Coprinus cinereus has two main types of mycelia, the asexual monokaryon and the sexual dikaryon, formed by fusion of compatible monokaryons. Syngamy (plasmogamy) and karyogamy are spatially and temporally separated, which is typical for basidiomycetous fungi. This property of the dikaryon enables an easy exchange of nuclear partners in further dikaryotic-monokaryotic and dikaryotic-dikaryotic mycelial fusions. Fruiting bodies normally develop on the dikaryon, and the cytological process of fruiting-body development has been described in its principles. Within the specialized basidia, present within the gills of the fruiting bodies, karyogamy occurs in a synchronized manner. It is directly followed by meiosis and by the production of the meiotic basidiospores. The synchrony of karyogamy and meiosis has made the fungus a classical object to study meiotic cytology and recombination. Several genes involved in these processes have been identified. Both monokaryons and dikaryons can form multicellular resting bodies (sclerotia) and different types of mitotic spores, the small uninucleate aerial oidia, and, within submerged mycelium, the large thick-walled chlamydospores. The decision about whether a structure will be formed is made on the basis of environmental signals (light, temperature, humidity, and nutrients). Of the intrinsic factors that control development, the products of the two mating type loci are most important. Mutant complementation and PCR approaches identified further genes which possibly link the two mating-type pathways with each other and with nutritional regulation, for example with the cAMP signaling pathway. Among genes specifically expressed within the fruiting body are those for two galectins, β-galactoside binding lectins that probably act in hyphal aggregation. These genes serve as molecular markers to study development in wild-type and mutant strains. The isolation of genes for potential non-DNA methyltransferases, needed for tissue formation within the fruiting body, promises the discovery of new signaling pathways, possibly involving secondary fungal metabolites.

https://mmbr.asm.org/content/mmbr/64/2/316.full.pdf

Life History and Developmental Processes in the Basidiomycete Coprinus cinereus

Publisher Summary Polyols (sugar alcohols) are widely distributed in fungi. They could serve several roles in living organisms: (1)act as carbohydrate reserves, (2) act as translocatory compounds, (3) function in osmoregulation, and (4) in coenzyme regulation and storage of reducing power. This chapter describes several enzymes that are concerned with polyol metabolism in fungi. These include Glycerol dehydrogenase (NAD + ), Glycerol-3-phosphate dehydrogenase (NAD + ), Xylitol dehydrogenase (NAD + ), Mannitol-1-phosphate dehydrogenase, Polyol dehydrogenase (NADP + ), Mannitol dehydrogenase (NAD + ), Glyceroldehydrogenase (NADP + ), Ribitol-5-phosphate dehydrogenase (NADP + ), Mannitold ehydrogenase(NADP + ), Glycerophosphate dehydrogenase, Glycerol kinase, Mannitol kinase, Mannitol-1-phosphatase, Sorbitol (glucitol) dehydrogenase, and Glycerol oxidase. A number of enzymes have relatively high K m , values for their substrates and a high pH optimum for the oxidation of polyols, which is likely to be a consequence of the buffer more effectively consuming protons at such pH values. It is conceivable that these particular enzymes are membrane-bound. The groups to which the various fungi belong are identified and designated as—namely, Mastigomycotina (M), Zygomycotina (Z), Ascomycotina (A), Deuteromycotina (D) and Basidiomycotina (B).

Polyol metabolism in fungi

Developmental biology of sclerotia

ion between fibre lignin and laccase in qualitative difference in temporal phases than laccase does alone. Resulting distinguished lignin modifications may have consequences for subsequent fibre behaviour (Barsberg 2002). Lund & Felby (2001) applied a range of mediators in laccase-modification of spruce and pine fibres and found ABTS and PPT (phenothiazine-10-propionic acid) to be effective in enhancing wet tensile strength of paper handsheets made from the pulp. Similar results were obtained with ABTS by Elegir et al. (2005, 2007). Treatment of fibres with laccase and gallic acid were also reported to change wet tensile strength (Chandra et al. 2004b), indicating that laccase-mediator system can influence properties of the fibre surfaces. Various mediators are therefore currently tested in MDF production with laccase in order to achieve higher reactivity between laccase and lignin and better board properties (Müller et al. 2006). The unfortunately limited availability of cheap and non-toxic mediators is of course a restricting factor in such approaches (Rochefort et al. 2004, Morozova et al. 2007). So far, in laccase-mediated bleaching of lignocellulosic fibres 1-hydroxybenzotriazole and the lignin-derived phenols acetosyringone and syringaldehyde acid have been positively tested as mediators whereas negligible effects were seen with p-coumaric acid (Ibarra et al. 2006, Camamero et al. 2007, Gutiérrez et al. 2007). Oppositional ABTS-mediated depolymerisation and polymerisation effects on kraft lignin samples (González Arzola et al. 2006, Hernández Fernaud et al. 2006) imply that the doses and times of mediators and enzymes applied have to be expected to play an important role in activating of fibre material. In line with this, dosages of 4-hydroxybenzoic acid were most influential in laccase-mediated modification of paper pulp (Chandra et al. 2004a). Further to applications of mediators to improve mechanical properties by laccase action, recent studies suggest that a successive xylanase and laccase treatment with or without mediators might also be useful in efficiently modifying fibre surfaces at least in paper production. As the gallic acid mediator treatment, successive xylanase-laccase treatment has been reported to increase the wet tensile strength of paper (Chandra & Raugaskas 2005, Kapoor et al. 2007). 2-component adhesives based on lignin and enzymes In the wood composite industry, addition of lignosulphonates (spent sulphite liquor) or kraft lignins from sulphate pulping, to conventional PF resins is targeted at replacing parts of the phenol component made from petrochemicals (e.g. see Roffael & Rauch 1971, Shen 1974, Nimz 1983, Ayla & Nimz 1984, Danielson & Simonson 1998a,b, Tejado et al. 2007; further reading in Chapter 16 of this book). Formaldehyde from the PF resin may act in such mixtures as a cross-linker between the reactive sites of the technical lignins and the synthetic phenol binder (Kuo et al. 1991, Vázquez et al. 1999, El Mansouri & Salvadó 2006, 2007). As first

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Wood production, wood technology, and biotechnological impacts

Translocation of solutes in fungi.

Summary
An interpretation of carpophore morphogenesis is presented which is derived both from the literature and from original observations. Cultured material of Coprinus cinereus (also called C. macrorhizus and C. lagopus) has been studied using biochemical assays together with light-, scanning- and transmission electron microscopy to provide details of histology and the levels and distribution of protein, glycogen and NADP-linked glutamate dehydrogenase during the course of development of stipe and cap. Initially, aggregates of hyphae form primordia which subsequently develop into mature carpophores. During stipe development glycogen deposition is at first restricted to cells forming a cup-shaped mass in the stipe base, but very early in primordium development this deposit is depleted and glycogen accumulates in the gills, particularly the subhymenium, where it probably serves as a reserve material for the later stages of cap development. The distribution of cytochemically detectable protein differs from that of glycogen in that the former initially accumulates in the upper regions of the primordial stipe and in the gill hymenium. The stipe showed no conspicuous change in its content of protein during development although in the cap the fraction of the dry wt represented by protein increased substantially. Primordial stipes are composed of overlapping cells of hyphal dimensions with dense cytoplasm and small vacuoles. Stipe development depends on cell enlargement, this seeming to be biphasic; an initial increase in volume being attributable to an increase in cell diameter to give an undifferentiated dikaryotic central region and a differentiated multi-nucleate cortex. Stipe growth depends on reallocation of cellular components, no one reserve material being identifiable as of prime importance although a few simple sugars do appear to be correlated with the osmoregulatory activity connected with the large scale uptake of water involved in stipe elongation. In the primordium cap the subhymenium is an open tissue of interwoven hyphae, the cells containing large accumulations of glycogen. The hymenium is formed from dikaryotic branches of the subhymenial hyphae to become an organised layer of hyphal tips. Subsequently, although the subhymenial hyphae remain as such, the hymenial cells become inflated. The paraphyses come to form a pavement of appressed and interlocked cells each containing a large central vacuole. Basidia are only slightly enlarged and contain dense cytoplasm with few vacuoles; they contrast with the much extended and inflated cystidia. Despite their inflation, all three cell types still show continuity with the subhymenial hyphae. During cap expansion the major inflationary force is paraphyseal enlargement but as the gill lamellae are removed by autodigestion further cell inflation in the pileal flesh enables it to assume a supportive role. In the earlier stages there is some correlation between declining glycogen content of the cap and increasing activity of NADP-linked glutamate dehydrogenase. It is suggested that cap expansion is driven osmotically and that at least some of the osmotically active materials are synthesised through the urea cycle. At first this activity could be supported by glycogenolysis and amination but later on substrates may be provided by autodigestion of spent gill tissues. It is concluded that cap development is regulated by a metabolism quite distinct from those of either the parental mycelium or the stipe, and that the fundamental metabolic changes occurring throughout carpophore development are orchestrated by light. As carbohydrate nutrients in the medium approach exhaustion suppression of mycelial morphogenesis into hyphal aggregates is lifted, but the subsequent switch from the vegetative pathway of sclerotium development to carpophore formation is normally dependent on illumination with low intensity blue light. Growth then becomes polarized to form a presumptive pileus and glycogen is mobilized from the surrounding mycelium to accumulate at the base of the stipe. Receipt of a second illumination inhibits further growth of the stipe base and causes glycogen reserves to be translocated to the cap. Glycogen is utilized in the cap to produce glycolytic intermediates, allowing regulation of many aspects of metabolism by catabolite concentration and contributiong to the diverse syntheses required for spore formation and dissemination.

Morphogenensis of the carpophore of coprinus cinereus

SUMMARY
Aerial sclerotia originated from intercalary cells of aerial hyphae. Initially only a single cell was involved. Repeated branching from the initiation point formed the sclerotium initial which was a more or less spherical mass of undifferentiated, radially arranged cells. Accumulation of glycogen in cells towards the centre of the initial marked the commencement of maturation. Cells of the central (medullary) region went through a differentiation process which involved first a heavy accumulation of glycogen; the glycogen was then mobilized, its reduction in concentration being exactly correlated with the formation of a thick, hyaline, secondary wall. As the medulla developed, differentiation of localized areas of cells just within the margin of the initial occurred to form the protective rind layer. Wall thickening in rind cells was not preceded or accompanied by glycogen accumulation. Strains which failed to produce sclerotia behaved as stable variants, sclerotium non-production segregating as a single gene. Four such genes were recognized and some linkage information obtained.

Morphogenesis of aerial sclerotia of coprinus lagopus

SUMMARY
Sclerotia were formed in both aerial and submerged parts of the mycelium. In addition a layer of cells with pigmented thick walls (called brown matting) which differentiated at the air/agar interface was interpreted as an aspect of sclerotial behaviour since it was regularly formed by strains which produced submerged sclerotia and was composed of cells of similar structure to those of the outermost layer of the submerged sclerotium. Apart from producing sclerotia and oidiospores the cells of the aerial mycelium remained undifferentiated. In contrast, cells of the submerged mycelium, though initially indistinguishable from those of aerial hyphae, became individually differentiated within about 5 days of growth producing two further novel cell types; inflated cells containing glycogen, and hyaline thick-walled cells. Submerged sclerotia were pale brown in colour, irregularly shaped and about 0.5–1.0 mm in diameter. The only structure which differentiated the submerged sclerotium from the submerged mycelium was the outer rind, a layer of cells with thick, pigmented walls. The central (medulla) region contained the same cell types in the same frequencies as the general submerged mycelium. In sharp contrast the aerial sclerotia were highly organized structures composed of distinct and compact tissues. Mature aerial sclerotia were dark brown to black spheroidal structures up to 0.5 mm in diameter. An outer layer of dead and moribund hyphae surrounded the main body of the sclerotium which was bilayered with an outer rind and inner medulla. The rind was multilayered and consisted of small cells with thick pigmented walls; intercellular spaces were cuticularized. The medulla was a closely packed tissue composed predominantly of hyaline thick-walled cells of the same type as were encountered in the submerged mycelium.

Structure of aerial and submerged sclerotia of coprinus lagopus

Summary
The NAD- and NADP-linked glutamate dehydrogenases were detected in frozen sections of carpophore tissues by means of tetrazolium salt. Material at all stages of development was examined. From the earliest stages NAD-glutamate dehydrogenase was uniformly distributed in the basidial cells of the hymenium, and as the carpophore developed an increasing proportion of cells of the subhymenium came to express enzyme activity. The NADP-glutamate dehydrogenase (NADP-GDH) was initially limited to basidial cells in isolated patches of the hymenium. As development proceeded the proportion of basidia exhibiting NADP-GDH activity increased, as did the proportion of subhymenial cells showing this enzyme activity. No NADP-GDH activity was detectable in sections of stipe tissue.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.1979.tb07570.x

R. D. Butler

Papers

Morphogenensis of the carpophore of coprinus cinereus

Morphogenesis of aerial sclerotia of coprinus lagopus

Structure of aerial and submerged sclerotia of coprinus lagopus

Cytochemical localization of glutamate dehydrogenases during carpophore development in coprinus cinereus

Thick-walled sclerotial medullary cells in Coprinus lagopus