Lactarius Rufus Research Articles

Fatty acid composition of various ectomycorrhizal fungi and ectomycorrhizas of Norway spruce

Whole cell fatty acid (WCFA) compositions of three different structures of ectomycorrhizal (ECM) fungi: sporocarps, pure culture mycelia and ectomycorrhizas were analysed to evaluate the potential use of fatty acid profiles as biomarkers for ECM fungi and ectomycorrhiza-associated bacteria. Sporocarps of Amanita muscaria, Amanita rubescens, Lactarius rufus, Lactarius thejogalus, Leccinum scabrum, Paxillus involutus, Russula foetens, Russula rosea, Russula vesca, Suillus grevillei, Tylopilus felleus, Xerocomus badius, Xerocomus subtomentosus, pure cultures of A. muscaria, P. involutus, X. badius, X. subtomentosus, Suillus bovinus Suillus luteus and seven ectomycorrhizal morphotypes of Norway spruce were examined. Our results revealed species-specific composition of fatty acids of fungal sporocarps and pure culture mycelia. Ectomycorrhizal morphotypes distinguished and identified by morphological and molecular methods (PCR-RLFP and sequencing) created specific fatty acid profiles. The dominating fatty acids in pure cultures and sporocarps were 18:2 ω6,9, 18:1 ω9 and 16:0, whereas ectomycorrhizas also contained plant and bacterial specific fatty acids. Especially, fatty acids specific to Gram-positive bacteria 15:0 anteiso and 17:0 anteiso were present in relatively high amounts and suggested that these bacteria are dominating in the examined Norway spruce mycorrhizosphere. In conclusion, our results show that fatty acid based methods can be useful in studies of ectomycorrhizal fungi, both as a quick method for differentiation of fungal species and also in studies of mycorrhiza-associated microorganisms in the field.

Mycorrhization helper bacteria: a case of specificity for altering ectomycorrhiza architecture but not ectomycorrhiza formation

Mycorrhization helper bacteria (MHB), isolated from phylogenetically distinct ectomycorrhizal symbioses involving Lactarius rufus, Laccaria bicolor or Suillus luteus, were tested for fungus specificity to enhance L. rufus-Pinus sylvestris or L. bicolor-P. sylvestris mycorrhiza formation. As MHB isolated from the L. rufus and S. luteus mycorrhiza were originally characterised using a microcosm system, we assessed their ability to enhance mycorrhiza formation in a glasshouse system in order to determine the extent to which MHB are system-specific. Paenibacillus sp. EJP73, an MHB for L. rufus in the microcosm, significantly enhanced L. bicolor mycorrhiza formation in the glasshouse, demonstrating that the MHB effect of this bacterium is neither fungus-specific nor limited to the original experimental system. Although the five MHB strains studied were unable to significantly enhance L. rufus mycorrhiza formation, two of them did have a significant effect on dichotomous short root branching by L. rufus. The effect was specific to Paenibacillus sp. EJP73 and Burkholderia sp. EJP67, the two strains isolated from L. rufus mycorrhiza, and was not associated with auxin production. Altered mycorrhiza architecture rather than absolute number of mycorrhizal roots may be an important previously overlooked parameter for defining MHB effects.

Does wood ash application increase heavy metal accumulation in forest berries and mushrooms?

A number of experiments have been established at the Finnish Forest Research Institute during the last few decades to study the effect of wood ash application on soil substrate, ground vegetation and stand growth on drained mires and mineral soil forests. In this study, the plots of 23 experiments were sampled to determine whether ash application significantly increases heavy metal accumulation in forest berries and mushrooms. Both short-term (between 2 months and 4 years) and long-term effects (between 10 and 52 years after application) were studied. The heavy metal concentrations (Al, Fe, Mn, Zn, Cr, Cu, Cd, As, Ni, Pb, Ti, V and Mo) were measured using ICP-AES. No significant increase in heavy metal accumulation in the cloudberry ( Rubus chamaemorus), cowberry ( Vaccinium vitis-idaea) and bog whortleberry ( Vaccinium uliginosum) or in the caps and stipes of russule ( Russula paludosa), rufous milk-cap ( Lactarius rufus), northern milk-cap ( Lactarius trivialis), velvet bolete ( Suillus variegatus) and in-rolled paxil ( Paxillus involutus) was usually observed. In contrast, in the older experiments (13–52 years), the concentrations were often lower than those in the controls, except for As. Cd concentrations in cloudberry, bog whortleberry, in-rolled paxil and rufous milk-cap occasionally decreased significantly. The results indicated that this ash-induced decrease in heavy metal accumulation may be a long-term effect. The concentrations of Al, Fe, As, Ni and Ti in the mushrooms were occasionally very high in the younger ash experiments (2–14 months after application); probably it was a case of surface contamination by heavy metal-rich ash residue, rather than active metal uptake. It was concluded that the heavy metals brought into the ecosystem by ash application are unlikely to be accumulated in any considerable amounts in forest berries and mushrooms.

Rufuslactone, a New Antifungal Sesquiterpene from the Fruiting Bodies of the Basidiomycete Lactarius rufus.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Effects of nitrogen with and without acidified sulphur on an ectomycorrhizal community in a Sitka spruce ( Picea sitchensis Bong. Carr) forest

This preliminary study investigated the effects of enhanced nitrogen (NH 4NO 3 at 48 kg ha −1 y −1), sulphur (Na 2SO 4 at 50 kg ha −1y −1), acidified nitrogen and sulphur (H 2SO 4 + NH 4NO 3) at pre-stated doses (pH 2.5), and acidified nitrogen and sulphur deposition at double these doses on the ectomycorrhizal community associated with a 13-year-old Sitka spruce ( Picea sitchensis) forest. Sulphur deposition had little impact on below ground ectomycorrhizal diversity, but stimulated sporocarp production. Nitrogen inputs increased below ground colonisation compared to acidified nitrogen and sulphur, largely due to an increase in Tylospora fibrillosa colonisation. Sporocarp production and ectomycorrhizal root colonisation by Lactarius rufus were reduced in the nitrogen treated plots. These observations suggest that nitrogen deposition to a young plantation may suppress ectomycorrhizal fungi producing large sporocarps. It is proposed that enhanced nitrogen deposition increases ectomycorrhizal nitrogen assimilation, consuming more carbon and leaving less for extrametrical mycelium and sporocarp development.

Rufuslactone, a New Antifungal Sesquiterpene from the Fruiting Bodies of the Basidiomycete Lactarius rufus

A new lactarane sesquiterpene, rufuslactone (1), was isolated from the fruiting bodies of the basidiomycete Lactarius rufus. Rufuslactone (1) is an isomer of a previously described lactarane 3,8-oxa-13-hydroxylactar-6-en-5-oic acid gamma-lactone (2) from Lactarius necatar. Its structure,was elucidated on the basis of spectroscopic data. Rufuslactone (1) showed antifungal properties against plant pathogenic fungi.

The mycorrhizal community in a forest chronosequence of Sitka spruce [Picea sitchensis (Bong.) Carr.] in Northern England

Demography and fungal diversity of the belowground ectomycorrhizal community in a chronosequence of Sitka spruce [Picea sitchensis (Bong.) Carr.] in Northumberland, Northern England, were analysed; mycorrhizal root samples were taken from 6-, 12-, 30- and 40-year-old stands, and fungal fruiting bodies were collected in autumn to complement the survey. Naturally germinated seedlings less than 1 year of age (taken from the 30-year-old stand) were also examined. A total of 118,000 mycorrhizal root tips were extracted from 40 soil cores (ten per age class) and from the complete root systems of 25 seedlings and separated into active and senescent root tips according to their morphology and anatomy. Active tips were distinguished according to their mycobionts which were characterised and identified microscopically. Although almost 100% of all fine roots were mycorrhizal, EM fungal diversity throughout the chronosequence was low, consisting of a total of 16 species of which three were only found as fruiting bodies. Of the six mycobionts found most regularly below ground, Tylospora fibrillosa was the most common, colonising about 70% of all root tips and more than 90% of those of seedlings and young trees. Root density and mycorrhizal diversity increased, but percentage of vital root tips decreased with increasing tree age, levelling off in the 30- and 40-year-old stand. Among the five subdominant fungal species, Dermocybe crocea was found to have its peak of distribution in the 12-year-old stand and Russula emetica, Lactarius rufus, Hymenoscyphus ericae agg. and the unidentified Piceirhiza sulfo-incrustata in the 30- and 40-year-old stands. The possible correlations between the mycorrhizal community structure and biotic and abiotic factors are discussed.

Effect of ectomycorrhizal fungi on nitrogen mineralisation and the growth of Scots pine seedlings in natural peat

The aim of this study was to investigate the potential of different isolates of ectomycorrhizal (EM) fungi to enhance the growth of Pinus sylvestris seedlings in five natural peat substrates with different nitrogen concentrations, and the effect of the Scots pine seedlings and fungal inoculum on the formation of dissolved inorganic and organic nitrogen in peat. Utilization of different organic nitrogen compounds by microbial community in the peat was also investigated using Biolog MT MicroPlates. Inoculation of the seedlings with EM fungi enhanced seedling growth. Piloderma croceum increased root growth especially, whereas Lactarius rufus increased needle growth and Suillus variegatus I, II and III improved both root and needle growth. All the EM fungi also significantly affected stem growth. Nitrogen concentration of the peat did not affect seedling growth as much as the EM fungi. At the lowest peat N concentration (1.17%) NH 4 + mineralisation was lower and DON (dissolved organic nitrogen) accumulation higher than at higher peat N concentrations. The EM fungal isolates had different effects on NH 4 + and DON accumulation/degradation in peat. The EM fungal isolates significantly increased NH 4 + formation in the peat, whereas L. rufus and P. croceum had an opposite effect on DON accumulation. S. variegatus I significantly decreased the DON concentrations during peat incubation. The N concentration of the peat slightly affected the utilization of amino acids and polyamines by the microbial community, whereas inoculation with S. variegatus I, II or III had no effect.

Radioactive Contamination of Ukrainian Mushrooms

Even 18 years after the Chernobyl catastrophe, radioactive contamination of wild growing mushrooms, in some cases reaching very high levels, created human health problems resulting from their nutritional and medicinal use. According to radioecological evaluations, the internal dose of irradiation in this case may reach 40−60%. A combination of macro- and micromycetes mycelial biomass and its capacity to uptake and retain radionuclides play very important roles in their migration and distribution. Actually, knowledge about the mechanisms involved in the accumulation and retention is incomplete. There is a positive correlation among the levels of soil contamination, degree of humidity, pH, rainfall, and radionuclide accumulation in mushrooms, although the species and ecological specificities of uptake are also observed. To measure species specificity of uptake, species-hyperaccumulators—for instance, radiocaesium—were used as bioindicators of contaminated soils. Among them, the widely spread and common species, Lactarius rufus (Scop.:Fr.) Fr. and Paxillus involutus (Batsch:Fr.) Fr., not consumed by the population because of their inedibility and toxicity, are now the most convenient test objects for long-term monitoring.During the last few years in about 80% of mushroom samples traditionally included in the Ukrainian diet—species of Boletaceae (Xerocomus spp., Suillus spp., Leccinum scabrum (Bull.:Fr.) S.F.Gray, Boletus edulis Bull.:Fr.) and Cantharellus cibarius (Fr.:Fr.) Fr. taken from areas with an average soil contamination of 0.1−5 Ci/km2 (presently, the collecting and consuming of wild growing mushrooms are practically not controlled)—the 137Cs levels exceeded permissible limits adopted in the Ukraine (2500 Bq/kg d.w.). Mushrooms growing in the Exclusion Zone, in the vicinity of the Chernobyl Power Plant (with 137Cs contamination density of 837 Ci/km2) accumulated up to millions of Bq/kg d.w. In 2004 137Cs activity in samples from the location of Novo-Shepelychi was within (in Bk/kg d.w.) 340,000 (Armillariella mellea (Vahl.:Fr.) P.Kumm.) to 20,000,000 (Xerocomus subtomentosus (L.:Fr.) Quél.), and 90Sr within 2000 (X. subtomentosus) to 13,000 (Stropharia aeruginosa (W.Curt.:Fr.) Quél.). Transfer factors for 137Cs were in X. subtomentosus 645, P. involutus 548, Lactarius turpis (Weinm.)Fr.280, L. deliciosus (L.:Fr.) S.F.Gray 222; for 90Sr Tf were in S. aeruginosa 6.0, L. turpis 5.1,A. mellea 3.1. The ratio of 137Cs/90Sr was within the range of 7.5−10,000. Mushrooms growing on the highly contaminated territories are permanently subjected to chronic irradiation. Taking into account polymorphism peculiar to mushrooms, the direct finding of morphose for them is difficult. Microstructural morphology of three bioindicative species using light and electron scanning microscopy was studied. It was statistically established that the spore length in Xerocomus badius (Fr.:Fr.) Kuhn. ex Gilb., Paxillus involutus, and Lactarius turpis samples collected in the Exclusion Zone was bigger than in the controls. In some cases, in the hymenophore of studied samples, parts with abnormally large as well as with very small spores were found. The observed variability indicated that high dosages resulting from radionuclides incorporated by mycelium and fruiting bodies from contaminated soils affect the hereditary structures of mushrooms.In nature mushrooms accumulate less 90Sr than 137Cs. In cultivation conditions, increasing levels of radiostrontium accumulation for Lentinus edodes (Berk.) Singer and Pleurotus ostreatus (Jacq.:Fr.)P. Kumm. (Grodzinskaya and Kuchma, 2004) were observed. This phenomenon can be connected to the higher biological availability of 90Sr from mixed and watered substrates. An increase of 90Sr activity in wood (observed in the last few years in contaminated territories) inevitably will cause an increase in its content in lignotroph species. Therefore, the selective control of 90Sr accumulation in cultivated lignotrophs, even in territories with low surface soil contamination, is strongly recommended.

Cadmium in upland forests after vitality fertilization with wood ash?a summary of soil microbiological studies into the potential risk of cadmium release

The use of wood ash in forestry has been questioned because of the potential risk associated with its cadmium (Cd) content (1–30 mg kg−1). In agriculture, wood ash is only allowed for use as a fertilizer when its Cd content is below 3 mg kg−1. This restriction has not been applied to forest soils and there is a lack of knowledge about the potentially harmful effects of the Cd in wood ash on forest ecosystems. This paper summarizes our recent studies on the microbial communities of boreal coniferous forest humus exposed to Cd-containing wood ash treatment. The main objectives of our studies were to test if the Cd in wood ash has the potential to affect the humus layer microflora of coniferous upland forests and if it has the potential to enter the human food chain. These objectives were tested both in laboratory and field experiments with ash and ash spiked with Cd (in laboratory 400 or 1,000 mg Cd kg−1 as CdO or CdCl2; in field 400 mg Cd kg−1 as CdO). In one study the dissolution of ash was accelerated by irrigating it with simulated acid rain (SAR). Wood ash increased humus layer pH and microbial activities (respiration or thymidine incorporation rates) and changed its microfloral community structure (Biolog, PLFA, 16S or 18S rDNA PCR-DGGE) in both laboratory and field experiments. Spiking ash with Cd induced no further changes in the above-mentioned variables compared to ash alone. The Cd added with wood ash did not become bioavailable as detected with a bacterial biosensor Bacillus subtilis BR151(pTOO24). The form and level of Cd added in the ash had no further effect on the microbiological variables studied. Irrigation of ash with SAR did not increase the amount of bioavailable Cd, although the dissolution rate of the ash was increased. The concentration of Cd in soil water and in the berries of Vaccinium uliginosum and V. vitis-idaea, and the amount of humus bioavailable Cd did not increase with applied ash or ash spiked with Cd although the ash spiked with Cd increased the amount of humus total and extractable Cd in the 4-year field study. Only the ash spiked with Cd and not the unspiked “normal” wood ash resulted in significantly higher Cd concentrations in the mushroom Lactarius rufus and a slight increase in the berries of Empetrum nigrum (first year only). In conclusion, the Cd in wood ash did not become bioavailable and harmful to forest soil microbes, or leach into the humus layer even when treated with simulated acid rain. It is thus safe to use wood ash as a fertilizer in forests. However, since wood ash adds Cd to the environment, it is recommended that the same sites should not be fertilized with wood ash more than once. The effects of wood ash (3 t ha−1) on forest soil humus layer microbes are long-term, lasting at least 20 years, and probably longer if higher application dose and/or hardened ash is used.

Cadmium-containing wood ash in a pine forest: effects on humus microflora and cadmium concentrations in mushrooms, berries, and needles

The cadmium (Cd) concentration of wood ash (1–30 mg·kg–1) is higher than allowed for agriculture fertilizers (3 mg·kg–1). Therefore, the objectives of this field study were to test if the Cd of wood ash has the potential to affect the coniferous forest humus microflora and if Cd enters the human food chain. These objectives were tested with ash (A) and Cd-spiked ash (ACd, 400 mg Cd·kg–1) at a fertilization rate of 3 t·ha–1. Microbial community structure, respiration, needle litter decomposition, growth rates and Cd tolerance of bacteria, and the bioavailability of Cd were measured. Also, Cd concentrations of humus, soil percolation water, mushrooms, fruits and leaves of berries, and needles were determined. The amount of Cd in the percolation water or bioavailable Cd, measured with a bacterial biosensor, and Cd tolerance of bacteria did not increase, although the ACd treatment increased the amount of humus total and extractable Cd. Only the ACd and not the A treatment caused Cd concentration increment in Lactarius rufus and berries of Empetrum nigrum. In spite of the high Cd concentration of the spiked ash, it did not have harmful effects on humus microorganisms during this 4-year study. Thus, wood ash is safe to use as a fertilizer in forests.

A comparison of mycorrhizal and saprotrophic fungus tolerance to creosote in vitro

Twenty-six isolates (18 species) of mycorrhizal fungi and 13 isolates (13 species) of saprotrophic decay fungi were grown on agar amended with 25, 50 and 100 ppm creosote. All saprotrophic fungi exhibited some tolerance to creosote; 11 of 13 saprotrophic fungal isolates (85%) had intermediate, high or complete tolerance to creosote. However, only 12 of 26 mycorrhizal fungal isolates (46%) had comparable tolerance to creosote. Of the saprotrophic fungi, Irpex lacteus , Neolentinus lepideus , Ouedemansiella radicata , Phanaerochaete chrysosporium , Postia placenta and Trametes versicolor exhibited the greatest tolerance to creosote. Of the mycorrhizal fungi, Cenococcum geophilum , Laccaria bicolor (one isolate), Laccaria laccata (one isolate) and Suillus granulatus exhibited the highest tolerance to creosote. Mycorrhizal fungi with either very low or no tolerance (killed) by creosote were Amanita flavoconia , Astraeus hygrometricus , Lactarius rufus , Pisolithus tinctorius , and Scleroderma citrinum .

Radiocesium Contamination of Wild-Growing Medicinal Mushrooms in Ukraine

Concentrations of 134Cs and 137Cs in fruiting bodies of 98 species of wild-growing mushrooms and substrates from their habitats (652 samples in all), collected in 1993, 1996, 1998, and 1999 in 73 locations of Kiev, Chernigiv, Zhytomyr, and Volyn' regions of Ukraine, were studied by gamma-spectrometric methods. Radiocesium content in mushrooms varied over a wide range. A maximum level of 137Cs at 17,117,000 Bq/kg d.w. was found in samples from the Chernobyl area in 1993 in fruiting bodies of Gomphidius glutinosus, and at 13,203,906 Bq/kg d.w. in Lactarius turpis. In 1998 the level in Boletus edulis was 10,833,333 Bq/kg d.w. and in Suillus luteus it was up to 13,869,532 Bq/kg d.w. In 1999 in S. luteus it was 12,918,330 Bq/kg d.w. Interspecific differences in levels of radiocesium accumulation among the studied mushroom species from the same habitat reached 103 times. A comparison of obtained data with previous data showed that the highest levels of radiocesium were in mycosymbiotrophs: some representatives of the families Russulaceae (Lactarius helvus, L. turpis, L. rufus), Boletaceae (Xerocomus badius, Suillus luteus, Leccinum scabrum, Boletus edulis), Gomphidiaceae (G. glutinosus), Paxillaceae (Paxillus involutus, P. atrotomentosus), Cortinariaceae (Hebeloma crustuliniforme, Cortinarius praestans), Amanitaceae (Amanita phalloides, A. muscaria, A. citrina). Hence they could be considered hyperaccumulators of radioactive fission decay products and they could be used for long-term radioecological monitoring of the areas contaminated as a result of the Chernobyl accident. The coefficients of accumulation in 1996 remained high: in Paxillus trotomentosus at 1,180, in Lactarius helvus up to 855, in Hebeloma crustuliniforme at 514, in Xerocomus badius up to 256, in Boletus edulis up to 174; in 1998 in Xerocomus badius at 153, in Lactarius rufus at 111, in Amanita phalloides at 71; in 1999 in Paxillus involutus up to 928, in Suillus luteus at 766, in Sarcodon imbricatus at 238, in Cortinarius praestans at 187, in Amanita muscaria at 174, and in Xerocomus badius at 94.

The decomposition of wood mass under conditions of climax spruce stands and related mycoflora in the Krkonoše Mountains

The mycoflora was investigated under the conditions of climax spruce stands in the Krkonoše Mountains in relation to wood decomposition. The areas under observation have been affected more or less by air pollution since the eighties. The average mass of deadwood found on the plots is 124 m<sup>3</sup> per ha – the mass of fallen trunks is about 32 m3 per ha, mean value from total average. About 128 species of macrofungi were identified that besides others included 43 species of wood-decaying fungi. Also 54 mycorrhizal species were identified. Among the mycorrhizal fungi about 10 species were dominant, such as Laccaria laccata (Scop.: Fr.) Cooke, Lactarius helvus Fr., Lactarius mitissimus Fr., Lactarius rufus (Scop.) Fr., Russula emetica (Schaeff.: Fr.) Pers. and Russula ochroleuca Pers. etc. Concerning the volume of decomposed wood on monitored plots in climax spruce stands, the prevalent wood-decaying fungi are brown rot fungi. The proportion of brown rot fungi in wood decomposition is 60–95% of deadwood mass on the plots of climax spruce stands. A dominant species is Fomitopsis pinicola (Sw.: Fr.) P. Karst. causing the brown rot. Concerning the group of white rot fungi, the most important is Stereum sanguinolentum (Alb. & Schw.: Fr.) Fr., participating by 17% in wood decomposition on plots damaged by deer.

Identification of genes for lignin peroxidases and manganese peroxidases in ectomycorrhizal fungi.

• Genes for ligninolytic enzymes, normally associated with white-rot fungi, are shown to be widespread in a broad taxonomic range of ectomycorrhizal (ECM) fungi. • ECM fungi were screened for lignin peroxidase (LiP) and manganese peroxidase (MnP) genes by PCR using primers specific for known isozymes in the white-rot fungus Phanerochaete chrysosporium, with DNA sequencing used to confirm the identity of the amplified fragments. • Genes for LiPs were detected in ECM fungi representing the orders Agaricales, Aphyllophorales, Boletales, Cantharellales, Hymenochaetales, Sclerodermatales, Stereales and Thelephorales. MnP genes were detected in only Cortinarius rotundisporus and three ECM Stereales taxa. • The presence of genes for decomposer activities supports putative evolutionary relationships between ECM and saprotrophic fungi. Expression of the lignolytic genes may facilitate ECM fungal access to nutrients associated with dead plant material in soil and potentially a supplementary carbon supply. Strict functional boundaries between ECM and decomposer fungi may be less clear-cut than previously thought.

Effect of organic and inorganic nitrogen sources on endogenous polyamines and growth of ectomycorrhizal fungi in pure culture

The abilities of three ectomycorrhizal fungi, Paxillus involutus, Suillusvariegatus and Lactarius rufus, to utilize organic and inorganic nitrogen sources were determined by measuring the growth and endogenous free polyamines (putrescine, spermidine and spermine) of pure culture mycelium. Differences were found in the utilization of the nitrogen sources and in the polyamine concentrations between the fungal species and between isolates of L. rufus. All the fungi grew well on ammonium and on several amino acids. Endogenous polyamine levels varied with the nitrogen source. Spermidine was commonly the most abundant polyamine; however, more putrescine than spermidine was found in P. involutus growing on inorganic nitrogen or arginine. Low amounts of spermine were found in S. variegatus and some samples of L. rufus. None or only a trace of spermine was found in P. involutus mycelium. In all fungi, putrescine concentrations were higher with ammonium than with the nitrate treatment. The total nitrogen content of peat did not determine the ability of L. rufus strains isolated from peatland forest sites to utilize organic nitrogen.

The concentrations and bioconcentration factors of mercury in mushrooms from the Mierzeja Wiślana sand-bar, Northern Poland

The total concentration of mercury was determined in 15 species of wild growing mushrooms, each represented by 15 specimens including underlying substrate, collected from the unpolluted area of the sand-bar Mierzeja Wiślana in the northern part of Poland in 1993–1994. Mercury was measured by cold vapour atomic absorption spectrometry (CV-AAS) after wet digestion of the samples with concentrated nitric acid in a glass system. The mushroom species examined showed a wide range of mercury concentrations, i.e. from 5.6 ± 2.1 μg/g dry wt. in Scleroderma citrinum to 1100 ± 240 μg/g in the edible Macrolepiota procera. No bioconcentration of mercury was observed in Xerocomus badius, Paxilus involutus, Russula queletii and Lactarius rufus. In Hygrophorius aurantiaca, Armilariella mellea and Amanita vaginata the bioconcentration factor (BCF) values of mercury were close to one. Accumulation of mercury was slight in Oudemansiella platyphylla and Amanita citrica (BCF between 2.0 and 3.3 in the caps and 1.7 in the stalks) and high in Leccinum scabrum, Amanita muscaria and Macrolepiota procera (BCFs between 11 and 35 in the caps and 6.7–18 in the stalks). In the whole fruiting body of Polyporus melanopsuss and Scleroderma citrinum the BCF values of mercury were 4.4 and 0.083, respectively. There was a high correlation between the concentrations of mercury in the caps and stalks of Macrolepiota procera and in the underlying substrate ( P < 0.001), a slight correlation for Polyporus melanopsuss, and also for the caps of Leccinum scabrum, Oudemansiella platyphylla and Russula aeruginea and the stalks of Hygrophoropsis aurantiaca ( P < 0.01) and L. scabrum ( P < 0.05). For the other mushroom species investigated there was no correlation between mercury concentration in the fruiting bodies and underlying substrate.

Mycorrhizal colonization and lead distribution in root tissues of Norway spruce seedlings

AbstractNon‐inoculated spruce seedlings (Picea abies Karst.) and spruce seedlings colonized with Lactarius rufus Fr., Pisolithus tinctorius Coker &amp; Couch or Paxillus involutus Fr. were grown for 35 or 37 weeks in a microcosm system on two types of natural forest humus differing in Pb content. Using X‐ray microanalysis, the distribution and content of Pb in the tissues of mycorrhizal and non‐mycorrhizal root tips were compared. No significant difference in the Pb contents of root cortex cell walls of non‐mycorrhizal and seedlings colonized by Lactarius rufus, Pisolithus tinctorius, or indigenous mycorrhizal fungi (mainly Tylospora sp.) was found. However, in root tips of seedlings colonized by Paxillus involutus, due to a higher binding capacity for cations, the Pb content in cell walls of the root cortex were higher than in non‐mycorrhizal roots. Pb contents in cell walls of the cortex of mycorrhizal and non‐mycorrhizal roots were 3 times higher in plants growing in humus with a high Pb content than in plants growing in humus with a low Pb content. It is concluded that increasing contents of Pb in the organic matter may lead to an increased loading of the apoplast with Pb. The mycobionts tested in this investigation did not exclude Pb from root tissues.

Radiocaesium in fruitbodies and mycorrhizae in ectomycorrhizal fungi

Fruitbodies of Suillus variegatus and Lactarius rufus and, at a maximum distance of 50 cm, the corresponding mycorrhizae, were collected on a rocky area in a coniferous forest. The tuberculate mycorrhizae collected close to S. variegatus fruitbodies were identified by the RFLP pattern to be S. variegatus mycorrhizae. In contrast the smooth brown mycorrhizae collected close to fruitbodies of L. rufus were found to be of various species — L. rufus, but also Russula sp. The 137Cs activity concentrations in fruitbodies and the fungal part of the tuberculate mycorrhizae of S. variegatus were about the same. A local enrichment of 137Cs within fruit-bodies was studied by collecting fruitbodies growing in clusters. Between 13 and 64% of the mean ground 137Cs deposition of the cluster area (400 or 625 cm 2) was found in the fruitbodies. This indicates that there might be an important fungal redistribution of 137Cs in the forest floor during the production of fruitbodies. The distribution of 137Cs within the fruitbodies was heterogenous. For example in Cortinarious armillatus, the 137Cs level in the cap was 2.7 times higher compared to in the stripe.

Utilization of sucrose by Hymenoscyphus ericae (an ericoid endomycorrhizal fungus) and ectomycorrhizal fungi

Hymenoscyphus ericae utilized sucrose, whereas the ectomycorrhizal fungi either showed poor growth or responded to the presence of sucrose after a lag phase. On sucrose-containing media, fructose and glucose accumulated in the medium at the end of the linear phase of growth of H. ericae and then disappeared during the stationary phase. Dry mass of H. ericae increased with increasing concentration of both sucrose and glucose up to 2·0 g C l −1 , whereas on fructose, it increased up to 4 g C l −1 . Growth of H. ericae was doubled on media containing both glucose and fructose at 1:1 ratio compared with growth on either hexose alone at the same carbon concentration. Sucrose, fructose and glucose were detected in the mycelium of H. ericae , although the main soluble carbohydrates were mannitol and trehalose. Growth of ectomycorrhizal fungi (excluding Cenococcum geophilum ) on sucrose depended solely on the presence of hexoses in the medium and utilization of sucrose was poor. The use of ‘starter glucose’ had an effect on sucrose utilization by Laccaria laccata, Lactarius rufus, Paxillus involutus and Thelephora terrestris but growth was still less than that on equivalent amounts of glucose. These results confirm previous studies that the majority of ectomycorrhizal associations do not utilize sucrose directly and may have to rely on apoplastic host invertase. In contrast, host invertases may not be required in the utilization of sucrose by ericoid mycorrhizal associations.