Mycorrhizal capacity of wood-decay fungi

Transcription

1 Mycorrhizal capacity of wood-decay fungi A. Menkis and R. Vasaitis Department of Forest Mycology and Plant Pathology Swedish University of Agricultural Sciences, P.O. Bo 7026, SE Uppsala, Sweden

2 Content Fungal lifestyles Evolutionary instability of fungal lifestyles Laboratory study: colonisation of fine living roots by wood-decay fungi Morphology Anatomy Function Field study: colonisation of fine living roots and rhizosphere soil by wooddecay fungi Conclusions Future prospects

3 Fungal lifestyles Biotrophic ectomycorrhizal fungi depend on the host trees for transfer of photosynthesis products Saprotrophic wood-decay fungi feed on dead wood by wood decomposition

4 Evolutionary instability of fungal lifestyles Pluteus petasatus Entoloma strictius Phylogeny and ancestral state reconstructions ancestry in free-living saprotrophs many gains and losses in mycorrhizal and saprotrophic fungi evolutionary instability and dynamic of fungal lifestyles intermediate state? Russula compacta Auriscalpium pyidata Hibbett et al Red = mycorrhizal Black = non-mycorrhizal

5 Fungi in mycorrhizal roots of nursery seedlings Menkis et al. 2005

6 Laboratory study Colonisation of fine living roots of tree seedlings by wood-decay fungi The aim: to eamine the ability of saprotrophic wood-decay fungi to colonise and functionally interact with fine living roots of tree seedlings and to determine the effect of those interactions on health of the plants

7 Hypothesis Saprotrophic wood-decay fungi may colonise and functionally interact with living tree roots and may form the saprotrophy biotrophy continuum

8 Eperimental design 200 species of wood-decay fungi Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) seedlings Three replicates 1200 fungus-plant microcosm systems P. sylvestris P. abies

9 Assessed Microcosms were monitored during si months period, and patterns of roots colonisation by wood-decay fungi and health status of the plants were recorded Morphology of colonised roots was eamined using dissection microscopy Anatomy of colonised roots was eamined using differential staining of root sections and light microscopy Microcosms with observed colonisation of roots by wood-decay fungi were selected to assess fungus plant functional interaction using 14 C radioactive tracer

10 Patterns of fine root colonisation by wood-decay fungi P. sylvestris Armillaria mellea P. sylvestris H. parviporum P. abies - Phlebiopsis gigantea P. sylvestris - Hypholoma capnoides P. sylvestris - Coniophora cerebella P. sylvestris - Lenzites betulina

11 Fungal species Pinus sylvestris Picea abies Microcosms with observed root colonisation by wood-decay fungi Smith et al. submitted manuscript Amylostereum ferreum Amylostereum laevigatum Armillaria cepistipes Armillaria mellea Bjerkandera adusta Ceratobasidium sp.257 Chondrostereum purpureum Collybia butyracea Collybia sp.9 Coniophora cerebella Creolophus cirrhatus Fomes fomentarius Grifola frondosa Gymnopus sp.406 Heterobasidion parviporum Hypholoma capnoides Hypholoma fasciculare Lenzites betulina Marasmius androsaceus Mycena epipterygia Mycena sp.480 Mycena sp.915 Osmoporus odoratus Phellinus chrysoloma Phellinus sp.323 Phellinus tremulae Phlebia centrifuga Pholiota gummosa Pholiota squarrosa Phlebiopsis gigantea Pleurotus ostreatus Polyporus suaveolens Schizophyllum commune Stereum sanguinolentum Trametes hirsuta

12 Results Si months after microcosm establishment, 96% of plants remained healthy-looking while the growth substrate was abundantly colonised by the fungal mycelia Seedling decline and mortality was rare 4% (e.g. in microcosms inoculated with Phanerochaete, Kuehneromyces, Hymenochaete) In 16.5% of pine and 5.5% of spruce microcosms, fine living roots were colonised by wood-decay fungi The most distinct pattern of root colonisation was in P. abies - Phlebiopsis gigantea system

13 Morphology of colonised roots Root colonised by ectomycorrhizal fungus Suillus luteus Root colonised by wood-decay fungus Phlebiopsis gigantea Vasiliauskas et al. 2007

14 Photo by JM Plett Anatomy of colonised roots Section of fine root colonised by ectomycorrhizal fungus Laccaria bicolor Section of fine root colonised by wood-decay fungus Phlebiopsis gigantea

15 Functional interactions: transfer of 14 C in P. sylvestris - P. gigantea microcosm system Shoot 48h after labelling with 14 CO 2 Radioactive 14 C is accumulated at the tips of actively growing roots Radioactive 14 C is transported to the fungal mycelia via colonised roots

16 Role of secondary metabolites produced by Phlebiopsis gigantea New natural product isolated from Rotstop strain of Phlebiopsis gigantea Terfestatin A inhibits the epression of auin-inducable genes and physiological auin responses in roots of Arabidopsis Broberg et al. unpublished

17 Field study Colonisation of fine living roots and rhizosphere soil by wood-decay fungi The aims: to assess the etent of root colonisation of P. gigantea and other wood-decay fungi under the field conditions to determine the effect of Rotstop biocontrol agent of P. gigantea treatment on its establishment and persistence in the tree roots and soil Menkis et al. 2012

18 Hypothesis Rotstop biocontrol agent of Phlebiopsis gigantea may colonise living tree roots and rhizosphere soil and compete with resident fungal species for the same ecological niches

19 Study sites Countries: Finland and Latvia Forests: boreal and north temperate Sites: 17 P. gigantea stump treatment and control sites

20 Forest environment Clear-cut Thinning Study sites represented 1-60 months-old clear-cuts and thinned forest sites

21 Sampling in the field Root systems of understory trees (1-5 per site) were sampled in vicinity ( 0.5m) to the stumps Three soil cores were sampled in each site in vicinity ( 0.5m) to the stumps

22 Sample preparation Roots Soil Humus layer Mineral layer Sieving Freeze drying DNA isolation, amplification and 454-sequencing

23 No. of taa Data collected 454-sequencing of ITS rdna resulted in high-quality sequences representing: Fungi % Protista - 3.1% Plants - 0.4% Animals - 0.1% Assembly of fungal sequences resulted in 456 contigs (at the 97% similarity level representing different fungal taa) of which 42.5% were singletons and 57.5% were non-singletons Fine roots Humus Mineral soil Richness estimator (chao1) predicted that the maimum number of taa could be higher by ca % No. of sequences

24 Taonomic identification Identification at least to genus level was successful for 172 (37.7%) out of 456 of potential fungal taa, representing 69.1% of all fungal sequences Distribution of fungal sequences Mucoromycotina 8% Basidiomycetes 44% Ascomycetes 48%

25 Most common taa Taon Reference sequence Identity (%) No. of sequences Proportion Piloderma sphaerosporum UDB /354 (99) Phialocephala fortinii HM /301 (99) Oidiodendron sp. AF /298 (95) Piloderma sp. UDB /333 (95) Tylospora fibrillosa UDB /350 (98) Tomentella sp. UDB /377 (96) Unidentified Mucoromycotina HQ /355 (94) Cryptococcus terricola FN /390 (99) Unidentified Mucoromycotina HQ /361 (99) Unidentified Ascomycota HM /305 (98) Cryptococcus podzolicus FR /317 (99) Meliniomyces sp. FN /304 (95) Ceratocystis sp. DQ /314 (99) Unidentified Ascomycota EU /303 (94) Unidentified Ascomycota FJ /301 (98) Lactarius tabidus UDB /414 (99) Unidentified Ascomycota FR /301 (93) Tomentella sublilacina UDB /217 (98) Mycena galopus HM /366 (99) Cenococcum geophilum EU /303 (98) Phlebiopsis gigantea AF /363 (99) Mortierella humilis AJ /395 (99) Tomentella stuposa UDB /362 (97)

26 Site Forest operation P. gigantea in different substrates Time since forest operation (months) Substrate Fine roots Humus soil Mineral soil Finland H1-Control Clear-cut a a 0.00 a 1.99 H2 Clear-cut a 0.41 b 6.41 a 1.87 H3 Clear-cut a 2.17 ab 1.00 a 0.57 H4 Clear-cut a 3.17 b 2.83 a 1.76 H5 Clear-cut a 2.22 b 0.00 a 0.49 All Finland Latvia G9 Thinning b 0.00 a 0.00 G2-Control Thinning b 1.01 a 0.37 G1 Thinning a 7.14 ab b 6.93 G3 Thinning a 0.00 b 0.00 a 0.00 G4 Thinning a 0.00 b a 0.34 G5-Control Thinning a 0.00 b b 3.60 G6 Thinning a 1.82 ab 0.58 a 0.50 G10 Thinning a 0.00 b ab 2.85 G8-Control Thinning a 0.00 ab a 0.94 G7 Clear-cut ab 0.00 a 0.00 G11 Clear-cut a 2.14 ab 2.68 a 1.48 G12-Control Clear-cut a 0.00 b 0.60 a 0.18 All Latvia All sites Total

27 Other wood-decay fungi Taa Substrate Total Fine roots Humus Mineral soil Clitopilus sp Ganoderma lipsiense Heterobasidion annosum Mycena galopus Mycena pura Mycena spp Phlebia sp Phlebiella christiansenii Resinicium bicolor All

28 Conclusions Wood-decay fungi were capable to colonise living tree roots in vitro and in situ, but such associations were rare Majority of wood-decay fungi tested under the laboratory conditions had little or no effect on health of the plants P. gigantea living tree root association structurally and functionally resembled closely mycorrhizal symbiosis Stump treatment with P. gigantea had no significant effect on occurrence and relative abundance of this species in tree roots and soil

29 Future prospects Is transportation of nutrients from wood-decay fungi to the plant? What is the role of terfestatin-like and other novel molecules of P. gigantea in fungus living tree root symbiosis? What is the role of wood-decay fungi in the soil? Insights from genomes of wood-decay fungi: how species have evolved, what are the genes involved in symbiosis, their function, regulation and evolution?

30 Thank you