Individual Fruiting Bodies Research Articles

English

The aim of this study was to investigate the effect of substrates on the growth, yield, nutritional, and medicinal value of Pleurotus ostreatus supplemented with four medicinal plants. A completely randomized block design was laid out with 4 treatments replicated 4 times with and without medicinal plants. T1 (sawdust), T2 (sawdust + corncobs), T3 (palm cones), and T4 (elephant stalks) were the treatments used. Croton macrastarchus, Harungana madagascariensis, Tithonia diversifolia, and Rauwolfia vomitoria were the medicinal plants used. Nutritional and phytochemical analysis was carried out. Sawdust + corn cobs indicated the highest effect on growth as it had the highest mean height (19.5 ± 3.3 cm), diameter (29.0 ± 4.3 cm) and mean weight of individual fruiting bodies (175.8 ± 84.3 cm). Biological efficiency was highest in palm cones (77.1%), second by sawdust + corn cobs (61.1%), saw dust (53.0%) and elephant stalk (6.3%). The protein content was highest in sawdust + corn cobs (12.4 g), lipid concentration highest in sawdust only (1.51 g), total carbohydrate highest in palm cones (82.98 g), and total ash highest in sawdust only (7.32 g) per 100 g. The supplementation of sawdust + corn cobs with R. vomitoria had the highest phytochemical components.   Key words: Medicinal properties, mushroom cultivation, growth and yield, nutritional content, Pleurotus ostreatus, medicinal plants substrates.

Geographical-based variations in white truffle Tuber magnatum aroma is explained by quantitative differences in key volatile compounds.

The factors that vary the aroma of Tuber magnatum fruiting bodies are poorly understood. The study determined the headspace aroma composition, sensory aroma profiles, maturity and bacterial communities from T.magnatum originating from Italy, Croatia, Hungary, and Serbia, and tested if truffle aroma is dependent on provenance and if fruiting body volatiles are explained by maturity and/or bacterial communities. Headspace volatile profiles were determined using gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and aroma of fruiting body extracts were sensorially assessed. Fruiting body maturity was estimated through spore melanisation. Bacterial community was determined using 16S rRNA amplicon sequencing. Main odour active compounds were present in all truffles but varied in concentration. Aroma of truffle extracts were sensorially discriminated by sites. However, volatile profiles of individual fruiting bodies varied more within sites than across geographic area, while maturity level did not play a role. Bacterial communities varied highly and were partially explained by provenance. A few rare bacterial operational taxonomical units associated with a select few nonodour active volatile compounds. Specificities of the aroma of T.magnatum truffles are more likely to be linked to individual properties than provenance. Some constituents of bacteria may provide biomarkers of provenance and be linked to nonodour active volatiles.

Вплив складу субстратів на морфологічні та біохімічні показники Pleurotus citrinopileatus Singer

Goal. To find out the influence of substrate compositions made of agricultural residues (barley straw and sunflower husk) on the morphological characteristics of sprouts and individual fruiting bodies of P. citrinopileatus, as well as on the biochemical parameters of fungal raw materials. Methods. Empirical analysis and synthesis, computational and analytical, statistical. Results. Due to the mixing of plant materials in the calculated proportion, the desired ratio of organogenic elements (C/N) was achieved, but the different structures of the components caused a significant difference between the humidity and density of the obtained substrates. It was determined that the composition of the manufactured substrates did not have a statistically proven effect on the main technical characteristics of the growths: weight, size and the total number of fruiting bodies in the sprouts (p>0.05), while the morphological characteristics of individual fruiting bodies differed significantly. Statistically proven dependence of the biochemical composition of fruiting bodies on changes in the components of plant residues in the formula of the substrate was not detected, but the U-test with the use of comparison of the average values had proved an increase in protein in the dry matter to 32.07±0.27% at the use of substrate № 3, which was 8% higher than in fruiting bodies obtained from the substrate № 1. Conclusions. The possibility of using available local agricultural residues (barley straw and sunflower husk) for the cultivation of the fungus P. citrinopileatus, a valuable edible species with proven healing properties, has been determined. The technological characteristics of the sprouts were analyzed, which made it possible to calculate the size of the container to reduce mechanical damage to the mushrooms during packaging. The influence of the substrate composition on the morphological features and biochemical composition of fruiting bodies was statistically proved. A positive correlation was found between the content of ash substances in the substrate and the obtained fruiting bodies.

Analysis of the biological efficiency and quality factors of mushrooms of the genus Pleurotus (Fr.) P.Kumm as a model of effective cultivation of lignicolous fungi with high functional value

Purpose. Morphological and organoleptic evaluation of oyster mushroom strains for selection of highly productive cultivars assortment with valuable consumer properties for winter and summer cultivation and suitability for sale in fresh or processed form were investigated.Methods. The scheme of the experiment included six strains of oyster mushrooms belonging to two species: Pleurotus ostreatus (5 strains: 2301, Z, 2316, 2456, 431) and P. pulmonarius (2314). Laboratory, laboratory-industrial and statistical methods are used.Results. The dynamics of agrochemical parameters of substrates obtained by the method of aerobic fermentation in the high layer proved their optimality according to the main criteria and compliance to regulatory documentation. The biological efficiency of the strains was in the range of 40–78.9%. The highest weight of clusters was found in the “summer” strain 431 (430.7 g). The highest weight of the fruiting body was determined for the strain 2301 (15.2 g), the lowest – for the 2456 (3.3 g).Conclusions. The values of biological efficiency of strains was determined. The highest average values for the first flush of fruiting had strains 2316 (78.9%) from the “winter” group (A) and 431 (78.4%) from the “summer” group (B). According to the results of statistical analysis, significant differences were revealed between the studied strains in the main morphological indicators of clusters. It was found that the mass of clusters of «winter» cultivars is much less dependent on the strain type (220.8–273.4 g) than that of «summer» cultivars (83.4–430.7 g). The index of the asymmetry coefficient of the cluster, which can be useful for calculating the required container sizes was proposed. It was determined that the morphological features of fruiting bodies had significant differences in all studied parameters. In particular, the A group strains differed in size and weight. It was proposed the index of weight loss of the crop coefficient, which shows the ratio between the cap and stipe of the fruiting body and make it possible to predict the amount of mushroom raw material that will be sold in the form of caps, and the amount of raw material that can be processed into minced mushroom, powder and others. The best coefficient was obtained for the fruiting bodies of strain 2314 (0.87), and the worst – for 2456 (0.59), which, accordingly, is not recommended for sale by individual fruiting bodies. It was found that the fruiting bodies of high-yielding strains 2316 and 431 had a number of organoleptic defects.

Stability of psilocybin and its four analogs in the biomass of the psychotropic mushroom Psilocybe cubensis.

Psilocybin, psilocin, baeocystin, norbaeocystin, and aeruginascin are tryptamines structurally similar to the neurotransmitter serotonin. Psilocybin and its pharmacologically active metabolite psilocin in particular are known for their psychoactive effects. These substances typically occur in most species of the genus Psilocybe (Fungi, Strophariaceae). Even the sclerotia of some of these fungi known as "magic truffles" are of growing interest in microdosing due to them improving cognitive function studies. In addition to microdosing studies, psilocybin has also been applied in clinical studies, but only its pure form has been administrated so far. Moreover, the determination of tryptamine alkaloids is used in forensic analysis. In this study, freshly cultivated fruit bodies of Psilocybe cubensis were used for monitoring stability (including storage and processing conditions of fruiting bodies). Furthermore, mycelium and the individual parts of the fruiting bodies (caps, stipes, and basidiospores) were also examined. The concentration of tryptamines in final extracts was analyzed using ultra-high-performance liquid chromatography coupled with mass spectrometry. No tryptamines were detected in the basidiospores, and only psilocin was present at 0.47 wt.% in the mycelium. The stipes contained approximately half the amount of tryptamine alkaloids (0.52 wt.%) than the caps (1.03 wt.%); however, these results were not statistically significant, as the concentration of tryptamines in individual fruiting bodies is highly variable. The storage conditions showed that the highest degradation of tryptamines was seen in fresh mushrooms stored at -80°C, and the lowest decay was seen in dried biomass stored in the dark at room temperature.

Distribution of major and trace elements in the bolete mushroom Suillus luteus and the bioavailability of rare earth elements

Fungi are eukaryotic organisms within the kingdom Fungi. They are classified as macrofungi when they produce, usually above-ground, fruit bodies which are often simply referred to as “mushrooms”. Since many species are edible, numerous studies discuss major elements and the accumulation of toxic and radioactive elements. Rare earth elements are economically important metals which are increasingly used for high-technology applications like renewable energies and state-of-the-art electronic devices. Although the significantly increasing anthropogenic input into the environment may affect living organisms, available data on the concentration, distribution and uptake of rare earth elements and yttrium (REY) by fungi are limited and often ambiguous.Here, we present trace element and REY concentrations for the fungus species Suillus luteus and the distribution of major and trace elements between the different compartments of individual fruit bodies separated into cuticle, flesh of cap, tubes & pores, and stipe. Our results show that P, K, Zn, Rb and Cs are the only elements enriched in fruit bodies relative to soil. All elements are unevenly distributed within the fruit bodies and the parts comprising the cap generally contain higher concentrations of trace elements than the stipes. The total REY concentrations in the individual mushroom parts range from 13.1 μg kg−1 in dry matter (DM) to 72.6 μg kg−1 DM, whereas concentrations in the whole mushrooms are 13.4 to 74.2 μg kg−1 DM. The highest of the generally rather low REY concentrations are shown by the cuticles. All mushroom parts have the same rather flat shale-normalized REY patterns very similar to those of ambient soil, but show positive Y anomalies in all and positive La anomalies in most samples. The cuticles and the whole fruit bodies show a slight depletion of light relative to heavy REY (LREY and HREY, resp.), while flesh, tubes & pores and the stipe exhibit no or a small enrichment of LREY relative to HREY. The fractionation between LREY and MREY is only small, whereas the fractionation between MREY and HREY is more pronounced. Soil leaching experiments with the siderophore desferrioxamine B suggest that although Suillus luteus produces siderophores which are important ligands for REY complexation, such hydroxamate siderophores do not significantly affect REY mobilization and transport to the mushrooms. The close similarity of the REY distribution in the fruit bodies of Suillus luteus and ambient soil and the lack of significant fractionation suggest that fungi may have the potential to be developed into bioarchives for tracers used in geochemical exploration.

The biogeography of kin discrimination across microbial neighbourhoods.

The spatial distribution of potential interactants is critical to social evolution in all cooperative organisms. Yet the biogeography of microbial kin discrimination at the scales most relevant to social interactions is poorly understood. Here we resolve the microbiogeography of social identity and genetic relatedness in local populations of the model cooperative bacterium Myxococcus xanthus at small spatial scales, across which the potential for dispersal is high. Using two criteria of relatedness—colony‐merger compatibility during cooperative motility and DNA‐sequence similarity at highly polymorphic loci—we find that relatedness decreases greatly with spatial distance even across the smallest scale transition. Both social relatedness and genetic relatedness are maximal within individual fruiting bodies at the micrometre scale but are much lower already across adjacent fruiting bodies at the millimetre scale. Genetic relatedness was found to be yet lower among centimetre‐scale samples, whereas social allotype relatedness decreased further only at the metre scale, at and beyond which the probability of social or genetic identity among randomly sampled isolates is effectively zero. Thus, in M. xanthus, high‐relatedness patches form a rich mosaic of diverse social allotypes across fruiting body neighbourhoods at the millimetre scale and beyond. Individuals that migrate even short distances across adjacent groups will frequently encounter allotypic conspecifics and territorial kin discrimination may profoundly influence the spatial dynamics of local migration. Finally, we also found that the phylogenetic scope of intraspecific biogeographic analysis can affect the detection of spatial structure, as some patterns evident in clade‐specific analysis were masked by simultaneous analysis of all strains.

Rhizopogon roseolus basidiospore germination decreases as the fruiting bodies mature and the spore wall becomes more complex

Rhizopogon roseolus (Corda) Th. Fr. is a basidiomycete truffle that is considered edible. Its gleba changes color from white to beige to brown as it matures. Although ultrastructural changes in the spore wall have been linked to the maturation of the fruiting body, little is known regarding the relationship between spore germination success and the ultrastructure of the spore wall. We examined spore germination on agar plates and analyzed the spore wall ultrastructure using transmission electron microscopy (TEM). Fruiting bodies, collected from a pine forest, were classified into three developmental stages based on gleba color, and the germination success was evaluated at each stage. Variability in the spore germination rate was observed between individual fruiting bodies. The peak germination rate was recorded for the spores from the fruiting bodies in the beige glebal stage, and the rate was lower in the brown glebal stage. When spore wall structures were studied using TEM, the spore wall was found to be multilayered upon maturation of the fruiting body. The spores of the beige glebal stage showed three types of spore walls, namely two-layered, three-layered, and four-layered spore walls. On the other hand, the spores of the brown glebal stage showed predominantly four-layered spore walls. These results indicate that spore germination of R. roseolus decreases as the fruiting body matures and the spore wall becomes more complex.

Development and growth of fruit bodies and crops of the button mushroom, Agaricus bisporus

We studied the appearance of fruit body primordia, the growth of individual fruit bodies and the development of the consecutive flushes of the crop. Relative growth, measured as cap expansion, was not constant. It started extremely rapidly, and slowed down to an exponential rate with diameter doubling of 1.7 d until fruit bodies showed maturation by veil breaking. Initially many outgrowing primordia were arrested, indicating nutritional competition. After reaching 10 mm diameter, no growth arrest occurred; all growing individuals, whether relatively large or small, showed an exponential increase of both cap diameter and biomass, until veil breaking. Biomass doubled in 0.8 d. Exponential growth indicates the absence of competition. Apparently there exist differential nutritional requirements for early growth and for later, continuing growth. Flushing was studied applying different picking sizes. An ordinary flushing pattern occurred at an immature picking size of 8 mm diameter (picking mushrooms once a day with a diameter above 8 mm). The smallest picking size yielded the highest number of mushrooms picked, confirming the competition and arrested growth of outgrowing primordia: competition seems less if outgrowing primordia are removed early. The flush duration (i.e. between the first and last picking moments) was not affected by picking size. At small picking size, the subsequent flushes were not fully separated in time but overlapped. Within 2 d after picking the first individuals of the first flush, primordia for the second flush started outgrowth. Our work supports the view that the acquisition of nutrients by the mycelium is demand rather than supply driven. For formation and early outgrowth of primordia, indications were found for an alternation of local and global control, at least in the casing layer. All these data combined, we postulate that flushing is the consequence of the depletion of some unknown specific nutrition required by outgrowing primordia.

Development of molecular markers and preliminary investigation of the population structure and mating system in one lineage of black morel (Morchella elata) in the Pacific Northwestern USA

Phylogenetic analysis of LSU/ITS sequence data revealed two distinct lineages among 44 morphologically similar fruiting bodies of natural black morels (Morchella elata group) sampled at three non-burn locations in the St Joe and Kanisku National Forests in northern Idaho. Most of the sampled isolates (n = 34) represented a dominant LSU/ITS haplotype present at all three sites and identical to the Mel-12 phylogenetic lineage (GU551425) identified in a previous study. Variation at 1–3 nucleotide sites was detected among a small number of isolates (n = 6) within this well supported clade (94%). Four isolates sampled from a single location were in a well supported clade (97%) distinct from the dominant haplotypes and may represent a previously un-sampled, cryptic phylogenetic species. Species-specific SNP and SCAR markers were developed for Mel-12 lineage isolates by cloning and sequencing AFLP amplicons, and segregation of AFLP markers were studied from single ascospore isolates from individual fruiting bodies. Based on the segregation of AFLP markers within single fruiting bodies, split decomposition analyses of two SCAR markers, and population genetic analyses of SNP, SCAR, and AFLP markers, it appears that members of the Morchella sp. Mel-12 phylogenetic lineage are heterothallic and outcross in nature similar to yellow morels. This is the first set of locus-specific molecular markers that has been developed for any Morchella species, to our knowledge. These markers will prove to be valuable tools to study mating system, gene flow and genetic structure of black morels at various spatial scales with field-collected fruiting bodies and eliminate the need to culture samples in vitro.

Extraction and characterization of pigment from Sclerotinia sp. and its use in dyeing cotton

The fruiting body of a cup fungus was collected from a compost pit containing fresh cow dung amended with biodynamic herbal preparations. The fungus was identified as Sclerotinia sp. by following standard procedures. The mycelial growth of S clerotinia sp. on cow pat pit manure was monitored for 90 days and on day 5 pin head primordia were observed and matured into individual fruiting bodies (0.5 cm diameter each, 1 gram fresh weight) on day 20. The fruiting body started yielding dark green spores and the spore deposits were seen on the top surface of the fruiting body. The spores are liberated from the fruiting bodies when they receive an external stimulus. The Sclerotinia sp. spore was elliptical in shape and was 2 µm in size when examined under phase contrast microscope at 40x. The dark green spore of Sclerotinia sp. excretes a pinkish red pigment in distilled water (pH 6.5). Spectrophotometer scanning (200—800 nm) of the pigment showed three peaks: 507 nm (optical density (O.D.) 0.554), 525 nm (O.D. 0.629), and 545 nm (O.D. 0.567). The pigment had high protein content (0.332 mg/ml) but no deductible amount of carbohydrates or lipids. Stability of the pigment was tested at various temperatures (40—100°C) and no change in its original color was observed under UV—visible spectral scan analysis. Pigment from Sclerotinia sp. changed its original pinkish red color at various pH values (pH 2.0, 3.0, and 14.0). The antibacterial activity of this pigment extract was tested on seven different bacteria of which a zone of inhibition was observed for E. coli. The pigment from Sclerotinia sp. applied on cotton yarns pretreated with different mordants gave different color shades, which were confirmed using the standard color code index.

Cadmium accumulation in Agaricusblazei Murrill

AbstractBACKGROUND: Agaricus blazei Murrill has become a popular food source of high nutritional and medicinal value in many Asian countries. However, there are growing health concerns on cadmium (Cd) accumulation by A. blazei. Experiments were conducted to investigate Cd accumulation patterns in A. blazei and to identify key factors contributing to Cd accumulation.RESULTS: Cd concentrations in the substrates and subsequent fruit bodies declined rapidly after the first, second and third harvest wave. A quick rinse of the fruit bodies in water reduced the Cd concentration by 27–54% depending on the strain. The Cd concentration in the fruit bodies decreased as the fruit body yield m−2 or fruit body number m−2 increased, while it increased as the substrate Cd content or fruit body size increased. Cd accumulation was positively associated with phosphorus (P) uptake.CONCLUSION: The results suggests that, in the A. blazei‐growing region studied, Cd and P concentrations in the substrates and casing soil should be reduced in order to effectively minimise Cd accumulation in the fruit bodies. It is also necessary to improve fruit body yield by increasing the number of medium‐sized fruit bodies. Overgrowth of individual fruit bodies stimulates Cd accumulation in A. blazei. Copyright © 2008 Society of Chemical Industry

Abundance and viability of fungal spores along a forestry gradient – responses to habitat loss and isolation?

Regional variation in spore deposition and viability was studied for two fungi, Fomitopsis rosea (Alb. & Schwein.: Fr.) P. Karst. and Phlebia centrifuga P. Karst., both confined to old‐growth spruce forests in the boreal zone. Seven regions in Sweden were studied along a north‐south transect in which the historical impact from forestry increases and the amount old forests decreases towards the south. The two southernmost regions were located outside the distribution border of the species. Spore deposition was measured species specifically as heterokaryotisation of homokaryotic mycelia growing on wood discs. There was a significant decline in spore deposition towards the south for both species. F. rosea deposited an average amount of 111 spores m−2 24 h−1 in the northernmost region compared to less than 1 spore in the four southernmost regions. The corresponding values for P. centrifuga were 27 spores m−2 24 h−1 in the north compared to less than 2 spores in the 4 southernmost regions. No deposition was found south of the distribution borders. The viability of spores from local populations within each region was measured as germination success on nutrient media. Individual fruiting bodies from large populations in the north generally produced spores with higher germinability than fruiting bodies from geographically isolated populations in the central and southern regions. However, there was a high variation among the southern populations. Our data suggest that some populations in mid‐ and south Sweden may suffer from negative genetic effects, possibly associated with fragmentation and loss of habitat. Thus, the combination of low spore deposition and low germinability of spores may be a threat to the long‐term persistence of F. rosea and P. centrifuga in southern Sweden. Several other species may experience the same situation, especially when considering the severe decline of dead wood in Swedish forests.

Phylogeny and genetic diversity of Bridgeoporus nobilissimus inferred using mitochondrial and nuclear rDNA sequences

The genetic diversity and phylogeny of Bridgeoporus nobilissimus have been analyzed. DNA was extracted from spores collected from individual fruiting bodies representing six geographically distinct populations in Oregon and Washington. Spore samples collected contained low levels of bacteria, yeast and a filamentous fungal species. Using taxon-specific PCR primers, it was possible to discriminate among rDNA from bacteria, yeast, a filamentous associate and B. nobilissimus. Nuclear rDNA internal transcribed spacer (ITS) region sequences of B. nobilissimus were compared among individuals representing six populations and were found to have less than 2% variation. These sequences also were used to design dual and nested PCR primers for B. nobilissimus-specific amplification. Mitochondrial small-subunit rDNA sequences were used in a phylogenetic analysis that placed B. nobilissimus in the hymenochaetoid clade, where it was associated with Oxyporus and Schizopora.

Sterol and vitamin D2 contents in some wild and cultivated mushrooms

Abstract The contents of vitamin D 2 and sterols in some wild and cultivated mushrooms were determined, and the distribution of these compounds in different parts of the wild mushrooms was evaluated. In addition, the variation in vitamin D 2 contents between individual fruiting bodies of wild mushrooms was studied. Vitamin D 2 was determined using an HPLC method, including saponification and semipreparative normal-phase HPLC purification before analytical reversed-phase quantification with an internal standard. Sterol contents were analysed with gas chromatography using an internal standard method, including saponification before derivatizing sterols to trimethylsilyl ethers. Mass-spectral analyses were used to further confirm the identification of sterols. Vitamin D 2 was almost totally absent in cultivated mushrooms, while some wild mushrooms contained high concentrations of this vitamin (4.7–194 μg/100 g dry weight). Ergosterol was the most abundant sterol found in mushrooms, and its contents were higher in cultivated mushrooms (602.1–678.6) than in wild mushrooms (296–489 mg/100 g dry weight). The contents of vitamin D 2 and ergosterol varied greatly and moderately, respectively, between different parts of the mushrooms and were lowest in stipes. In addition, high variation in vitamin D 2 contents between individual fruiting bodies was found.

The ergocalciferol content of dried pigmented and albino Cantharellus cibarius fruit bodies

The ergocalciferol (vitamin D2) content of individual fruit bodies of the edible mushroom Cantharellus cibarius (chanterelle) was measured with HPLC 2–6 years after drying. The concentrations of ergocalciferol in different fruit bodies varied between 0.12 and 6.30 μg g DW −1 , with a mean of 1.43 μg g DW −1 . This result indicates that dried and stored chanterelles contain significant amounts of ergocalciferol. The huge range in concentration challenges the validity of food tables based on means from pooled samples. The range may reflect differences in exposure to sun light, as fruit bodies within the same cluster showed little variation. Our study indicates that mycelial cultivation for ergocalciferol production is an interesting prospect if strains and incubation conditions are selected carefully. No significant difference in ergocalciferol concentration between pigmented and albino forms was found.

The translocation of caesium and silver by fungi in some Scottish soils

The caesium and silver content of the fruitbodies of fungi growing on some Scottish grassland sites have been measured. The distribution of caesium and silver in the soils has been measured and correlated with ergosterol as a measure of fungal biomass. Soil beneath individual fruitbodies and fairy rings was sampled from a clay loam, grassland site (Hogarth Park) in southwest Scotland, a sandy loam (Troon, southwest Scotland) and a peaty soil (Glensaugh, northeast Scotland). There is little or no information about the translocation of metals in soil by fairy ring fungi. Considerable variation in the ability of the fungi to translocate and accumulate the metals was observed. Cortinarius and Mycena Sp. and Suillus grevillei accumulated caesium and silver, whereas additionally Coprinus comatus, Entoloma Sp., Hygrocybe psittacina and Psathyrella Sp. accumulated silver. Clitocybe and Inocybe Sp., Lycoperdaceae and Marasmius oreades formed the fairy rings. Along diametric transects of each ring in most cases there were maxima in the ergosterol contents of the soil corresponding with the enhanced vegetative growth. There were also maxima in the caesium contents of the soil most of which corresponded to those of ergosterol. Site selection was an important factor in determination of the relationship between ergosterol and caesium. At a single site level of analysis a quantitative relationship between ergosterol and caesium was apparent only for one site, but overall the enhancement was significantly linearly correlated implying translocation by the fungi had occurred. No correlations between ergosterol and silver contents was observed.

Phenology and growth of Dermocybe uliginosa in a willow carr. III. Fruit-body growth and biomass production

Seasonal growth and production of individual fruit bodies were examined indirectly in permanent quadrats over 3 yr. Biomass was calculated from the ratio between average cap diameter and total fruit-body fresh or dry wt. The estimated total dry wt production in 1986 was 4·22 kg ha−1 season−1. Seasonal changes in standing live biomass, total production and total dead biomass were established using growth curves of individual fruit bodies. The relative growth and death rates were derived for total production and total dead biomass for 3 yr. The daily average biomass increments were correlated most significantly with soil, soil surface and air temperature and water-vapour pressure.

Characteristics of some species ofLaccaria, a fungal genus of significance to forestry, temperate and tropical

With an increasing interest in the use of selected fungi for the production of sheathing (ecto-) mycorrhizas by controlled inoculations, attempts were made to identify collections ofLaccaria fruitbodies from woodland and forest sites in central Scotland and at high altitudes in southern India. Although the sizes of individual fruitbodies within collections varied appreciably, it was nonetheless possible to sort the collections into 2 groups using mean sizes: one group with (i) stipes (stalks) about 7 mm long and 1 mm diam. and (ii) pilei (caps) 10 mm diam., and a second group with appreciably larger fruitbodies. The group of larger fruitbodies was found to contain collections with either 2- or 4-spored basidia; the basidia in the group of small fruitbodies were all 2-spored. Although of similar sizes, spores of the 4-spored specimens had different shapes as judged by the ratios (Q values) of spore length: spore width, separately assessed for each spore with its apiculus in view. They were either globose (Q=1·01) with 8·6 spines per 9 μm2, each spine being on average 1·01 μm tall—a description conforming toLaccaria laccata (Scop.: Fr.) Bk. and Br- or elliptical (Q=1·20) with 16·3 spines per 9 μm2, each spine being only 0·72 μm tall—a description conforming toLaccaria proxima (Boud.) Pat. The spores of the group of large fruitbodies with 2-spored basidia were globose, like those ofLaccaria laccata, but slightly larger and with more spines per unit area, 11·3 per 9 μm2, a description conforming toLaccaria ohiensis (Mont.) Sing. The spores of the group of small fruitbodies with 2-spored basidia were similarly globose but, in contrast, were appreciably larger, 10·1×9·6 μm (compared with 6·3×6·3 μm forL. laccata), with taller (1·91 μm) and fewer spines, 4·2 per 9 μm2, a description conforming toLaccaria tortilis (Bolt.) S. F. Gray. Laccaria laccata, Laccaria proxima andLaccaria tortilis were collected in Scotland;Laccaria proxima andLaccaria ohiensis in India. Contrary to expectationLaccaria laccata was found less frequently thanLaccaria proxima, the fruitbodies of both being sometimes outnumbered by those ofLaccaria tortilis in young stands ofBetula spp.

Investigation of Cell Patterning in the Asexual Fruiting Body of Dictyostelium discoideum Using Haploid and Isogenic Diploid Strains

The cell patterning (proportion of spores, stalk cells, and basal disk cells) of individual asexual fruiting bodies of haploid and isogenic diploid strains of D. discoideum was examined to test the hypothesis that the patterning mechanism is based on the 'sensing' of only a single parameter, e.g., cell volume, in dividing the aggregate into the three cell types. If cell patterning is based on sensing only a single parameter, there is no reason to predict a change in cell patterning with ploidy change, and thus haploid and isogenic diploid strains should not differ in their cell patterning. The cell patterning of each of the three pairs of haploid and isogenic diploid strains examined was different. Therefore we conclude that the cell patterning mechanism must involve at least two components not changing in the same way with change in ploidy. The cell patterning of both the haploid and the diploid strains was qualitatively similar, i.e., relationships between the three cell types were described by equations of the same form in the haploid and diploid strains. However a quantitative change in cell patterning led to an increased percentage of stalk and basal disk cells in each diploid compared to its parent haploid. The ratio of basal disk to stalk cell was also greater in the diploids than in their parent haploids. We conclude that these are general ploidy-related changes because the cell patterning of each of the three parent haploid strains was different; the average percentage of stalk cells was 11.6% for X22 (12.4% for its diploid DU162), 20.5% for NP73 (27.2% for its diploid DP62), and 24.5% for HU127 (29.1% for its diploid DU310). One possible patterning mechanism could involve a diffusible signal (s), which shows gene dosage, interacting with cell-surface molecules which we predict occupy a limited number of sites per unit area of the cell membrane. The observed change in cell patterning leading to an increased percentage of stalk cells in diploid strains is predicted from such a model involving diffusible signal interacting with cell-surface molecules.