Resinicium Bicolor Research Articles

Fungal Diversity in Multiple Post-harvest Aged Red Pine Stumps and Their Potential Influence on Heterobasidion Root Rot in Managed Stands Across Minnesota.

Thinning operations that occur in managed red pine (Pinus resinosa) stands, create tree stumps that can serve as a habitat for fungi, especially Heterobasidion irregulare, the cause of a serious root disease. Different fungi can colonize stumps early and the community of fungi can change over time as initial fungal species become replaced. Samples were collected from both the native and non-native range of red pine from stumps that were cut at different time periods. Stumps that were harvested at 0-1, 2-3, 5-6, and 10-12 years before sampling were used to provide data on the diversity of fungi that colonize tree stumps and how these communities can change over time as well as how they influence colonization of H. irregulare. Traditional culturing methods and Illumina MiSeq sequencing were used to identify the fungi in the samples. Of particular interest was Phlebiopsis gigantea, which can colonize cut stumps and prevent H. irregulare from becoming established. Overall, P. gigantea was the most abundant fungus isolated and sequenced via Illumina MiSeq. Results show that Phlebiopsis gigantea was isolated from 90% of all stumps sampled for sites harvested within 3 years of sampling in the native range of red pine compared to 33% in the non-native range. For Illumina MiSeq, 5,940 total amplicon sequence variants (ASVs) were detected. P. gigantea represented 14% of the total reads and composed 19% of the reads in the native range and 8% in non-native range of red pine. Furthermore, P. gigantea represented 38% of the reads for stumps that were harvested within 3 years of sampling in the native range of red pine compared to 14% in the non-native range. These results help demonstrate that a higher amount of P. gigantea is present in the native range of red pine and could be acting as a native biological control agent. Additional fungi, including Resinicium bicolor, Hypochnicium cremicolor, Leptographium spp., and others identified at different cutting times are also discussed. Finally, different diversity indices revealed similar, but slightly higher diversity for southern sites via Shannon and Simpson Diversity indices. Beta diversity demonstrated a similar species composition in stumps harvested at different times with these stumps being grouped together based on harvesting years.

A new technique to estimate percentage decolorization of synthetic dyes on solid media by extracellular laccase from white-rot fungus

The enormous colored effluent discharges due to increased usage of synthetic dyes in textile and other chemical industries pollute both freshwater and marine reservoirs and cause ecotoxicity and serious health problems. This issue needs to be addressed skillfully and demands an ecofriendly and economically feasible technique. Pertaining to this, the current study was focused on the use of a white rot fungus, Resinicium bicolor to decolorize and degrade a recalcitrant dye, Congo red (CR) through its extracellular laccase enzyme secreted by mycelia. This work was also intended to develop a simple mathematical formula to calculate decolorization (%) of various dye categories usually tested on the solid medium plate involving different white rot fungi. The fungus was grown on malt extract agar (MEA) plate containing media supplemented with CR, 1% (g/l) to check the extent of decolorization and hence efficacy of Resinicium bicolor laccase at an interval of 24 hours (hrs). Decolorization (%) was determined by a formula derived from ‘Plate Volume Method’ (PVM). The maximum decolorization achieved on solid medium was 97.79% and 96.79% in liquid culture medium by the end of 96 hrs without the involvement of any chemical mediators which are generally toxic and expensive. Efficient decolorization achieved in the liquid medium validated the accuracy of ‘PVM’.

Dynamics of fungal communities during Gastrodia elata growth

BackgroundGastrodia elata is a widely distributed achlorophyllous orchid and is highly valued as both medicine and food. Gastrodia elata produces dust-like seeds and relies on mycorrhizal fungi for its germination and growth. In its life cycle, G. elata is considered to switch from a specific single-fungus relationship (Mycena) to another single-fungus relationship (Armillaria). However, no studies have investigated the changes in the plant-fungus relationship during the growth of G. elata in the wild. In this study, high-throughput sequencing was used to characterize the fungal community of tubers in different growth phases as well as the soils surrounding G. elata.ResultsThe predominant fungi were Basidiomycota (60.44%) and Ascomycota (26.40%), which exhibited changes in abundance and diversity with the growth phases of G. elata. Diverse basidiomycetes in protocorms (phase P) were Hyphodontia, Sistotrema, Tricholoma, Mingxiaea, Russula, and Mycena, but the community changed from a large proportion of Resinicium bicolor (40%) in rice-like tubers (phase M) to an unidentified Agaricales operational taxonomic unit 1(OTU1,98.45%) in propagation vegetation tubers (phase B). The soil fungi primarily included Simocybe, Psathyrella, Conocybe, and Subulicystidium. Three Mycena OTUs obtained in this study were differentially distributed among the growth phases of G. elata, accounting for less than 1.0% of the total reads, and were phylogenetically close to Mycena epipterygia and M. alexandri.ConclusionsOur data indicated that G. elata interacts with a broad range of fungi beyond the Mycena genus. These fungi changed with the growth phases of G. elata. In addition, these data suggested that the development of the fungal community during the growth of G. elata was more complex than previously assumed and that at least two different fungi could be involved in development before the arrival of Armillaria.

Fungal communities in Norway spruce stumps along a latitudinal gradient in Sweden

Tree stumps left after clear-cutting have replaced naturally formed logs as the most common type of coarse woody debris in managed boreal forests. It is therefore necessary to understand stump importance for the biodiversity of wood-inhabiting organisms, including fungi, and determine their role in hosting species of conservation interest. We analyzed wood from 485 Norway spruce (Picea abies) stumps from 41 clear-cuts at seven localities along a latitudinal gradient from northern to southern Sweden using 454-sequencing. We also collated data about the known ecology of the 86 identified macro-basidiomycetes. In total, 1355 fungal operational taxonomic units were detected, of which 19% were identified down to genus or species level. The most widespread fungi were generalists, such as Leptodontidium elatius, Resinicium bicolor, Fomitopsis pinicola, and Coniophora puteana. Five species of conservation interest were detected, but were not abundant (Kneiffiella curvispora, Metulodontia nivea, Perenniporia subacida, Postia placenta, and Climacocystis borealis). Fungal community composition changed with stump age and along the latitudinal gradient.These results will enable us to better incorporate important biodiversity and conservation issues when making decisions about using stumps as resources for biofuel.

Bioremediation Potentials of <i>Heterobasidion annosum</i> 13.12B and <i>Resinicium bicolor</i> in Diesel Oil Contaminated Soil Microcosms

The remediation potentials of diesel oil by two white rot fungi ( Basidiomycota; Hymenomycetes ) Heterobasidion annosum 13.12B and Resinicium bicolor were tested in two artificially contaminated experimental matrices: Norkran’s liquid medium and Insch - Pitcaple soil collected from Aberdeen, United Kingdom. Gravimetric measurements showed reductions in the weight of the hydrocarbon extract from soil inoculated with H. annosum 13.12B and R. bicolor . The reduction in diesel extract was observed to be higher in the treatments with H. annosum 13.12B compare with other treatments in soil microcosm amended with 3.5 and 7 % diesel oil. Significant increase in extractable hydrocarbon was detected in Norkran’s liquid medium amended with 1 and 3.5 % diesel oil. These results showed that white rot fungi could be harnessed to remediate soil contaminated with diesel oil in the field. Keywords : bioremediation, diesel oil, Heterobasidion annosum, Resinicium bicolor , pollution, gravimetric measurement

Armillaria novae‐zelandiae and other basidiomycete wood decay fungi in New Zealand Pinus radiata thinning stumps

SummaryTwo studies were undertaken in a young New Zealand Pinus radiata stand to find a biological control agent for armillaria root disease caused by Armillaria novae‐zelandiae. Fresh thinning stumps were inoculated with saprophytic basidiomycete species as wooden dowel cultures or as homogenized aqueous mycelial suspensions, while all stumps were also inoculated with dowel cultures of A. novae‐zelandiae. After a period of between one and two years, no differences were found among test fungi in the percentage of Armillaria species isolated from stumps. However, inoculation of Stereum sanguinolentum as homogenate, and of Phlebiopsis gigantea, Sistotrema brinkmannii, Hypholoma acutum and Rigidoporus concrescens as dowel cultures, significantly increased their isolation incidence in comparison with stumps not treated by these species. Phlebiopsis gigantea, Resinicium bicolor and R. concrescens were also isolated with greater frequency nearer to their dowel inoculation points. Results suggest that P. gigantea and S. sanguinolentum should be included in further testing. However, a future trial is likely to be more effective if evaluation is directed towards the portion of the stump below the soil surface, particularly the root system.

Contrasting Effects of Elevated Temperature and Invertebrate Grazing Regulate Multispecies Interactions between Decomposer Fungi

Predicting the influence of biotic and abiotic factors on species interactions and ecosystem processes is among the primary aims of community ecologists. The composition of saprotrophic fungal communities is a consequence of competitive mycelial interactions, and a major determinant of woodland decomposition and nutrient cycling rates. Elevation of atmospheric temperature is predicted to drive changes in fungal community development. Top-down regulation of mycelial growth is an important determinant of, and moderator of temperature-driven changes to, two-species interaction outcomes. This study explores the interactive effects of a 4 °C temperature increase and soil invertebrate (collembola or woodlice) grazing on multispecies interactions between cord-forming basidiomycete fungi emerging from colonised beech (Fagus sylvatica) wood blocks. The fungal dominance hierarchy at ambient temperature (16 °C; Phanerochaete velutina > Resinicium bicolor > Hypholoma fasciculare) was altered by elevated temperature (20 °C; R. bicolor > P. velutina > H. fasciculare) in ungrazed systems. Warming promoted the competitive ability of the fungal species (R. bicolor) that was preferentially grazed by all invertebrate species. As a consequence, grazing prevented the effect of temperature on fungal community development and maintained a multispecies assemblage. Decomposition of fungal-colonised wood was stimulated by warming, with implications for increased CO2 efflux from woodland soil. Analogous to aboveground plant communities, increasing complexity of biotic and abiotic interactions appears to be important in buffering climate change effects on soil decomposers.

Outcomes of fungal interactions are determined by soil invertebrate grazers

Saprotrophic fungal community composition, determined by the outcome of competitive mycelial interactions, is one of the many key factors affecting soil nutrient mineralisation and decomposition rates. Fungal communities are not generally predicted to be regulated by top-down factors, such as predation, but rather by bottom-up factors, including resource availability. We show that invertebrate grazers can exert selective pressures on fungal decomposer communities in soil, reversing the outcomes of competitive interactions. By feeding selectively on the cord-forming fungus Resinicium bicolor, isopods prevented the competitive exclusion of Hypholoma fasciculare and Phanerochaete velutina in soil and wood. Nematode populations also reversed the outcomes of competitive interactions by stimulating growth of less competitive fungi. These represent two opposing mechanisms by which soil fauna may influence fungal community composition and diversity. Factors affecting soil invertebrate communities will have direct consequences for fungal-mediated nutrient cycling in woodland soils.

Initial fungal colonizer affects mass loss and fungal community development in Picea abies logs 6yr after inoculation

Picea abies logs were inoculated with Resinicium bicolor, Fomitopsis pinicola or left un-inoculated and placed in an old-growth boreal forest. Mass loss and fungal community data were collected after 6 yr to test whether simplification of the fungal community via inoculation affects mass loss and fungal community development. Three techniques were used to survey communities: (1) observation of fruiting structures; (2) culturing on media; and (3) cloning and sequencing of ITS rDNA. Fruit body surveys detected the smallest number of species (18, 3.8 per log), DNA-based methods detected the most species (72, 31.7 per log), and culturing detected an intermediate number (23, 7.2 per log). Initial colonizer affected community development and inoculation with F. pinicola led to significantly greater mass loss. Relationships among fungal community composition, community richness and mass loss are complex and further work is needed to determine whether simplification of fungal communities affects carbon sequestration in forests.

Species-specific effects of grazing invertebrates on mycelial emergence and growth from woody resources into soil

Extensive studies on the grazing of young basidiomycete mycelial systems by invertebrates have revealed effects on extension rate, hyphal coverage and fractal geometry. To date, no studies have compared the grazing effects of different invertebrates on the ability of fungi to emerge from wood and establish mycelial systems in soil. Here, the effects of six soil invertebrate taxa on mycelial emergence and subsequent development of six basidiomycetes were compared. Woodlouse (Oniscus asellus), millipede (Blaniulus guttulatus), oribatid mite (Euzetes globulus), collembola (Folsomia candida), enchytraeid (Enchytraeus crypticus) and nematode (Panagrellus redivivus) populations were allowed to graze Phanerochaete velutina, Resinicium bicolor, Phallus impudicus and three different isolates of Hypholoma fasciculare mycelia as they emerged from beech (Fagus sylvatica) wood-inocula in 2-dimensional soil-tray microcosms. Impacts varied between invertebrate taxa, ranging from woodlice which affected mycelial development of all fungal isolates and completely prevented mycelial growth in two fungal species, to mites and enchytraeids which had no discernable effect on any of the fungi. Grazing impacts also varied between and within fungal species. Wood decay rates were affected with implications for nutrient mineralisation and decomposition.

Invertebrate grazing determines enzyme production by basidiomycete fungi

Extracellular enzymes produced by heterotrophic microorganisms in the soil are responsible for the decomposition of organic compounds. Basidiomycete fungi are the primary decomposer agents in temperate wooded ecosystems and contribute extensively to extracellular enzyme activity and nutrient mineralisation within soils. Growth and development of basidiomycete mycelia is influenced by soil-dwelling invertebrate grazers with potential implications for fungal activity and ecosystem functioning. The impacts of four invertebrate taxa belonging to Isopoda, Myriapoda, Collembola and Nematoda on the production of eight hydrolytic enzymes by four saprotrophic basidiomycetes ( Phanerochaete velutina, Resinicium bicolor and two strains of Hypholoma fasciculare) were compared in a factorial microcosm study. Grazing generally increased enzyme production but invertebrates had species-specific impacts on enzyme activity. The magnitude of grazing influenced enzyme activity; macrofauna (woodlice and millipedes) induced the greatest responses. Enzymatic responses varied markedly between fungi. Grazing enhanced enzyme activity in the exploitative mycelial networks of P. velutina and H. fasciculare, while the opposite effects were observed in the explorative R. bicolor networks. The impacts of soil fauna on nutrient mineralisation depend on fungal community composition. β-glucosidase, cellobiohydrolase, N-acetylglucosaminidase, acid phosphatase and phosphodiesterase activities were affected most frequently by grazing and invertebrate activity, and thus had direct consequences for carbon, nitrogen and phosphorous cycling. The results indicate that invertebrate diversity and community composition may influence the spatial distribution and activity of extracellular enzymes with direct implications for nutrient mineralisation and trunover in woodland soils.

Decay fungi in decomposing postharvest <i>Pinus radiata</i> root and branch debris

Knowledge of fungal populations decomposing Pinus radiata debris following harvesting may reveal a basidiomycete able to compete with pathogenic Armillaria species or help explain variation in decomposition rates Decay fungi were isolated after 2 or 3 years from buried root segments and branch segments placed on the soil surface at six sites in New Zealand A large variety of decay fungi was obtained different species being isolated at each site as well as from branch versus root segments Communities of decay fungi were more diverse in branches (one species per 101 segments) than root debris (one species per 553 segments) At the same site species tended to differ between spatially separated replicates for branch but not root segments For root segments identical fungi were frequently obtained at different depths in the same replicate This implies that branch segments were colonised separately by airborne spores whereas root segments were exposed to mycelial growth through the soil Few fungi were identified but three Resinicium bicolor Sistotrema sp and Stereum sanguinolentum are common in P radiata woody debris

Grazing by collembola affects the outcome of interspecific mycelial interactions of cord-forming basidiomycetes

While there is a plethora of studies on the effects of invertebrate grazing on mycelia, including several studies on saprotrophic cord-forming basidiomycetes, there is little information on the effects of grazing on mycelial interactions. The study compares the progress and outcomes of interspecific mycelial interactions between Hypholoma fasciculare, Phallus impudicus, Phanaerochaete velutina and Resinicium bicolor when grazed by the collembola Folsomia candida or Protaphorura armata in agar culture and trays (24 × 24 cm) of non-sterile soil. In ungrazed systems results were broadly consistent with previous studies, though there were few instances of deadlock, and a clear transitive (A > B > C) hierarchy could not be discerned. Instead, there was an intransitive hierarchy (i.e., A > B, B > C but C > A). Additionally, in agar culture, there were considerable differences in combative ability of four different strains of H. fasciculare. Collembola grazing had major effects on mycelial interactions. F. candida grazing altered both the outcome and progression of half of the fungal interactions studied, while the less active P. armata had almost no discernable effects on fungal interactions. Grazing by F. candida affected mycelial extension rate in five of the interaction combinations, some increasing, others decreasing. In grazed systems of P. velutina interacting with H. fasciculare, extension rate of the former was much more rapid over the opponent than over soil. Not only did grazing affect mycelial interactions, but interactions affected grazer activity; H. fasciculare was grazed in areas where it was interacting with P. velutina mycelium, but less so elsewhere. By altering the outcome of mycelial interactions and mycelial extension rate, collembola grazing may alter the distribution of cord-forming fungi on the forest floor, and may also play a role in maintaining the diversity of fungal species. The differences in combative ability of different strains of a species imply an even more complex scenario in the natural world.

Non‐trophic effects of oribatid mites on cord‐forming basidiomycetes in soil microcosms

1. Saprotrophic cord‐forming basidiomycetes are the primary agents of decomposition in forest ecosystems. Collembola and oribatid mites affect fungal growth and foraging, and therefore decomposition, through direct mycelial grazing.2. Grazing on the fungal species Hypholoma fasciculare, Resinicium bicolor and Phanerochaete velutina by the collembola Folsomia candida, and the oribatid mites Steganacarus magnus, Euzetes globulus and Hermannia gibba was investigated in soil microcosms.3. Folsomia candida grazed on all fungal species: radial extent of R. bicolor, hyphal coverage of all fungal species, and fractal dimension of R. bicolor and P. velutina were all reduced. Oribatid mites did not graze the fungi but did affect mycelial morphology. Steganacarus magnus caused a reduction in the radial extent of H. fasciculare, and the hyphal coverage and fractal dimension in both H. fasciculare and R. bicolor. Euzetes globulus and H. gibba reduced the hyphal coverage of P. velutina.4. Oribatid mites are associated with a cornucopia of chemical secretions with possible anti‐fungal properties. Chemical analysis of H. gibba opisthonotal secretions revealed four main compounds, all of which are new to the known spectrum of opisthonotal components. The most abundant was (E)‐β‐farnesene.5. Treatment effects were species‐specific in terms of both fungal and invertebrate species. This study provides the first evidence of non‐grazing effects of oribatid mites on fungal growth and morphology. This could potentially influence the spatial organisation of mycelium in forest soils and therefore the ability of fungi to locate, colonise and decompose dead organic matter.

Collembola foraging responses to interacting fungi

Abstract 1. Temperate woodland Collembola feed predominantly on plant detritus and fungi. They exhibit preferences for different fungi reflecting resource value in terms of Collembola growth and reproduction.2. Studies of fungal grazing by Collembola have focused on non‐interacting fungi and have used one genetic isolate as representative of an entire fungal species. This study examines the effects of fungal interactions on Collembola behaviour, and elucidates differences arising from the use of genetically distinct fungal isolates.3. Folsomia candida were added to microcosms in which paired combinations of the fungi, Hypholoma fasciculare (four isolates), Phallus impudicus, Phanerochetae velutina and Resinicium bicolor (two isolates), were interacting. Collembola movement and mortality was recorded for 26 days. A constant preference for one fungal mycelium over the other was shown by Collembola in 12 of the 36 interactions studied. Lowest Collembola mortality was normally recorded on the preferred mycelium.4. In 11 of the remaining 24 interactions, Collembola preference switched from one mycelium to the other; the greatest number of dead Collembola was recorded on the final preference.5. Collembola behaviour on different fungal isolates was broadly similar, although in one species’ combination a change in fungal isolate resulted in a total reversal of Collembola preference. The implications of these results for decomposer food webs are considered.

Impact of white-rot fungi on numbers and community composition of bacteria colonizing beech wood from forest soil

White-rot fungi are important wood-decomposing organisms in forest ecosystems. Their ability to colonize and decompose woody resources may be strongly influenced by wood-inhabiting bacteria that grow on easily utilizable compounds e.g. oligomers of wood-polymers released by fungal enzymes. However, so far, it is not known how white-rot fungi deal with the presence of potential competing bacteria. Here, the effects of two white-rot fungi, Hypholoma fasciculare and Resinicium bicolor, on the numbers and composition of bacteria colonizing sterile beech wood blocks from forest soil are reported. Both total numbers (microscopic counts) and the numbers of cultivable wood-inhabiting bacteria were considerably lower in wood blocks that became colonized by the white-rot fungi than in control blocks. This points to the fungi out-competing the opportunistic bacteria. The presence of white-rot fungi resulted in a change in the relative abundance of families of cultivable bacteria in wood and also in a change of denaturing gradient gel electrophoresis patterns of directly amplified 16S rRNA gene fragments. Analysis of the bacterial community structure in soil adhering to exploratory mycelium (cords) indicated that fungal species-specific effects on bacterial community composition were also apparent in this fungal growth phase.

Species-specific impacts of collembola grazing on fungal foraging ecology

Fungi are primary agents of organic matter decomposition in forests. Although invertebrate grazing affects fungal biomass and morphology, the species-specific consequences of these interactions are little understood. Using three collembola species ( Folsomia candida, Protaphorura armata, Proisotoma minuta) we employed a multi-trophic approach to investigate the individual effects of invertebrate grazing on four species of saprotrophic basidiomycete fungi growing in two species (one fungus: one collembola) soil microcosms. We studied these effects at three trophic levels: the rate of wood decay brought about by the fungi was assessed; fungal growth was characterized across multiple time points using a range of image analysis parameters (radial extension, hyphal coverage, fractal dimension); and collembola abundance was determined at the end of the experiment. Collembola species had different impacts both within and across fungal species; F. candida had the greatest effect on fungal mycelia whereas P. armata often had little impact. Fungal species varied in their resilience to grazing; all collembola species modified Phanerochaete velutina and Hypholoma fasciculare morphology, that of Resinicium bicolor was only markedly affected by F. candida, and effects on Phallus impudicus were negligible. In the case of H. fasciculare, these grazing effects translated into effects on the rate of fungus-induced wood decay: F. candida and P. armata, but not P. minuta, reduced wood decay rate compared to ungrazed controls. Rate of wood decay was unaffected in the other three fungal species. Changes in collembola population size were generally consistent across fungal species, with each species achieving a greater abundance on P. velutina than on H. fasciculare and P. impudicus. The collembola species did, however, respond differently to R. bicolor, with F. candida being more successful than P. armata. Our study suggests that a wide range of impacts can occur during fungus–collembola interactions, and that caution should be exercised when treating saprotrophic fungi and mycophagous collembola as uniform functional components.

Morphological and molecular studies on Resinicium s. str.

Resinicium Parmasto is typified by Resinicium bicolor (Alb. & Schwein.: Fr.) Parm., (Hymenochaetales, Basidiomycota), a readily recognized and widely distributed corticioid, lignicolous species in the northern hemisphere. Five new species of Resinicium closely allied to R. bicolor from the Caribbean region are described and illustrated: Resinicium confertum Nakasone, sp. nov., Resinicium monticola Nakasone, sp. nov., Resinicium mutabile Nakasone, sp. nov., Resinicium rimulosum Nakasone, sp. nov., and Resinicium tenue Nakasone, sp. nov. In addition, R. bicolor and Resinicium friabile Hjortstam & Melo are redescribed and illustrated. Sequence analyses of the internal transcribed spacer region support the recognition of the new taxa. Further, nuclear small subunit ribosomal RNA sequence data support the recognition of two groups of Resinicium species: the Resinicium s. str. group, including R. bicolor, and the Resinicium s.l. group that includes Resinicium furfuraceum (Bres.) Parm. The genus Resinicium is redefined and a key to the Resinicium s. str. species is provided.

Changes in Volatile Production During the Course of Fungal Mycelial Interactions Between Hypholoma fasciculare and Resinicium bicolor

The mycelia of two wood decay basidiomycete fungi were grown opposing each other across a 1-microm pore membrane supported on the surface of malt broth, contained within a sealable reaction vessel. Production of volatiles during the time course of interaction was followed by collecting head space samples by solid phase microextraction (100 microm polydimethylsiloxane fiber) on five occasions over 25 d following coinoculation of the fungi: 1, 3 (i.e., immediately prior to mycelial contact), 9 (1-2 d after initiation of pigment production by Resinicium bicolor), 17, and 25 d. Ten volatiles were produced during interactions that were not detected in single species controls. In general, most (18) fungal volatiles were sesquiterpenes eluted between 12.5 and 21 min, with a further two eluted at 29.1 and 33.9 min; a benzoic acid methyl ester, a benzyl alcohol, and a quinolinium type compound with a distinctive fragmentation pattern at m/z 203, 204, 206, and 207 were also identified; three volatiles with m/z maxima of 163, 159, and 206-208, respectively, remained unidentified. The results are discussed in relation to possible ecological roles of volatiles.

Colonization of Sitka spruce stumps by decay-causing hymenomycetes in paired inoculations

Sitka spruce stumps were inoculated with decay fungi using colonized sawdust or dowel inoculum to investigate colonization in paired combinations. Estimates of domain sizes were made in the top 15 cm of stump after 13–14 or 21–23 months with sawdust or dowel inoculations, respectively. None of the co-inoculated species prevented colonization by Heterobasidion annosum; sapwood colonization by Resinicium bicolor may limit growth of H. annosum colonies out of heartwood, reducing the incidence of disease transfer at root contacts. H. annosum colonized stumps despite the presence of competing inoculum. Reduced colonization occurred in paired inoculations with R. bicolor, but not with other fungi. Co-inoculations with Stereum sanguinolentum increased colonization by H. annosum. R. bicolor largely remained in the upper 3–4 cm of stumps and reduced colonization by Melanotus proteus; growth of S. sanguinolentum was completely prevented. The results are discussed in relation to the colonization strategies of the decay fungi, their ability to colonize stumps in the presence of competitors and factors influencing development of communities of decay fungi in stumps.