Ericaceae (the heath family) are widely distributed calcifuges inhabiting soils with inherently poor nutrient status. Ericaceae overcome nutrient limitation through symbiosis with ericoid mycorrhizal (ErM) fungi that mobilize nutrients complexed in recalcitrant organic matter. At present, recognized ErM fungi include a narrow taxonomic range within the Ascomycota, and the Sebacinales, basal Hymenomycetes with unclamped hyphae and imperforate parenthesomes. Here we describe a novel type of basidiomycetous ErM symbiosis, termed 'sheathed ericoid mycorrhiza', discovered in two habitats in mid-Norway as a co-dominant mycorrhizal symbiosis in Vaccinium spp. The basidiomycete forming sheathed ErM possesses clamped hyphae with perforate parenthesomes, produces 1- to 3-layer sheaths around terminal parts of hair roots and colonizes their rhizodermis intracellularly forming hyphal coils typical for ErM symbiosis. Two basidiomycetous isolates were obtained from sheathed ErM and molecular and phylogenetic tools were used to determine their identity; they were also examined for the ability to form sheathed ErM and lignocellulolytic potential. Surprisingly, ITS rDNA of both conspecific isolates failed to amplify with the most commonly used primer pairs, including ITS1 and ITS1F + ITS4. Phylogenetic analysis of nuclear LSU, SSU and 5.8S rDNA indicates that the basidiomycete occupies a long branch residing in the proximity of Trechisporales and Hymenochaetales, but lacks a clear sequence relationship (>90% similarity) to fungi currently placed in these orders. The basidiomycete formed the characteristic sheathed ErM symbiosis and enhanced growth of Vaccinium spp. in vitro, and degraded a recalcitrant aromatic substrate that was left unaltered by common ErM ascomycetes. Our findings provide coherent evidence that this hitherto undescribed basidiomycete forms a morphologically distinct ErM symbiosis that may occur at significant levels under natural conditions, yet remain undetected when subject to amplification by 'universal' primers. The lignocellulolytic assay suggests the basidiomycete may confer host adaptations distinct from those provisioned by the so far investigated ascomycetous ErM fungi.

Department of Mycorrhizal Symbioses Institute of Botany Academy of Sciences of the Czech Republic Průhonice Czech Republic

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Read DJ. The biology of mycorrhiza in the Ericales. Can J Bot. 1983;61:985–1004.

Kron KA, Judd WS, Stevens PF, Crayn DM, Anderberg AA, et al. Phylogenetic classification of Ericaceae: Molecular and morphological evidence. Bot Rev. 2002;68:335–423.

Read DJ. The structure and function of the ericoid mycorrhizal root. Ann Bot-London. 1996;77:365–374.

Smith SE, Read DJ. Mycorrhizal Symbiosis. London, UK: Academic Press. 804 pp. 2008.

Massicotte HB, Melville LH, Peterson RL. Structural characteristics of root-fungal interactions for five ericaceous species in eastern Canada. Can J Bot. 2005;83:1057–1064.

Rains KC, Nadkarni NM, Bledsoe CS. Epiphytic and terrestrial mycorrhizas in a lower montane Costa Rican cloud forest. Mycorrhiza. 2003;13:257–264. PubMed

Setaro S, Weiss M, Oberwinkler F, Kottke I. Sebacinales form ectendomycorrhizas with Cavendishia nobilis, a member of the Andean clade of Ericaceae, in the mountain rain forest of southern Ecuador. New Phytol. 2006;169:355–365. PubMed

Rayner MC. Obligate symbiosis in Calluna vulgaris. Ann Bot-London. 1915;29:97–134.

Ternetz C. Űber die Assimilation des atmosphärischen Stickstoffes durch Pilze. Jahrbücher für wissenschaftliche Botanik. 1907;44:353–408.

Pearson V, Read D. Biology of mycorrhiza in the Ericaceae. I. The isolation of the endophyte and synthesis of mycorrhizas in aseptic culture. New Phytol. 1973;72:371–379.

Pearson V, Read D. Biology of mycorrhiza in the Ericaceae. II. Transport of carbon and phosphorus by endophyte and mycorrhiza. New Phytol. 1973;72:1325–1331.

Bonfante-Fasolo P. Occurrence of a basidiomycete in living cells of mycorrhizal hair roots of Calluna vulgaris. Trans Brit Mycol Soc. 1980;75:320–325.

Mueller WC, Tessier BJ, Englander L. Immunocytochemical detection of fungi in the roots of Rhododendron. Can J Bot. 1986;64:718–723.

Peterson TA, Mueller WC, Englander L. Anatomy and ultrastructure of a Rhododendron root-fungus association. Can J Bot. 1980;58:2421–2433.

Seviour RJ, Willing RR, Chilvers GA. Basidiocarps associated with ericoid mycorrhizas. New Phytol. 1973;72:381–385.

Gimingham CH. Biological flora of the British Isles: Calluna. J Ecol. 1960;48:455–483.

Englander L, Hull RJ. Reciprocal transfer of nutrients between ericaceous plants and a Clavaria sp. New Phytol. 1980;84:661–667.

Leake JR, Read DJ. Norris JR, Read DJ, Varma AK, editors. Experiments with ericoid mycorrhiza. 1991. Methods in Microbiology Vol. 23. London, UK: Academic Press, p 435–459.

Berch SM, Allen TR, Berbee ML. Molecular detection, community structure and phylogeny of ericoid mycorrhizal fungi. Plant Soil. 2002;244:55–66.

Allen TR, Millar T, Berch SM, Berbee ML. Culturing and direct DNA extraction find different fungi from the same ericoid mycorrhizal roots. New Phytol. 2003;160:255–272. PubMed

Bougoure DS, Parkin PI, Cairney JWG, Alexander IJ, Anderson IC. Diversity of fungi in hair roots of Ericaceae varies along a vegetation gradient. Mol Ecol. 2007;16:4624–4636. PubMed

Ishida TA, Nordin A. No evidence that nitrogen enrichment affect fungal communities of Vaccinium roots in two contrasting boreal forest types. Soil Biol Biochem. 2010;42:234–243.

Selosse MA, Setaro S, Glatard F, Richard F, Urcelay C, et al. Sebacinales are common mycorrhizal associates of Ericaceae. New Phytol. 2007;174:864–87. PubMed

Walker JF, Aldrich-Wolfe L, Riffel A, Barbare H, Simpson NB, et al. Diverse Helotiales associated with the roots of three species of Arctic Ericaceae provide no evidence for host specificity. New Phytol. 2011;191:515–527. PubMed

Zhang C, Yin LJ, Dai SL. Diversity of root-associated fungal endophytes in Rhododendron fortunei in subtropical forests of China. Mycorrhiza. 2009;19:417–423. PubMed

Kjøller R, Olsrud M, Michelsen A. Co-existing ericaceous plant species in a subarctic mire community share fungal root endophytes. Fungal Ecol. 2010;3:205–214.

Tedersoo L, Partel K, Jairus T, Gates G, Poldmaa K, et al. Ascomycetes associated with ectomycorrhizas: molecular diversity and ecology with particular reference to the Helotiales. Environ Microb. 2009;11:3166–3178. PubMed

Rice AV, Currah RS. Schulz BJE, Boyle CJC, Sieber TN, editors. Oidiodendron maius: Saprobe in Sphagnum peat, mutualist in ericaceous roots? 2006. Microbial root endophytes. Heidelberg, Germany: Springer, p 227–246.

Rice AV, Currah RS. Schulz BJE, Boyle CJC, Sieber TN, editors. Oidiodendron maius: Saprobe in Sphagnum peat, mutualist in ericaceous roots? 2006. Microbial root endophytes. Heidelberg, Germany: Springer, p 227–246.

Bajwa R, Abuarghub S, Read DJ. The biology of mycorrhiza in the Ericaceae X. The biology of mycorrhiza in the Ericaceae 10. The utilization of proteins and the production of proteolytic-enzymes by the mycorrhizal endophyte and by mycorrhizal plants. New Phytol. 1985;101:469–486. PubMed

Kerley SJ, Read DJ. The biology of mycorrhiza in the Ericaceae. XVIII. Chitin degradation by Hymenoscyphus ericae and transfer of chitin-nitrogen to the host plant. New Phytol. 1995;131:369–375. PubMed

Kerley SJ, Read DJ. The biology of mycorrhiza in the Ericaceae. XIX. Fungal mycelium as a nitrogen source for the ericoid mycorrhizal fungus Hymenoscyphus ericae and its host plant. New Phytol. 1997;136:691–701. PubMed

Kerley SJ, Read DJ. The biology of mycorrhiza in the Ericaceae. XX. Plant and mycorrhizal necromass as nitrogenous substrates for ericoid mycorrhizal fungus Hymenoscyphus ericae and its host. New Phytol. 1998;139:353–360. PubMed

Vohník M, Burdíková Z, Albrechtová J, Vosátka M. Testate amoebae (Arcellinida and Euglyphida) vs. ericoid mycorrhizal and DSE fungi: a possible novel interaction in the mycorrhizosphere of ericaceous plants? Microb Ecol. 2009;57:203–214. PubMed

Perotto S, Girlanda M, Martino E. Ericoid mycorrhizal fungi: some new perspectives on old acquaintances. Plant Soil. 2002;244:41–53.

Vrålstad T. Are ericoid and ectomycorrhizal fungi part of a common guild? New Phytologist. 2004;164:7–10. PubMed

Bödeker ITM, Nygren CMR, Taylor AFS, Olson A, Lindahl BD. Class II peroxidase-encoding genes are present in a phylogenetically wide range of ectomycorrhizal fungi. ISME Journal. 2009;3:1387–1395. PubMed

Pazourková Z. Botanická mikrotechnika. Prague, Czech Republic: Charles University Press. 1986.

Gardes M, Bruns TD. ITS primers with enhanced specificity for basidiomycetes - application to the identification of mycorrhizae and rusts. Mol Ecol. 1993;2:113–118. PubMed

White TJ, Bruns TD, Lee SB, Taylor JW. Innis N, Gelfand D, Sninsky J, White T, editors. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. 1990. PCR – protocols and applications – a laboratory manual. New York, USA: Academic Press, p 315–322.

Martin KJ, Rygiewicz PT. Fungal-specific PCR primers developed for analysis of the ITS region of environmental DNA extracts. BMC Microbiol. 2005;5:28–38. PubMed PMC

Tedersoo L, Koljalg U, Hallenberg N, Larsson KH. Fine scale distribution of ectomycorrhizal fungi and roots across substrate layers including coarse woody debris in a mixed forest. New Phytologist. 2003;159:153–165. PubMed

O’Donnell K. Reynolds DR, Taylor JW, editors. Fusarium and its near relatives. 1993. The fungal holomorph: mitotic, meiotic and pleomorphic speciation in fungal systematics. Wallingford, UK: CAB International, p 225–233.

Nováková A, Hubka V, Saiz-Jimenez C, Kolařík M. Aspergillus baeticus sp. nov. and Aspergillus thesauricus sp. nov.: two new species in section Usti originating from Spanish caves. Int J Syst Evol Microbiol ijs.0.041004-0; published ahead of print April 13, 2012, 2012. doi: 10.1099/ijs.0.041004-0. PubMed

Matheny PB, Wang Z, Binder M, Curtis JM, Lim YW, et al. Contributions of rpb2 and tef1 to the phylogeny of mushrooms and allies (Basidiomycota, Fungi). Mol Phylogenet Evol. 2007;43:430–451. PubMed

Hall TA. BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucl Ac Sym Ser. 1999;41:95–98.

Garcia-Sandoval R, Wang Z, Binder M, Hibbett DS. Molecular phylogenetics of the Gloeophyllales and relative ages of clades of Agaricomycotina producing a brown rot. Mycologia. 2011;103:510–524. PubMed

Binder M, Larsson KH, Matheny PB, Hibbett DS. Amylocorticiales ord. nov. and Jaapiales ord. nov.: Early diverging clades of Agaricomycetidae dominated by corticioid forms. Mycologia. 2010;102:865–880. PubMed

Talavera G, Castresana J. Improvement of phylogenies after removing divergent and ambiguously aligned blocks from protein sequence alignments. Syst Biol. 2007;56:564–577. PubMed

Guindon S, Dufayard JF, Lefort V, Anisimova M, Hordijk W, et al. New algorithms and methods to estimate maximum-likelihood phylogenies: assessing the performance of PhyML 3.0. Syst Biol. 2010;59:307–321. PubMed

Stamatakis A, Hoover P, Rougemont J. A fast bootstrapping algorithm for the RAxML web-servers. Syst Biol. 2008;57:758–771. PubMed

Ronquist F, Huelsenbeck JP. MrBayes 3: Bayesian phylogenetic inference under mixed models. Bioinformatics. 2003;19:1572–1574. PubMed

Rambaut A, Drummond AJ. Tracer v1.4, Available from. 2007. http://beast.bio.ed.ac.uk/Tracer.In.

Guindon S, Gascuel O. A simple, fast, and accurate algorithm to estimate large phylogenies by maximum likelihood. Syst Biol. 2003;52:696–704. PubMed

Posada D. jModelTest: phylogenetic model averaging. Mol Biol Evol. 2008;25:1253–1256. PubMed

Hambleton S, Sigler L. Meliniomyces, a new anamorph genus for root-associated fungi with phylogenetic affinities to Rhizoscyphus ericae (Hymenoscyphus ericae), Leotiomycetes. Stud Mycol. 2005;53:1–27.

Xiao G, Berch SM. Ericoid mycorrhizal fungi of Gaultheria shallon. Mycologia. 1992;84:470–471.

Mrnka L, Tokarová H, Vosátka M, Matějka P. Interaction of soil filamentous fungi affects needle composition and nutrition of Norway spruce seedlings. Trees-Struct Funct. 2009;23:887–897.

Thorn RG. The use of cellulose azure agar as a crude assay of both cellulolytic and ligninolytic abilities of wood-inhabiting fungi. P Jpn Acad B-Phys. 1993;69:29–34.

Palfner G. Agerer R, editor. Descolea antarctica. 1998. editor. Colour atlas of ectomycorrhizae. Schwäbisch Gmünd, Germany: Einhorn-Verlag, Plate 116.

Larsson KH. Molecular phylogeny of Hyphoderma and the reinstatement of Peniophorella. Mycol Res. 2007;111:186–195. PubMed

Binder M, Hibbett DS, Larsson KH, Larsson E, Langer E, et al. The phylogenetic distribution of resupinate forms across the major clades of mushroom-forming fungi (Homobasidiomycetes). Syst Biodivers. 2005;3:113–157.

Matheny PB, Gossmann JA, Zalar P, Kumar TKA, Hibbett DS. Resolving the phylogenetic position of the Wallemiomycetes: an enigmatic major lineage of Basidiomycota. Can J Bot. 2006;84:1794–1805.

Vohník M, Albrechtová J. The co-occurrence and morphological continuum between ericoid mycorrhiza and dark septate endophytes in roots of six European Rhododendron species. Folia Geobot. 2011;46:373–386.

Arora DS, Sandhu DK. Laccase production and wood degradation by Trametes hirsuta. Folia Microbiol. 1984;29:310–315.

Vohník M, Fendrych M, Albrechtová J, Vosátka M. Intracellular colonization of Rhododendron and Vaccinium roots by Cenococcum geophilum, Geomyces pannorum and Meliniomyces variabilis. Folia Microbiol. 2007;52:407–414. PubMed

Kemp BM, Smith DG. Use of bleach to eliminate contaminating DNA from the surface of bones and teeth. Forensic Sci Int. 2005;154:53–61. PubMed

Deslippe JR, Simard SW. Below-ground carbon transfer among Betula nana may increase with warming in Arctic tundra. New Phytol. 2011;192:689–698. PubMed

Kohout P, Sýkorová Z, Bahram M, Hadincová V, Albrechtová J, et al. Ericaceous dwarf shrubs affect ectomycorrhizal fungal community of the invasive Pinus strobus and native Pinus sylvestris in a pot experiment. Mycorrhiza. 2011;21:403–412. PubMed

Robertson SJ, Rutherford PM, Massicotte HB. Plant and soil properties determine microbial community structure of shared Pinus-Vaccinium rhizospheres in petroleum hydrocarbon contaminated forest soils. Plant Soil. 2011;346:121–132.

Withington JM, Reich PB, Oleksyn J, Eissenstat DM. Comparisons of structure and life span in roots and leaves among temperate trees. Ecol Monogr. 2006;76:381–397.

Read DJ, Perez-Moreno J. Mycorrhizas and nutrient cycling in ecosystems – a journey towards relevance? New Phytol. 2003;157:475–492. PubMed

Bending G, Read DJ. Lignin and soluble phenolic degradation by ectomycorrhizal and ericoid mycorrhizal fungi. Mycol Res. 1997;101:1348–1354.

Vohník M, Sadowsky JJ, Lukešová T, Albrechtová J, Vosátka M. Inoculation with wood decomposing basidiomycete, but not with root symbiotic ascomycetes, positively affects growth of highbush blueberry (Ericaceae) grown in a pine litter substrate. Plant Soil. 2012;355:341–352.

Burke RM, Cairney JWG. Carbohydrate oxidases in ericoid and ectomycorrhizal fungi: a possible source of Fenton radicals during the degradation of lignocellulose. New Phytol. 1998;39:637–645.

Casieri L, Anastasi A, Prigione V, Varese GC. Survey of ectomycorrhizal, litter-degrading, and wood-degrading Basidiomycetes for dye decolorization and ligninolytic enzyme activity. Anton Leeuw Int J G. 2010;98:483–504. PubMed

Bougoure DS, Cairney JWG. Assemblages of ericoid mycorrhizal and other root-associated fungi from Epacris pulchella (Ericaceae) as determined by culturing and direct DNA extraction from roots. Environ Microb. 2005;7:819–827. PubMed

Rosling A, Cox F, Cruz-Martinez K, Ihrmark K, Grelet GA, et al. Archaeorhizomycetes: unearthing an ancient class of ubiquitous soil fungi. Science. 2011;333:876–879. PubMed

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