly shedding some light on their physiology in peat.Existing studies suggest that the fungal diversity among oligotrophic peatlands may vary significantly (Thormann et al., 2004;Thormann, Rice, 2007).The reason is believed to be the unique associations of fungi with specific plants, which are pertinent to a given area (Nilsson et al., 1992;Thormann et al., 2004;Filippova, 2015).

Material and Methods
We have been monitoring fungi at the White Sea coastal and Smolensk region peatlands for a number of years now.Using various approaches, we sought to recover most of the culturable fungal species from that area (Bilanenko, Grum-Grzhimaylo, 2007;Grum-Grzhimaylo et al., 2010, 2012, 2016).Since

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the Sphagnum mosses are the main ingredient of peat, we collected and analyzed the samples from the vertical columns of peat deposits where dominated by Sphagnum spp.Hence, our comparative analysis of the fungal biota in differently located oligotrophic peats was accounting for the climatic factors (mainly temperature) rather than plant-associated differences of fungal communities.The pH values of the samples in both regions were similar and varied from 4.0 to 4.5.Climatic factors globally affect the distribution of biota, including one of the most prominent inhabitants of the oligotrophic peats -an arctic mosquito (Aedes spp., Culex spp.).During warm season, these species reproduce in bulk, and along with the plant material, can act as a food source for fungi (Bubnova et al., 2014).Our research attempts to compare fungal diversity of the two distinct following types of peatlands -the White Sea coastal peatlands (White Sea Biological Station, WSBS, northern, 66°34ʹ N, 33°08ʹ E) and the Smolensk region peatlands (National Park «Smolenskoye Poozerie», SP, central, 55°53ʹ N, 31°40ʹ E) (Fig. ).The first type appears to have been formed as a result of a part of the sea becoming isolated in the course of a land uplift, followed by both demineralization and bogging (Shaporenko et al., 2005;Pantyulin, Krasnova, 2011), whereas the central type shows boggy depressions of glacial origin (Smolensk LakeLand…, 2016).The comparison of the fungal biota between the two boggy areas may give us a clue about the shared species, but also unique ones that may contribute to local ecology of a given peatland.
The climate of the SP is moderately continental with well-defined seasons.Wet air masses from the Atlantic release frosts and snowfalls in winter and a high temperature and rain in summer.The average yearly temperature here is about 4.3 о С (National Park…, 2016).The climate of the WSBS region is transitional from marine polar to moderately continental.There are long winter and spring, short summer and long autumn at the WSBS.The average yearly temperature here is about 0.5 о С (Shilovtseva, 2009).In June 2006 29 and 25 peat samples from three SP peatlands were taken and from three WSBS peatlands in June 2007, subsequently.The detailed description of the peatlands and taking, storing and cultivation of the samples has been exposed in our earlier works (Bilanenko, Grum-Grzhimaylo, 2007;Grum-Grzhimaylo et al., 2016).Only the differences in the methods are remarked here.The peat samples from the SP were stored at deep freeze until the cultivation, whereas the samples from the WSBS

Results and Discussion
Our results indicate that the explored peatlands of both regions show low species diversity of the cultured micromycetes.The analysis of the SP samples helped to identify 39 species of fungi and to reveal 3 sterile isolates.The samples of the WSBS peatlands contained 31 species and 8 sterile mycelia.Only 8 fungal species were found in both regions (sterile isolates excluded) (Table ).It is known that specific conditions of peatlands restrict the diversity of fungi (Grum-Grzhimaylo, Bilanenko, 2010).
The prevailing number of anamorphic species belonged to Ascomycota, mostly Penicillium spp.These results do not disprove the existing view on the mycobiota of peatlands (Thormann, Rice, 2007).The following species were found in both regions: P. thomii, P. spinulosum, P. glabrum, P. funiculosum, P. aurantiogriseum.The capacity of P. spinulosum and P. thomii to decompose Sphagnum was mentioned in a number of earlier mycological works (Chastuchin, 1967;Dickinson, Maggs, 1974).P. spinulosum is regarded as a typical species for a humus soil horizon and oligotrophic peatlands (Summerbell, 2005).This species is widely spread in the soils of tundra and taiga and in bogs of various types.P. spinulosum is capable to grow in a wide range of temperatures (from 5 о C to 42 о C).The upper layers of peatlands, including the peatlands of temperate zones, are characterized by drastic changes in temperature regime.P. thomii is capable to develop in the temperature range of 5-37 о C. It is found in all complexes of filamentous fungi isolated from acidic soils, in peatlands and from bog plants (Domsh et al., 2007).P. glabrum is a common species in podsolic and other acidic soils, raised bogs and fens.P. glabrum is widely spread in northern regions, including the soils of the Arctic tundra (Nilsson et al., 1992;Domsh et al., 2007).In our research this species was found in two WSBS peatlands and in one SP peatland.The cosmopolitan species P. funiculosum (Talaromyces funiculosus) was among the dominating species in all SP peatlands (frequency of occurrence was up to 20-30% and the colony-forming units (CFU) value up to 10 4 CFU per 1 gram of a dry sample).P. funiculosum was found in all WSBS peatlands and dominated in one of them (frequency of occurrence up to 100%, CFU value up to 10 6 CFU per 1 gram of a dry sample).P. funiculosum can grow in a broad temperature range (5-42 о C).This species survives in extremely cold and acidic conditions, in low oxygen conditions (Domsh et al., 2007;Grum-Grzhimaylo, 2013).It can be found in all types of soils, in oligotrophic peatlands and in taiga marsh soils.P. funiculosum is capable to destroy Sphagnum mosses (Dickinson, Maggs, 1974;Thormann et al., 2004;Thormann, Rice, 2007).
We found Geotrichum candidum (Diplodascus geotrichum) in both peatland systems mentioned in this work.This fungus is also known as a destructor of Sphagnum mosses (Dickinson, Maggs, 1974;Karunen, Kalviainen, 1985).It can exist in highly moist conditions (Dix, Webster, 1995).In further research we managed to isolate it in all WSBS peatlands samples we explored.
Oidiodendron species are known as primary destructors of Sphagnum mosses (Tsuneda et al., 2001).Oidiodendron spp.grow at acidic and even extremely acidic conditions (pH-values from 1.5 to 6.0) (Gross, Robbins, 2000;Domsh et al., 2007).In our research O. griseum and O. periconioides were found in northern peatlands, O. cereale was found in peatlands of the central zone.O. griseum was one of the dominant species in WSBS peatlands.O. griseum is a typical species of the ericales rhizosphere, peat and podsolic soils.O. periconioides and O. cereale are also known as typical species for Sphagnum bogs (Thormann, Rice, 2007).In frost peatlands of the Kola Peninsula we discovered even greater Oidiodendron species diversity than in WSBS peatlands (our unpublished data).
The psychrotolerant species Geomyces pannorum (Pseudogymnoascus pannorum) was identified in WSBS samples with high frequency and abundance.However, it was not revealed in SP samples at all.G. pannorum is a psychrotolerant species and it can be found predominantly in northern soils of tundra and in conditions of the natural cryopreservation (Tosi et al., 2002;Kochkina et al., 2007).This species is known as polyextremotolerant, capable to develop under the influence of numerous stress factors such as low temperature, low water activity and lack of oxygen.This allowed it to survive in anaerobic conditions, which are common for cryopegs in permafrost (Kochkina et al., 2007;Shcherbakova et al., 2010).G. pannorum can grow in a wide range of pH values (3.5-8.0)(van Oorschot, 1980).This species was isolated in large quantities (CFU value up to 10 5 for 1 gram of a dry sample) at the depth of 1 metre from a peat sample of a northern bog, which supports the conditions of low temperatures and low oxygen content.Psychrotolerant type of temperature adaptation is also common for Tolypocladium spp.(Bisset, 1982).Tolypocladium spp.were found in the WSBS samples, but not in the SP ones.
Tolypocladium spp.and Beauveria spp.(T.inflatum, T. geodes, B. bassiana) are known as associated with insects.These species were found in the northern peatlands only.This fact was also  A considerable share in fungi societies of both regions is represented by sterile mycelia.Their number is higher in northern regions.Using molecular methods we showed later that the majority of sterile forms are basidiomycetes (Grum-Grzhimaylo et al., 2016).
The fact is that the absence of some species in the samples could be explained by the low number of samples or by other methodological errors.For example, the absence of Trichoderma spp. in WSBS samples was quite surprising.In the following years we consistently discovered T. piluliferum, T. polysporum, T. harzianum, T. viride in WSBS peatlands.
We assume that the detected tendency of the increasing diversity and the abundance of Oidiodendron spp., psychrotolerant and entomopathogenic fungal species (Geomyces pannorum, Tolypocladium spp., Beauveria spp.) as well as the proportion of sterile forms in the northern area is clear.

Fig.
Fig. Map of both research locations.

Nature Conservation Research. Заповедная наука 2016. 1 (2): 90-95 demonstrated
(Grum-Grzhimaylo et al., 2016)aylo et al., 2016).One of the possible reasons for such abundance of Tolypocladium spp.andB. bassiana in the northern peatlands may be connected with considerable populations of invertebrates, including larvae of sanguivorous mosquitoes, on which these species can grow.Aspergillus spp.(A.fischeri, A. fumigatus, A. niger) known as typical in the southern regions were found in SP peatlands only.