Most ciids (Ciidae) are strict fungivores specialized on fruit bodies of wood-rotting fungi. The Ciidae includes both specialist and generalist species. Recent evidence suggests that ciids locate and discriminate their potential hosts based mainly on fungal odours. In this study, we investigated the field distribution of ciids in a local woodland near Bath, U.K. We also evaluated experimentally the behavioural responses of ciids to host and non-host fungi in an olfactometer, and explored potential differences in putative aroma compounds in host fungi.Our field data showed that Octotemnus glabriculus, Cis boleti and Cis nitidus have preference for one host species. whereas C. bilamellatus has no preference. The experimental evidence was in accordance with the held observations. The specialists O. glabriculus, C. boleti and C. nitidus were specifically attracted to odour compounds of their preferred host fungi: Coriolus versicolor for the first two beetles and Ganoderma adspersum for the latter one. By contrast, the generalist C. bilamellatus was attracted to odours from C. versicolor, G. adspersum and Piptoporus betulinus.The evidence from this and other published studies suggest that ciids depend mainly on fruit body odours for location and discrimination of their host fungi. In accordance with this, we observed differential behavioural responses of ciids to aroma compounds of host and non-host species.

On the basis of the evidence that insect fungivory has the potential to affect fungal reproductive fitness, we investigated the effects of two specialist ciid beetles (Octotemnus glabriculus and Cis boleti) on the reproductive potential of their host fungus, Coriolus versicolor. We found, from field data, a negative correlation between the number of individuals of O. glabriculus inhabiting C. versicolor fruit bodies and the percentage of the fungal spore‐producing surface (hymenium) that was functional. By contrast, the number of C. boleti inhabiting C. versicolor fruit bodies did not correlate with the percentage of functional hymenium. Experimentally, O. glabriculus and C. boleti reduced the reproductive potential of C. versicolor by 58% and 30%, respectively, whereas the combined trophic activity of both beetles caused a reduction of 64%. This latter effect was not significantly different from that caused by O. glabriculus alone. These findings disagree with previous assertions that insect fungivory on fruit bodies has only neutral effects on fungal fitness. We conclude that in the short‐term, fungivory by ciids significantly decreases the area of functional hymenium of C. versicolor and is likely to reduce fungal reproductive fitness. Within this perspective the evolution of certain fungal characteristics (i.e. chemical composition, consistency and phenology) can be interpreted as being driven by fungivory.

The ciid beetles Octotemnus glabriculus and Cis boleti exploit different developmental stages of fruit bodies of their preferred host fungus Coriolus versicolor . Larvae of the smaller beetle, O. glabriculus , mainly use young, expanding, fruit bodies; adults of O. glabriculus are predominantly found in young fruit bodies. By contrast, adults and larvae of the larger beetle, C. boleti , are prevalent in fully developed fruit bodies of C. versicolor . Because fruit bodies of most genets emerge during spring and early summer and mature by autumn, O. glabriculus and C. boleti breed in separated seasons. Adults and larvae of O. glabriculus are abundant in spring and early summer. By contrast, the number of adults and larvae of C. boleti increases gradually from late spring to summer and peaks in autumn. We conducted a field experiment that suggests that the phenological dynamics of C. versicolor fruit bodies drive the separation of breeding seasons between O. glabriculus and C. boleti . Additionally, laboratory experiments revealed that O. glabriculus and C. boleti have differential behavioural responses to odour compounds from young and mature fruit bodies of C. versicolor . We conclude that age‐related changes in the chemical composition of fruit bodies may allow O. glabriculus and C. boleti to discriminate among C. versicolor , thus providing a mechanism for the partitioning of the resource.

Fungal mycelia can alter their organizational pattern in such ways as to produce alternative phenotypes. The latter allow mycelia to explore for, assimilate, conserve, and redistribute resources in spatially and temporally heterogeneous niches. It is suggested that mycelia produce alternative phenotypes by operating as nonlinear (feedback regulated), hydrodynamic systems with indefinitely expandable (indeterminate) boundaries. As such, mycelia can vary the resistances of hyphal envelopes to deformation and passage of molecules, and of hyphal interiors to displacement of contents, in accord with fortuitous local circumstances. Within the mycelial protoplasm are populations of nuclei and mitochondria. If disparate in genetic content or expression, these organelles can form diverse and unstable relationships that both influence and are influenced by metabolic processes affecting the hydraulic resistances of hyphae. Some of these processes may be autocatalytic, involving the generation, association and dissociation of free radicals and reactive oxygen species. Once initiated, such processes are beyond immediate genetic control. Fungal mycelia therefore epitomize the complex interplays between adaptive (genetic) and nonadaptive (organizational) processes that regulate the short term versatility and long term evolutionary divergence of indeterminate systems. Key words: epigenetics, mycelial development, networks, niche, nonlinearity, speciation.

Progressive changes in the quantity and type of hydrophobic metabolites, notably phenolic and quinonic compounds, were detected in extracts from pure cultures of Hypholoma fasciculare and Phlebia radiata grown on 3% malt agar. The changes were particularly marked when the production of coloured aerial mycelium intensified following the cessation of colony extension, and were accompanied by the formation of crystals and amorphous precipitates in extracts from H. fasciculare and P. radiata respectively. Some of the changes could occur autonomously, in stored extracts. Interaction with other fungi, or exposure to 2,4-dinitrophenol, which had similar effects to interactions on patterns of mycelial emergence, resulted in a sharp reduction in extractable aromatic metabolites from H. fasciculare and no crystals or precipitates were formed. However, when H. fasciculare and Peniophora lycii interacted in the presence of cetyl trimethyl ammonium bromide, complex changes in mycelial morphogenesis and substantial quantitative and qualitative shifts in production of extractable metabolites occurred.These observations suggest that a complex relationship exists between mycelial morphogenesis, the synthesis and release of aromatic metabolites, and the activity of phenol-oxidizing enzymes.

In Phlebia radiata, dense, localized zones of salmon- to orange-coloured, septate hyphae emerge from the mycelium in response to encounters with other fungi and the bacterium Bacillus subtilis on malt agar-based media. In monoculture such emergent growth develops more gradually and homogeneously, and is accompanied by the accumulation of four hydrophobic aromatic metabolites in culture extracts.Production of emergent mycelium could be induced in P. radiata by a wide variety of factors, including culture extracts from B. subtilis and compounds known to affect mitochondrial metabolism or phenoloxidase activity. In particular, the uncoupling agent, 2,4-dinitrophenol, when supplied heterogeneously, induced patterns of localized emergence strongly resembling those induced by biotic interactions. Induction of emergent development was associated quantitatively with shifts in phenoloxidase activity.

Conference Article| May 01 1994 Induction of metabolic and morphogenetic changes during mycelial interactions among species of higher fungi Alan D. M. Rayner; Alan D. M. Rayner ‡ *School of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K. ‡To whom correspondence should be addressed. Search for other works by this author on: This Site PubMed Google Scholar Gwyn S. Griffith; Gwyn S. Griffith *School of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K. Search for other works by this author on: This Site PubMed Google Scholar Howard G. Wildman Howard G. Wildman †Department of Natural Products Discovery, Glaxo Group Research Ltd., Greenford Road, Greenford UB6 0HE, U.K. Search for other works by this author on: This Site PubMed Google Scholar Author and article information Publisher: Portland Press Ltd Received: December 10 1993 Online ISSN: 1470-8752 Print ISSN: 0300-5127 © 1994 Biochemical Society1994 Biochem Soc Trans (1994) 22 (2): 389–394. https://doi.org/10.1042/bst0220389 Article history Received: December 10 1993 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn Email Cite Icon Cite Get Permissions Citation Alan D. M. Rayner, Gwyn S. Griffith, Howard G. Wildman; Induction of metabolic and morphogenetic changes during mycelial interactions among species of higher fungi. Biochem Soc Trans 1 May 1994; 22 (2): 389–394. doi: https://doi.org/10.1042/bst0220389 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search Keywords: DNP, 2,4-dinitrophenol This content is only available as a PDF. © 1994 Biochemical Society1994 Article PDF first page preview Close Modal You do not currently have access to this content.

summaryRatios of nuclear genotypes observed in conidia from heterokaryotic strains of Heterobasidion annosum (Fr.) Bref., obtained from pairings between sympatrically derived, sib‐related and non‐sib‐related homokaryons, commonly deviated from 1:1. Ratios were temporally stable, and the genotypes examined could be ranked in a strict dominance hierarchy, linked both to the relatedness of the association partners and to the growth rates of the parental homokaryons. Parental homokaryons and sibrelated heterokaryons produced conidia with a mean number of nuclei of about two, whereas non‐sib‐related‐d heterokaryons produced conidia that were predominantly uninucleate. Moreover, whereas conidia containing more than one nucleus germinated most rapidly when derived from homokaryons or sib‐related heterokaryons, uninucleate conidia germinated more readily if derived from non‐sib‐related heterokaryons. In a study of naturally occurring heterokaryons, distribution patterns of the number of nuclei in conidia were found to be similar to those of the homokaryons. The possible interpretation of these findings in terms of inter‐nuclear genomic conflict is discussed.

Strains of the basidiomycete fungi Stereum hirsutum from the USSR and Stereum complicatum from the eastern USA were interfertile, yielding viable, variable, meiotic progeny. However, interactions between paired homokaryotic mycelia of these species were unstable, yielding a uniform mycelial mat on the S. complicatum side, but a macroscopically heterogeneous mycelium on the S. hirsutum side. Hyphal tips excised from the interactions gave rise to colonies identifiable as one or other of the progenitor strains or two non-progenitor types (C-types and H-types). C-types were all morphologically similar to one another and resembled the S. complicatum progenitor except in being inaccessible to nuclear migration and in exhibiting a light-induced phenotypic switch. They could be isolated from both sides of interactions and were somatically compatible with one another. H-types were only isolated from the S. hirsutum side of interactions and had a range of morphologies, generally similar to the S. hirsutum progenitor. Pairings between H-types, and between H-types and C-types sometimes resulted in pigmented interaction zones due to somatic incompatibility. Single, dual and minisatellite DNA probes were used to investigated restriction fragment length polymorphisms in progenitor and derivative strains. Nuclear, but not mitochondrial DNA from both species was detected in all non-progenitor strains obtained from beyond the interaction interface. However, whereas S. complicatum-specific nuclear sequences were consistently present, the distribution of S. hirsutum-specific sequences varied, and was partly correlated with possession of H-type morphologies.

Hyphal and mycelial interactions within progeny sets of single basidiospore isolates derived from Heterobasidion annosum fruit bodies from various parts of the northern hemisphere were studied microscopically using microculture chambers and with pairing tests, respectively. The behaviour within different sets was highly variable with respect to mating, nuclear exchange, morphogenetic patterns and somatic rejection responses. Evidence was obtained that rapid nuclear migration can occur between certain strains. An unusually large proportion of pairings (84%) produced stable heterokaryons, as determined from back pairings with original homokaryons, of which 54% possessed clamp connections and 46% did not. Studies of isozyme patterns of pectinases of one selected pairing confirmed the presence of clampless heterokaryons. The genetic control of heterokaryosis is complex, with subsidiary systems being superimposed on those which govern formation of clamp-connections and mycelial morphogenesis. The implications of these findings in understanding gene flow within and between natural populations of H. annosum are discussed.

The mycelium of higher fungi is portrayed as a developmentally versatile collective in which an initially dendritic pattern of branching is converted, by hyphal anastomosis, into a communication network. Spatial and functional patterns in the mycelium depend on the establishment of gradients allowing flow of protoplasmic resources and organelles via radial or tangential routes between source and sink regions. Anastomosis between genetically different mycelia of the same or closely related species sets the stage for varying outcomes of genomic interplay between nuclear and mitochondrial populations. These outcomes range from the stable ‘merger’ of fully compatible basidiomycete matings, through various unstable associations culminating in genomic takeover, degeneracy or complex phenotypic emergence, to the mutual rejection characteristic of a somatic incompatibility response.

Three separate collections were made in southern England of Phanerochaete magnoliae forming hydnoid hymenial surfaces through the tubes of Datronia mollis basidiomes. Isolates of P. magnoliae exhibited unusual patterns of development and interaction with other fungi. Germinating basidiospores produced an extensive, sparsely branched, rapidly extending and fully coenocytic mycelial phase with a low fractal dimension. This phase was followed by events of septation, lateral branching, anastomosis, hymenium formation and autolysis in a strongly ordered ontogenetic sequence. These events were correlated with changes in constitutive and inducible laccase and tyrosinase activity. P. magnoliae also had a non-outcrossing breeding strategy and was able specifically to replace colonies of D. mollis without producing dense invasive mycelium.

Pairings between certain combinations of homokaryotic strains of Stereum spp. give rise, following immigration of non-self nuclei, to extensive zones of appressed, degenerative mycelium. Aerial, crystalline filaments, up to 35 m wide and ⩾ 6 cm long, emerge from this mycelium at localized foci which appear to act as sinks for mycelial resources. The filaments are shown to be the bicyclic tertiary alcohol, ( + )-torreyol. The larger filaments are aggregations of elongated sub-units which generally spiral steeply around the longitudinal axis and extend independently and apically, even when exposed to the atmosphere. Re-crystallization of (+)-torreyol from organic solvents or by sublimation results in patterns resembling those of mycelial morphogenesis in both shape and size. Novel proteins are produced in the degenerate mycelium, in which the combination of nuclear but not mitochondrial DNA restriction fragment length polymorphisms from both progenitors is demonstrated. Subcultures and basidiospore-derived progeny from the degenerate mycelium exhibit marked developmental variation and instability.

Individual mycelial genotypes (genets) of Hymenochaete corrugata are able to traverse the canopies of coppice-grown hazel, Corylus avellana, by producing sclerotized mycelial pads which bridge between and bind together contiguous stems from the same and different stools. The pads may also allow attachment to other trees, e.g. elm (Ulmus sp.), climbers, e.g. Clematis vitalba and fallen leaves. Underlying this hitherto unsuspected means of aerial spread in temperate woodland is the ability of the fungus to oscillate between distinctive modes of mycelial development, concomitant with production of melanized pseudosclerotial plates.

Outcrossing populations of the Coniophora puteana complex had a multiallelic unifactorial (bipolar) homogenic incompatibility (mating) system regulating the emergence of a secondary mycelium (stable mating-type heterokaryon) between paired single basidiospore-derived strains (homokaryons). Emergence of the secondary mycelium involved a switch to fast-effuse development at the interaction interface, probably dependent on resources redistributed from progenitor hyphae whose extension was arrested. This switch was preceded by a short phase of nuclear migration associated with eccentric erosion of dolipore septa, accompanied by formation of lateral bulges superficially resembling clamp connexions. The secondary mycelium was sometimes delimited from progenitor mycelium by a brown zone. Pairings between genetically different secondary mycelia invariably resulted in such zones, due to somatic incompatibility. Pairings between homokaryons from Europe and the U.S.A. revealed four breeding units. There was no clear correlation between breeding ability and geographic origin, angiospermous or gymnospermous hosts, but one breeding unit was solely from Britain and another was from a single domestic collection.