Immunological detection of the fungal parasite,Pythium sp.; the causative organism of red rot disease in Porphyra yezoensis

The red rot disease of Porphyra yezoensis Ueda (Rhodophyta) is caused by a parasitic fungus, Pythium sp. To facilitate the detection of this pathogen in infected thalli of P. yezoensis, polyclonal and monoclonal antibodies were prepared. Antibodies were raised against antigen prepared from an isolate of fungal hyphae obtained from red-rot infected thallus of P. yezoensis from Aichi Prefecture. Polyclonal antibody was obtained from the antisera of immunized rabbits. Monoclonal antibody was obtained from the culture supernatant of a hybridoma which had been established by cell fusion between a myeloma cell line and spleen cells of immunized mice. Hyphae were detected by means of indirect fluorescent antibody technique. Titers of polyclonal antibodies obtained were too low to recognize fungal hyphae that had penetrated the thalli of P. yezoensis; however, monoclonal antibody was useful for the detection of fungi that had penetrated algal thalli. The monoclonal antibody was specific for the Pythium sp. from red-rot infected thalli of P. yezoensis from Saga (western Japan) and from Aichi Prefectures (central Japan), but was ineffective for infections from Miyagi Prefecture (northern Japan). It is evident, therefore, that Pythium sp. can give rise to immunologically distinct groups of red rot disease. Based on chemical and enzymatic treatments, the antigenic determinant appeared to localize on the sugar chains of glycoconjugates or the polysaccharides of the hyphal cell wall.     

An unusual microfungus in a fungal spore from the Lower Devonian Rhynie chert

Abstract: A new fossil microfungus, Kryphiomyces catenulatus gen. et sp. nov., occurs as an endobiotic mycelial thallus in a large spore of a glomeromycotan fungus from the Lower Devonian Rhynie chert. The thallus consists of branched (?pseudo‐)septate hyphae with numerous catenulate swellings. Some hyphal tips produce spherical reproductive structures or propagules. Hyphal morphology in K. catenulatus is reminiscent of that in certain extant Hyphochytridiomycota, Chytridiomycota, and even Ascomycota, but specific diagnostic features that allow assignment of the fossil to modern groups are absent. The discovery of this interfungal association broadens our knowledge about the diversity of microfungi and their intricate associations in early continental ecosystems.     

QUANTITATIVE VARIATION IN VULPINIC AND PINASTRIC ACIDS PRODUCED BY TUCKERMANNOPSIS PINASTRI (LICHEN-FORMING ASCOMYCOTINA,PARMELIACEAE)

Tuckermannopsis pinastri is a lichen species found commonly on rocks and tree branches in boreal and alpine habitats in the northern United States. Members of this species produce three yellow-pigmented phenolic compounds: usnic, pinastric, and vulpinic acids. The objective of our study was to quantify the variation in concentration of the latter two of these compounds in relation to substrate factors, chlorophyll content, and thallus size. Using high-performance liquid chromatography, we analyzed 120 thalli of T. pinastri collected randomly from a single large population located at Spruce Knob, West Virginia. Although individuals were sampled from both tree and rock substrates that differed markedly in light intensity, these environmental factors were not correlated with observed variations in vulpinic or pinastric acid concentrations. Instead, compound concentrations were correlated most closely with thallus size, with small rather than large thalli having the highest concentrations of the two compounds. Small thalli did not have higher concentrations of chlorophylls than large thalli, however, which suggests that the rate of production of secondary compounds by the fungus in T. pinastri is independent of algal biomass. Inasmuch as lichen secondary compounds serve a defensive role against microorganisms and herbivores, our results suggest that small, juvenile thalli are better defended than more mature thalli.     

Parasitierung ewes im freiland aufgefundenen intersexes von Aedes (Ochlerotatus) communis de geer (Insecta,Culicidae) durch einen pilz der ordnung blastocladiales

Zusammenfassung Im Leithagebirge, im Osten Österreichs, wurde ein Intersex von Aedes (Ochlerotatus) communis gefunden, dessen Abdominalsegmente Tausende von Sporangien eines Pilzes der Ordnung Blastocladiales enthalten. Es ist mit Sicherheit anzunehmen, daß die Ausbildung der Intersexualitdt eine Folge der Mykose darstellt.Die morphologischen Charakteristika des Intersexes und die Sporangien des Parasiten werden beschrieben und abgebildet. Die Art des durch den Parasiten ausgelösten Wirkungsmechanismus wird diskutiert, wobei die Literatur über Intersexualität bei Culiciden und anderen Insektengruppen besprochen wird.

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Summary In the Leithagebirge, in the east of Austria, an intersex of Aedes (Ochlerotatus) communis was found, the abdominal segments of which contain thousands of sporangia of a fungus of the order Blastocladiales. It can be assumed with certainty that the intersex was caused by the parasite.Morphological details of the intersex as well as of the sporangia of the fungus are described and pictured. The mode of action induced by the parasite and pertinent literature are discussed.

     

Atkinsiella awabi sp. nov. isolated from stocked abalone,Haliotis sieboldii

A fungal disease in the abalone,Haliotis sieboldii, stocked in Yamaguchi Prefecture, Japan, showed external signs of infection of tubercle-like swelling on the mantle and melanized lesions on the peduncle. The fungus responsible was isolated by inoculating materials taken from the lesions onto PYGS agar with streptomycin sulphate and ampicillin, and incubation at 20°C. For morphological observation and spore formation study, the fungus was transferred respectively into PYGS broth and sterilized artificial seawater and incubated at 20°C. Resulting, hyphae were stout, irregular, branched, 16–140µm diam, sporadically consisting of dense cytoplasmic swollen hyphae. Sporangia were formed through the formation of septa and lateral or terminal discharge tubes which were wavy or coiled. Zoospores were pyriform, biflagellate and diplanetic. The encysted spore generally developed a hairlike filament with globular enlarged tip in PYGS broth. Direct germination without filament formation also occurred occasionally. This fungus was identified as belonging to the genusAtkinsiella, and was designatedAtkinsiella awabi sp. nov. The fungus was exclusively a marine fungus and grew best in shrimp extract medium at 20°C. Five chemicals were tested for their effects against fungal zoospores.     

Fungal sporocarps from the Carboniferous: An unusual specimen of Traquairia

Small spherical structures commonly termed sporocarps are widespread elements in Carboniferous permineralized peat. While sporocarps today are generally interpreted as fungal, their precise systematic affinities largely remain unknown. A specimen of the sporocarp-type Traquairia from the Lower Coal Measures (Lower Pennsylvanian) of Great Britain demonstrates a heretofore unknown feature in the form of a preformed aperture from which emerges a fascicle of radially oriented structures that are constricted sub-distally; transverse septa are present in the constricted areas of some of the structures. The outgrowths are morphologically similar to conidiophores bearing terminal conidia of certain extant fungi in the order Entomophthorales, and thus might suggest affinities of Traquairia with the Zygomycota. Alternatively, the outgrowths might represent sporulating hyphae of a parasitic or saprotrophic blastocladalean fungus or a peronosporomycete that used Traquairia as a nutrient source.     

Rates of photosynthesis of two lichens and of their isolated algal components

Abstract

The rate of photosynthesis of two lichen species (Peltigera leucophlebia and Ramalina farinacea) was found to be 30 to 40% that of spinach leaf dises and 20% that of the free-living alga Chlorella when the results were expressed on a per mg chlorophyll basis. When the algae were isolated from the thalli, the rate of photosynthesis per mg chlorophyll increased for Ramalina farinacea and decreased for Peltigera leucophlebia. Product analysis indicated that the products of photosynthesis depended on the association of the alga with the fungus: algae isolated from the thalli showed a «shift» in products from sugars and sugar alcohols. to compounds such as organic acids. The results suggest that a symbiotic relationship with a fungus alters both the rate and products of algal photosynthesis.     

Hyphosphere interactions between Rhizophagus irregularis and Rahnella aquatilis promote carbon–phosphorus exchange at the peri-arbuscular space in Medicago truncatula

Arbuscular mycorrhizal (AM) fungi form a continuum between roots and soil. One end of this continuum is comprised of the highly intimate plant–fungus interface with intracellular organelles for nutrient exchange, while on the other end the fungus interacts with bacteria to compensate for the AM fungus' inability to take up organic nutrients from soil. How both interfaces communicate in this highly complex tripartite mutualism is widely unknown. Here, the effects of phosphate-solubilizing bacteria (PSB) Rahnella aquatilis dwelling at the surface of the extraradical hyphae of Rhizophagus irregularis was analysed based on the expression of genes involved in C-P exchange at the peri-arbuscular space (PAS) in Medicago truncatula. The interaction between AM fungus and PSB resulted in an increase in uptake and transport of Pi along the extraradical hyphae and its transfer from AM fungus to plant. In return, this was remunerated by a transfer of C from plant to AM fungus, improving the C-P exchange at the PAS. These results demonstrated that a microorganism (i.e., a PSB) developing at the hyphosphere interface can affect the C-P exchange at the PAS between plant and AM fungus, suggesting a fine-tuned communication operated between three organisms via two distantly connected interfaces.     

Oldest fossil basidiomycete clamp connections

A rachis of the fossil filicalean fern Botryopteris antiqua containing abundant septate hyphae with clamp connections is preserved in a late Visean (Mississippian; ~330 Ma) chert from Esnost (Autun Basin) in central France. Largely unbranched tubular hyphae pass from cell to cell, but may sometimes produce a branch from a clamp connection. Other clamp-bearing hyphae occur clustered in individual cells or small groups of adjacent host cells. These hyphae may be tubular, catenulate with numerous hyphal swellings, or they may display a combination of both. The Visean hyphae with clamp connections predate Palaeancistrus martinii, the heretofore oldest direct fossil evidence of Basidiomycota, by some 25 Ma.     

Ultrastructure of Ascodichaena rugosa on beech bark

Ascodichaena rugosa Butin is a corkinhabiting fungus, found frequently on the bark of Fagus sylvatica L. The hyphae of the fungus are distributed solely in the phellem cells, stopping their growth in the last-formed cork cell layer. The cell to cell invasion is effected by penetration hyphae, causing no extensive dissolution of the cork wall. Electron microscopical observations revealed fine structural details of the fruit bodies and of the intracellular hyphae. Of special interest were the finger-like hyaline hyphae in the last-formed layer of cork cells, which are interpreted as haustoria on the basis of the fine structure both of hyphae and host cells. This situation is considered as reflecting a parasitic relationship of Ascodichaena to beech bark. The activity of the fungus led also to the increased production of cork cells, perhaps related to the nutrient supply of the fungus.     

Light screening in lichen cortices can be quantified by chlorophyll fluorescence techniques for both reflecting and absorbing pigments

Lichens, representing mutualistic symbioses between photobionts and mycobionts, often accumulate high concentrations of secondary compounds synthesized by the fungal partner. Light screening is one function for cortical compounds being deposited as crystals outside fungal hyphae. These compounds can non-destructively be extracted by 100% acetone from air-dry living thalli. Extraction of atranorin from Physcia aipolia changed the lichen colour from pale grey to green in the hydrated state, whereas acetone-rinsed and control thalli were all pale grey when dry. Removal of parietin from Xanthoria parietina changed the colour of desiccated thalli from orange to grey. Colour changes were quantified by reflectance measurements. By a new chlorophyll fluorescence method, screening was assessed as the decrease in incident irradiance (PAR) necessary to reach identical effective quantum yields of PSII (Φ_PSII) in acetone-rinsed and control thalli. Thereby, we estimated a screening efficiency due to cortical atranorin crystals at 61, 38, and 40% of blue, green and red light, respectively, whereas parietin screened 81, 27 and 1% of these wavelength ranges. Removal of atranorin caused similar levels of increased photoinhibition for P. aipolia in blue, green and red light, whereas parietin-deficient thalli of X. parietina exhibited increased photoinhibition with decreasing wavelengths. Atranorin possibly prevents water from entering the spaces between the hyphae in the cortex. The air-filled cavities with white atranorin crystals reflect excess light, whereas the yellow compound parietin absorbs excess light. Thereby, both atranorin and parietin play significant photoprotective roles for symbiotic green algae, but with compound-specific screening mechanisms.     

Die Verschiedenartigkeit von Haftorganen einiger Flechten

Summary The rhizines of the lichens, Parmelia caperata, Parmelia trichotera and Lobaria pulmonaria were studied with the Stereoscan scanning electronmicroscope and in ultrathin sections with the transmission electronmicroscope. The rhizines are composed of fungal hyphae.The fungal hyphae in the rhizines of the thallus of Parmelia caperata and in the cilia at the thallus border of Parmelia trichotera are connected by a glue-like substance. The ends of the Parmelia caperata rhizines are flattened and enlarged. With these footlike rhizines the thalli are in good connection with the substratum. The cilia at the thallus border of Parmelia trichotera have a tip by which the thallus is fixed on bark or rocks. The cell walls of the fungi hyphae in the Parmelia caperata rhizines and in the Parmelia trichotera cilia are 150–400 nm thick.The rhizines of Lobaria pulmonaria consist of fungi hyphae which are interlaced without a gluey substance. The thallus of Lobaria pulmonaria is connected to the substratum through the tips of single hyphae. The hyphae walls of Lobaria pulmonaria are 800–1800 nm thick.     

Scytinostroma galactinum as a pathogen of woody plants

Scytinostroma galactinum (Fr.)Donk is the fungus commonly known asCorticium galctinum (Fr.)Burt. Although it occurs as a saprobe on woody plants and plant debris, it also has been considered by several authors as an active pathogen that causes a white root and butt or collar rot. During the summer of 1970, it was found near Baltimore and also in Montgomery County, Maryland, under circumstances that seemingly provide additional records of pathogenicity. Several other Maryland records are cited, and many Canadian studies have been reviewed.S. galactinum has a distinctive dextrinoid mycelium, which is characteristic enough to permit a tentative identification even in the absence of other features. Outstanding elements of the basidiocarp are the dextrinoid hyphae and slender gloeocystidia. In culture, dextrinoid fiber hyphae and papillate oil-bearing hyphae with clamp connections are characteristic. These and other features of the basidiocarp and culture serve in the characterization of this fungus, which is economically significant and widely distributed.     

Medicago truncatula Vapyrin is a novel protein required for arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizal (AM) symbiosis is a widespread mutualism formed between vascular plants and fungi of the Glomeromycota. In this endosymbiosis, fungal hyphae enter the roots, growing through epidermal cells to the cortex where they establish differentiated hyphae called arbuscules in the cortical cells. Reprogramming of the plant epidermal and cortical cells occurs to enable intracellular growth of the fungal symbiont; however, the plant genes underlying this process are largely unknown. Here, through the use of RNAi, we demonstrate that the expression of a Medicago truncatula gene named Vapyrin is essential for arbuscule formation, and also for efficient epidermal penetration by AM fungi. Vapyrin is induced transiently in the epidermis coincident with hyphal penetration, and then in the cortex during arbuscule formation. The Vapyrin protein is cytoplasmic, and in cells containing AM fungal hyphae, the protein accumulates in small puncta that move through the cytoplasm. Vapyrin is a novel protein composed of two domains that mediate protein–protein interactions: an N‐terminal VAMP‐associated protein (VAP)/major sperm protein (MSP) domain and a C‐terminal ankyrin‐repeat domain. Putative Vapyrin orthologs exist widely in the plant kingdom, but not in Arabidopsis, or in non‐plant species. The data suggest a role for Vapyrin in cellular remodeling to support the intracellular development of fungal hyphae during AM symbiosis.     

CATENOPHLYCTIS,A NEW GENUS OF THE CATENARIACEAE

Catenophlyctis gen. nov. is established in the family Catenariaceae to include the fungus previously known as Phlyctorhiza variabilis Karling. This ubiquitous saprophyte was formerly included in the genus Phlyctorhiza Hanson of the Chytridiales on the grounds that its eucarpic thallus is predominantly monocentric and because it develops usually from an enlargement of the germ tube. Additional studies on this species in India have confirmed the previous observations that the thallus of some strains frequently becomes extensively polycentric and Catenaria-like. Also, its zoospores have been found to be similar in structure to those of species of the Catenariaceae. Accordingly, this species cannot be retained in Phlyctorhiza as Hanson defined the genus, and it is transferred from the Chytridiales to a new genus of the family Catenariaceae in the order Blastocladiales.