Rhizomorph anatomy of <Emphasis Type="Italic">Ossicaulis lignatilis</Emphasis> (Tricholomatales), with special attention to its haustoria-like intrahyphal hyphae

The stout, basidiomal rhizomorphs of the agaricoid Hymenomycete Ossicaulis lignatilis are tightly woven from thin, generative hyphae, broad tubular hyphae, and broad thromboplerous hyphae that contain numerous thin, haustorialike, intrahyphal hyphae in their deuteroplasm. The plectology and cytology of the rhizomorphs and a possible role of the thromboplerous hyphae are described and discussed.     

Tomentella africana, a new species from Benin (West Africa) identified by morphological and molecular data

A common resupinate thelephoroid fungus was collected in northern Guinean seasonal forests in central and north of Benin (West Africa). The species is reminiscent of Tomentella umbrinospora with respect to the color and thickness of basidiomata and rhizomorphs, the shape of basidiospores in frontal view and the size of subicular hyphae. Both species fall phylogenetically within two clades. Based on detailed anatomical comparison (mostly of rhizomorphs and basidiospores) with the holotype of T. umbrinospora and phylogenetic analyses including ITS rDNA sequences of 40 Tomentella species, T. africana is described as a new species. Genetic distance between the newly described species and T. umbrinospora is 12.1-12.9%, based on ITS rDNA sequences. T. africana is characterized anatomically by yellow-brown thick (0.3-0.8 mm) monomitic rhizomorphs that are commonly covered by irregularly shaped thin hyphae, thin- to thick-walled subicular hyphae of two size ranges, clavate and clamped basidia of 30-60 microm and light yellow to pale brown echinulate basidiospores with irregular shape in frontal view. Detailed anatomical and molecular dissimilarities between T. africana and close species are discussed. Differences between irregularly shaped surface thin hyphae and skeletal ones are highlighted. We stress the relevance of rhizomorphal structures in the discrimination of resupinate thelephoroid fungi.     

Fungal relationships and structural identity of their ectomycorrhizae

Aproximately 5,000–6,000 fungal species form ectomyorrhizae (ECM), the symbiotic organs with roots of predominantly trees. The contributing fungi are not evenly distributed over the system of fungi. Within Basidiomycota exclusively Hymenomycetes and within Ascomycota exclusively Ascomycetes contribute to the symbiosis. Hymenomycetes play a big part, Ascomycetes a minor role; Zygomycetes only form exceptionally ECM. Responsible for ascomycetous ECM are mostly Pezizales with their hypogeous derivatives, whereas Boletales, Gomphales, Thelephorales, Amanitaceae, Cantharellaceae, Cortinariaceae, Russulaceae, and Tricholomataceae are the most important ectomycorrhizal relationships within Hymenomycetes. ECM, as transmitting organs between soil and roots, are transporting carbohydrates for growth of mycelium and fruitbodies from roots and have to satisfy the tree’s demand for water and nutrients. The latter task particularly influences the structure of ECM as nutrients are patchily distributed in the soil and saprotrophic as well as ectomycorrhizal fungi can act as strong competitors for nutrients. In focusing these requirements, ECM developed variously structured hyphal sheaths around the roots, the so-called mantles, and differently organized mycelium that emanates from the mantle, the so-called extramatrical mycelium. The mantles can be plectenchymatous consisting of loosely woven, differently arranged hyphae or they are densely packed, forming a pseudoparenchyma similar to the epidermis of leaves. The extramatrical mycelium grows either as simple scattered hyphae from the mantle into the soil or it can be united to undifferentiated rhizomorphs with a small reach or to highly organized root-like organs with vessel-like hyphae for efficient water and nutrient transport from distances of decimeters. Cystidia, sterile and variously shaped hyphal ends, possibly appropriate for preventing animal attack, in addition, can cover mantles and rhizomorphs. Although only a limited number of species could be considered, some general conclusions are possible.The genus Tuber forms needle-shaped cystidia and lacks rhizomorphs and clamps. Gomphales ECM are identified by rhizomorphs with ampullate inflations at septa of some hyphae and by oleoacanthocystidia or/and oleoacanthohyphae. Thelephoraceae reveal a great diversity of mantle structures and of extramatrical mycelium, with some additional optional characters, i.e., dark brown color, cystidia, blue granules, amyloid hyphae, or amyloid septa. Bankeraceae are mostly characterized by plectenchymatous mantles with star-like pattern and chlamydospores. Russulaceae possess smooth and hydrophilic ECM. Russula forms plectenchymatous mantles with knob-bearing cystidia, so-called russuloid cystidia, or pseudoparenchymatous mantles without cystidia. Lactarius lacks cystidia and shows laticifers within plectenchymatous or within pseudoparenchymatous mantles. The Boletales families Boletaceae, Gyroporaceae, Melanogastraceae, Paxillaceae, Rhizopogonaceae, Sclerodermataceae, and Suillaceae have the most advanced rhizomorph type, the so-called boletoid rhizomorphs, and reveal generally plectenchymatous mantles, frequently with ring-like patterns. Gomphidiaceae and Albatrellaceae provide cystidia, plectenchymatous mantles, and amyloidy; Gomphidiaceae are generally growing in ECM of Suillaceae and Rhizopogonaceae. Cortinariaceae reveal plectenchymatous mantles and undifferentiated or differentiated rhizomorphs or lack rhizomorphs at all. Cortinarius and Dermocybe are distinct by irregularly shaped, bent to tortuous ECM with many rhizomorphs, some growing over the mycorrhizal tip into the soil. Inocybe lacks rhizomorphs and its emanating hyphae are furnished by many secondary septa and prominent clamps with a hole. Rozites lacks rhizomorphs, too, and reveals a distinctly amyloid gelatinous mantle matrix. Descolea and Descomyces are covered by bolbitioid cystidia. Lastly, the genus Tricholoma forms plectenchymatous mantles and a high diversity of rhizomorphs. Some of the ectomycorrhizal features are used to hypothesize relationships at different taxonomic levels. These conclusions are compared with recently developed molecular hypotheses. Correspondence between the two types of hypotheses are evident, while some conflicts wait for a settlement.     

RHIZOMORPHS IN SOIL NOT CONNECTED WITH FUNGAL FRUITING BODIES

About half the root-like structures found in the litter of a Pinus murrayana forest were found to be in reality rhizomorphs of fungi. Conclusions based on direct observations of the soil are reinforced with culture experiments with litter in the greenhouse. Microscopic studies show a distinct structure of these rhizomorphs which distinguishes them from roots. Covered with a tight network of hyphae, they have very wide hyphae in their centers, which are named tracheodes in this paper. Although fungal rhizomorphs are well known in connection with fruiting bodies of mushrooms, the rhizomorphs in montane forest and desert occur apart from fruiting bodies and thus far have not been connected with any known mushrooms.     

Biomechanics of invasive growth by Armillaria rhizomorphs

Rhizomorphs of wood-decay basidiomycetes are root-like structures produced by the coordinated growth of thousands of hyphae. Very little is known about their development nor the way that they penetrate soils and rotting wood. In this study, we applied techniques used in previous studies on hyphae to explore the mechanics of the invasive growth process in Armillaria gallica. Growth rate measurements were made in media with different gel strengths. The osmolyte composition of rhizomorph sap was determined spectroscopically and the forces exerted by growing tips were measured using a force transducer. Cultured rhizomorphs extended at much faster rates than unbundled hyphae (3.5 mm d⁻¹ versus 1.5 mm d⁻¹) and their growth accelerated in response to increased medium gel strength (to 7.4 mm d⁻¹). Measurements of rhizomorph osmolality provided a turgor pressure estimate of 760 kPa (7.5 atm.), and spectroscopic analysis showed that this pressure was generated by the accumulation of erythritol, mannitol, and KCl. Forces exerted by growing tips ranged from 1 to 6 mN, corresponding to pressures of 40–300 kPa (0.4–3.0 atm.). Pressures exerted by extending rhizomorphs are comparable to those produced by individual vegetative hyphae. This suggests that the mechanical behavior of hyphae is similar whether they grow as unbundled cells or aggregate to form macroscopic rhizomorphs.     

Nuclear fusion,meiosis and the origin of dikaryotic hyphae in Armillariella mellea

The behaviour of nuclei during the growth and differentiation of basidiocarp primordia of Armillariella mellea (Vahl) Karst. is described. The primordial initials which arose from monokaryotic rhizomorphs were also monokaryotic. In older primordia, at the site of initiation of gill folds, multinucleate cells formed at the tips of monokaryotic hyphae and gave rise to the dikaryotic hyphae bearing clamp connections. These formed the gills of the older primordia. Cytological studies suggested that the nuclei in monokaryotic cells were diploid. In young basidial primordia haploidization occurred in the cells which were to become multinucleate prior to giving rise to dikaryotic hyphae of the gills. In mature basidia after nuclear fusion and meiosis had occurred, each of the four haploid daughter nucleic migrated into a basidiospore and then divided mitotically. One of the mitotic daughter nucleic migrated from each spore back into the basidium so that mature spores were uninucleate.Abbreviations M.T.O.C. microtubule organizing centre     

Ectomycorrhizas of Cortinarius helodes and Gyrodon monticola with Alnus acuminata from Argentina

Field ectomycorrhizas of Cortinarius helodes Moser, Matheny & Daniele (sp. nov) and Gyrodon monticola Sing. on Alnus acuminata Kunth (Andean alder, aliso del cerro) are described based on morphological and anatomical features. Ectomycorrhizal roots were sampled beneath fruitbodies of C. helodes and G. monticola from two homogeneous A. acuminata forest sites located in Tucumán and Catamarca Provinces in Argentina. C. helodes ectomycorrhizas showed a thick white to beige mantle exuding a milky juice when injured, were bluish toward the apex, and had hyphal strands in the mantle. G. monticola ectomycorrhizas showed some conspicuous features like highly differentiated rhizomorphs, inflated brown cells on the mantle surface, and hyaline and brown emanating hyphae with dolipores. Restriction fragment length polymorphism analysis of the nuclear rDNA internal transcribed spacer provided a distinctive profile for each of the collections of fruitbodies and the mycorrhizal morphotypes.     

Phylogenetic placement and anatomical characterisation of two new West African Tomentella (Basidiomycota, Fungi) species

Tomentella amyloapiculata and T. agbassaensis are described as new species within the genus Tomentella based on materials we collected in the West African, northern Guinean seasonal forests. We used a combination of anatomical characters, sequence analyses and phylogenetic inference of 71 ITS rDNA sequences to characterise the two new species. Anatomically, T. amyloapiculata is characterised by simple septate brown to dark brown, thick-walled subicular and subhymenial hyphae and triangular to slightly lobed brown basidiospores (in frontal view), with isolate aculei of 1–2 μm. Phylogenetically, T. amyloapiculata forms a sister species of T. fuscocinerea with a moderate bootstrap support of 70%. T. amyloapiculata deviates from T. fuscocinerea by 10.07–11.73% in their sequence similarities. As far as T. agbassaensis is concerned, it clusters phylogenetically together with T. bryophila with a strong bootstrap support of 99%. The species is characterised by slightly differentiated rhizomorphs with yellowish hyphae, clamped, thick-walled and yellow to dark yellow subicular hyphae and pale yellow, small basidiospores of 6–8(8.5) μm with aculei of up to 0.5 μm. Both new species deviated from each other by 11.0–11.60% with regard to the ITS rDNA nucleotides.     

Two sebacinoid ectomycorrhizae on Chinese pine

Sebacinoid fungi show a broad mycorrhizal capacity; therefore, they play a very important role in natural systems. Worldwide, fungi of Sebacinales are present under different environmental conditions and associate with diverse plant hosts, however, are hitherto poorly studied in China. Two sebacinoid ectomycorrhizae (ECM), Pinirhiza multifurcata and Pinirhiza nondextrinoidea, are described in detail morphologically and anatomically in the present study. They share a plectenchymatous outer mantle with multiply ramified hyphae in a gelatinous matrix, clampless, thin, thick-walled emanating hyphae with mostly Y-shaped ramifications and triangular inflations at the point of ramification. P. multifurcata and P. nondextrinoidea can be distinguished by thick cells in mantle layers, the ramification of emanating hyphae, the presence or absence of rhizomorphs, as well as the differing color reaction in Melzer's reagent. The putative molecular phylogenetic relationships of P. multifurcata and P. nondextrinoidea were inferred by analyses of the partial large subunit nuclear rDNA (nLSU); however, an affiliation to fungal species was not possible. This is the first report of sebacinoid ECM on Chinese pine.     

Four ectomycorrhizae of Pyronemataceae (Pezizomycetes) on Chinese Pine (<Emphasis Type="Italic">Pinus tabulaeformis</Emphasis>): morpho-anatomical and molecular-phylogenetic analyses

Morphological and anatomical characters of four ectomycorrhizae with affinities to the genera Humaria, Geopora, and Trichophaea of Pyronemataceae (Pezizomycetes, Ascomycota) on Chinese Pine (Pinus tabulaeformis) are described. The ectomycorrhizae are yellowish brown to brown, and have pseudoparenchymatous outer mantle layers and partially warty emanating hyphae with thick walls and without clamps. Intrahyphal hyphae are present, and no rhizomorphs are formed. The four ectomycorrhizae are distinguishable by differences in cell shape of outer mantle layers and the presence of cystidia. Ectomycorrhizae of a possible Humaria species (Pinirhiza humarioides) lack cystidia and have irregularly inflated cells on the outer mantle layer that are connected with thin septa. The two ectomycorrhizae showing probable affinities to Geopora species (“P. daqingensis” and “P. geoporoides”) possess row-like arranged cells in the outer mantle layer and cell heaps, and differ by the presence or absence of cystidia as well as by the structure of the inner mantle layers. Ectomycorrhizae likely having been formed by a Trichophaea species (“P. trichophaeoides”) have oval to polygonal cells and no cystidia. The possible taxa affiliations were assessed by molecular-phylogenetic analyses of the internal transcribed spacer (ITS) and partial large subunit (LSU) nrDNA. Morphological and anatomical characters are discussed against the background of the LSU phylogeny.     

Lichenizing Rhizomorphs and Thallus Development in the Squamulose Lichen Aspicilia crespiana Rico ined. (Lecanorales,Ascomycetes)

This work describes the rhizomorphs and their relation to thallus development in the squamulose lichen Aspicilia crespiana Rico ined. The rhizomorphs capture algal cells, giving rise to new squamules terminally or laterally. The thallus thus consists of a network of lichenized squamules interlinked by mycobiontic rhizomorphs. A previously proposed comparison of lichen rhizomorphs to the prothallus (hypothallus) of crustose lichens is applied and expanded upon. Other less organized prothallic structures sometimes produced by A. crespiana are also described. The importance of lichenizing rhizomorphs as an essential feature of thallus growth in this species is emphasized and a competitive role in substrate occupation and thallus expansion is suggested.     

Determination of Water, Solute and Turgor Potentials of Mycelium of Various Basidiomycete Fungi causing Wood Decay

Using thermocouple psychrometry, the water, solute and turgorpotentials of hyphae of Phallus impudicus and Serpula lacrimans,cords of P. impudicus, Phanerochaete velutina and S. lacrimansand rhizomorphs of Armillaria mellea were determined. A comparisonwas made between laboratory- and field-grown cords of P. impudicusand P. velutina. Comparison was made also between the waterrelations of the hyphae at the growing front, and hyphae ofthe more distal, basal regions. Similarly, the growing regionsof cords/rhizomorphs were compared with the older, non-extendingbasal regions of the same structures. In all cases gradientsof water and turgor potentials were found from basal, olderregions to younger, extending regions. These results are discussedin relation to the mechanism of translocation in fungi. Key words: Mycelium, Basidiomycotina, Turgor gradients, Translocation     

New Neotropical Sebacinales Species from a Pakaraimaea dipterocarpacea Forest in the Guayana Region,Southern Venezuela: Structural Diversity and Phylogeography

Pakaraimaea dipterocarpacea, a member of the Dipterocarpaceae endemic in the Guayana region, is associated with a diverse community of ectomycorrhizal (ECM) fungi. Amongst the 41 ECM fungal species detected in a 400 m² P. dipterocarpacea ssp. nitida plot in Southern Venezuela, three species belonged to the Sebacinales. We tested whether ECM anatomotype characterization can be used as a feasible element in an integrative taxonomy in this diverse fungal group, where the relevance of fruitbody morphology for species delimitation seems limited. Using a combination of ECM morpho-anatomical characterizations and phylogenetic analyses based on nuclear ITS and LSU sequences, we report three new species. The main distinguishing features of Sebacina guayanensis are the yellowish cell walls together with conspicuous undifferentiated, uniform compact (type B) rhizomorphs. Staghorn-like hyphae are characteristic of S. tomentosa. The combination of clusters of thick-walled emanating hyphae, including hyphae similar to awl-shaped cystidia with basal dichotomous or trichotomous ramifications, and the presence of type B rhizomorphs were characteristic of a third, yet unnamed species. The three species belong to three different, possibly specifically tropical clades in Sebacinales Group A. The geographic distribution of phylogenetically related strains was wide, including a Dicymbe forest in Guyana and an Ecuadorian rainforest with Coccoloba species. We show that ECM morpho-anatomy can be used, in combination with other analyses, to delineate species within Sebacinales Group A. In addition to phylogenetic information, type B rhizomorphs observed in different Sebacinales clades have important ecological implications for this fungal group. The phylogeography of Sebacinales suggests that dispersion and host jump are important radiation mechanisms that shaped P. dipterocarpacea ECM fungal community. This study emphasizes the need for more sequence data to evaluate the hypothesis that phylogeographic relationships between neo- and paleotropical ECM fungal species could be attributed to the vicariance of cross-continental hosts such as the Dipterocarpacae.     

猪苓与蜜环菌的关系

蜜环菌Armilla riella mcllea(Vahl：Ff．)Kgtst·侵入猪苓Gri[ola umbe』zd‘4(PetsFr．)PilOt)菌核,激活了猪苓菌抵御异体侵染免疫反应的本能,猪苓菌丝细胞木质化,形成与菌核表皮结构相似的隔离腔,将蜜环菌素和部分猪苓菌丝包围。在隔离腔中蜜环菌消化分隔在腔中的猪苓菌丝,另外猪苓菌丝也可侵入或附着在蜜环菌索及侵染带细胞间隙吸收其代谢产物,猪苓菌核即可萌发出新苓正常生长。当隔离腔中的猪苓菌丝被消化后,蛮环菌生活力也减弱,解体后被猪苓菌吸收利用,隔离腔变成空腔。从广义角度看,仍可把蜜环菌与猪苓菌寄生与反寄生的营养关系概括为共生关系。     

Physical Interactions of two Rhizomorph-forming Lichens with their Rock Substrate

Samples of a calcareous conglomerate rock colonized by Squamarina cartilaginea and a siliceous schist colonized by Acarospora scotica were cut and examined with SEM-backscattered electron imaging. Both species produce extensive rhizomorphs (sensu lato), whose component hyphae interpenetrated, separated, and incorporated substrate particles in the course of development. Rhizomorph expansion and contraction associated with hydration cycles could also detach adherent fragments within the substrate. In S. cartilaginea, rhizomorphs and associated hyphae also directly penetrated the calcareous substrate matrix, probably by chemical dissolution. Those of A. scotica appeared to penetrate the schist mainly by forcing their way between the fine, angular, somewhat flattened particles which comprises the substrate. The orientation of these particles influenced the form of developing rhizomorphs and the subsequent pattern of substrate exfoliation. Lichen compounds of potential biode-teriorative significance occurred within the squamules of both species but were not detectable in their rhizomorphs. Lichenized photobionts were abundant within the substrate; their developmental relationship to epilithic squamules could be demonstrated in the case of A. scotica.     

Sistotrema is a genus with ectomycorrhizal species − confirmation of what sequence studies already suggested

The ectomycorrhizal status of Sistotrema sp. is shown by morphological–anatomical and molecular identification, confirming earlier reports about Sistotrema DNA in ectomycorrhizae (ECM). For molecular identification of the ECM nuclear rDNA ITS sequences obtained from mycorrhizal root tips and fruitbodies of Sistotrema sp. were compared. Blast searches using the Sistotrema sp. sequences as query were performed in GenBank and UNITE for comparison with previously published Sistotrema sequences. The morphological–anatomical characterization of the ECM used well-established protocols for the examination of all mantle parts and rhizomorphs in different sections and views including detailed illustrations. The ECM are irregularly monopodial–pyramidal, whitish ochre to yellow ochre, and woolly. Older ones become more greyish and silvery at some patches. Diagnostic anatomical characteristics are irregularly inflated emanating and rhizomorph hyphae, ampullately inflated clamps, and the occurrence of yellow drops within the hyphae. The plectenchymatous mantle shows ring-like arranged hyphae, and a slightly gelatinous matrix. The ECM of Sistotrema sp. are compared to those of other species that form distinctly ampullate hyphae in rhizomorphs, too. The anatomically most similar ECM to those of this Sistotrema specimen are those of Hydnum repandum.     

Internal Structure and Hydraulic Conductivity of Basidiomycete Translocating Organs

Eamus, D., Thompson, W., Cairney, J. W. G. and Jennings, D.H. 1985. Internal structure and hydraulic conductivity of basidiomycetetranslocating organs.–J. exp. Bot. 36: 1110–1116. The presence in rhizomorphs of Armillaria mellea and cords ofPhallus impudicus of wide diameter hyphae (5–20 {diaeresis}m),which run for considerable distances along these linear organs,has been demonstrated. The longitudinal hydraulic conductivityof these organs has been determined experimentally and similarvalues were obtained when the hydraulic conductivity was calculatedtheoretically on the basis that the vessel hyphae were the solechannel for water movement along these organs. The experimentaldata have been discussed in relation to other data for long-distancetranslocation in basidiomycete linear organs. It is concludedthat the vessel hyphae are the main channels for turgor-driventranslocation. Key words: -Basidiomycete fungi, translocation, hydraulic conductivity     

天麻种子／原球茎和营养繁殖茎被菌根真菌定殖后的细胞分化

天麻（Gastrodia elata Bl.)种子可与紫萁小菇（Mycena osmundicola Lange),兰小菇（M.orchidicola Fan et Guo)等一类小菇属真菌共生萌发形成原球茎。侵入种皮的菌丝集结在柄状细胞外周的胚柄残迹中,首先侵入胚的柄状细胞,然后自柄状细胞侵入其他原胚细胞。原胚细胞发生功能分化,形成菌丝结细胞和消化细胞,初被菌丝定殖的原胚细胞具有消化菌丝的功能,随后,部分原胚细胞逐渐被菌丝充满,充育成菌丝结细胞。菌丝由菌丝结细胞进一步侵入消化细胞后最终被消化。由原球茎分化形成的营养繁殖茎（以下简称营繁茎）进一步被蜜环菌（Armilariella mellea(Vahl.Fr.)Karst.)定植,蜜环菌与紫箕小菇的菌丝同时存在于营繁茎中,但两菌相遇时都停止蔓延,互不交错侵染。     

Cytodifferentiation of the Seeds (Protocorms) and Vegetative Propagation Corms Colonized by Mycorrhizal Fungi

The stipecell, subepidermal parenchyma cells and inner cortical parenchyma cells were differentiated from Gastrodia elata Bl. seed and protocorm cells when they were colonized by the fungal hyphae of Mycena osmundicola Lange and M. orchidicola Fan et Guo. The hyphae aggregated in the suspensor remnant surrounding stipecell, primarily penetrated the stipecell, and then colonized the embryo of seed. Stipecell is the unique invading site of the hyphae. Subepidermal parenchyma cells containing pelotons of hyphae is also a kind of passage cells of hyphae, but, when primarily colonized by hyphae, they can degenerate a little of hyphae. The hyphae colonizing inner cortical parenchyma cells were totally degenerated, and the function of inner ocrtical parenchyma cells is digestive. The vegetative propagation corms, which differentiated from protocorms, were recolonized by Armilariella mellea (Vahl:Fr.) Karst., and the hyphae of A. mellea and M. osmundicola were found in the same cell, but there is a layer of cells uncolonized by mycorrhizal fungal hyphae. This means the two fungal species can not crisscross colonize the cell of G. elata.