Relationships between orchid and fungal biodiversity: Mycorrhizal preferences in Mediterranean orchids

Orchidaceae is one of the most species-rich angiosperm families, and all orchids are fully dependent on fungi for their seed germination and their life cycle. The level of specificity of the association between orchid species and fungi can be related to the number of co-occurring orchid species. To investigate orchid mycorrhizal associations in adult-photosynthetic orchids, 16 Mediterranean orchid species belonging to 4 genera (Anacamptis, Ophrys, Orchis, and Serapias) at 11 different sites were subjected to DNA-based analysis. Eighteen operational taxonomic units representing two fungal families, Tulasnellaceae and Ceratobasidiaceae, were identified. All examined orchid species associated with different mycorrhizal fungi. Interestingly, there was a positive correlation between number of orchid species and number of mycorrhizal. Monospecific populations showed a lower number of fungi, while sympatric populations had a higher number of mycorrhizal fungi. Our results showed that Mediterranean orchid species associated with a higher number of mycorrhizal fungi confirming as photosynthetic orchids are typically generalists toward mycorrhizal fungi. Thus, photosynthetic orchids exhibit low specificity for fungal symbionts showing the potential for opportunistic associations with diverse fungi reducing competition for nutrient. We suggest that these characteristics could confer symbiotic assurance particularly in habitat with resource limitations or prone to stressful conditions.     

Monocentric fungi on species of rhizosolenia from saline habitats

Summary Eight monocentric fungi are reported in two provisionally identified species ofRhizosolenia from sea-water. Only two species are assigned specific names. These areRhizophydium planktonicum Canter andR. fragilariae Canter. A fungus with depressed-globose sporangia is included as a form ofR. fragilariae. Two unidentified species ofChytridium are reported. A fungus tentatively assigned toZygorhizidium and a form provisionally assigned toPetersenia are also reported and described insofar as their characteristics are known.     

Some new hosts to Leptosphaerulina McAlp. from India

Summary The present paper describes a species ofLeptosphaerulina occurring on 10 angiospermic hosts belonging to 7 families of dicotyledons. On the basis of perithecial size, shape, septation and size of ascospores, the fungus occurring on all these hosts was considered to be belonging to a single species which was identified asL. australis McAlp. Further work on the taxonomy and nutritional requirements of the fungus is under investigation.     

Newly reported fungi from Orissa (India) — I

Summary Two species of fungi,Tryblidiella rufula (Spreng.)Sacc. andTrabutia butleri Theiss &Syd. have been figured and described for the first time from Orissa. The former was found growing on dead twigs ofCitrus aurantifolia (Christm.)Swingle and onCitrus sp. and the latter on living leaves ofFicus religiosa L.     

Ecological study of soil fungi of an agricultural field in Allahabad

Summary The soil fungi from an agricultural field in Allahabad where sugarcane is being grown for many years, have been isolated from various depths during different seasons and were identified. The inter-relations of chemical composition of soil and distribution of fungi is also being shown here.The techniques for the isolation and the study of the fungus flora was that ofGoddard modified bySaksena &Mehrotra. Soil samples were examined from 1–6 depths in three seasons of the year and were mechanically and chemically analysed.For the isolation, soil dilution plate method, a modification ofMenzies' method, direct method ofWaksman, Rossi Cholodny Burried slide technique, and screened immersion plate method, were followed Fifty five different species of microfungi belonging to Phycomycetes, Ascomycetes and Fungi — Imperfecti were isolated and identified. The moisture contents, hydrogen-ion concentrations, carbon, nitrogen, phosphorus, calcium, magnesium and iron, etc., of the soil samples from 1–6 inches depths, were also studied.Out of these 12 species covering 9 genera belonged to the Phycomycetes, nine genera of Ascomycetes and nine genera of Fungi Imperfecti were recorded.P. multicolor Grigorieva-Monoilova &Poradielova, andP. roqueforti Thom.,Gliocladium vermoesoni (Biourge)Thom. andMasoniella grisea (Smith)Smith were recorded for the first time from Indian Soil. A new varietyChaetominum nigricolor Ames var.simplex was also isolated.     

Hyphomycètes prédateurs de nématodes dans une prairie du Limousin

Résumé Une étude a été réalisée en Limousin sur une prairie permanente paturée par des moutons pour mettre en évidence la présence d'hyphomycètes prédateurs et étudier leur répartition dans le temps. Nous avons isolé 390 souches réparties en 5 genres et 13 espèces. Les champignons sont présents tout le temps; certains ont été isolés d'une manière plus sporadique et d'autres n'ont été trouvés qu'à des moments précis. Nous avons pu démontrer la large répartition géographique d'espèces signalées jusqu'ici de biotopes particuliers. Deux des especes identifiées semblent présenter les qualités requises pour être utilisées en lutte biologique:Dactylaria brochopaga Drechsler et unMonacrosporium sp.

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Summary We have researched the presence of nematophagous fungi during 17 months in a permanent pasture grazed by a flock of sheep. 390 strains were isolated and identified. 13 species from 5 genera were found. One of these species (Arthrobotrys oligospora Fresenius) was present every month, other fungi (8 species) from time to time and 4 species were recovered only once. Some species were evenly distributed on the pasture and could be isolated from all the sites sampled whereas other species were found only in specific sites. Several of the species isolated were reported previously only from very distant geographical regions. Their isolation from France demonstrates their world-wide distribution. The species most commonly encountered were:Arthrobotrys oligospora, A. irregularis Mekhtieva,Dactylaria candida Saccardo andMonacrosporium salinum Cooke & Dickinson. The possible use of 2 speciesD. brochopaga andMonacrosporium sp. in biological control is discussed.

     

Interspecific Interactions among Tropical and Subtropical Freshwater Fungi

Abstract Twenty-seven species of tropical and subtropical fungi isolated from freshwater were examined for evidence of interspecific interactions, which are important in determining the ecological roles of fungi. Evidence for interspecific interactions was examined by inoculating paired fungi 25 mm apart on the surface of agar plates. The antagonistic activities were different among different isolates and even between isolates of the same species, for example, Ophioceras dolichostomum isolated from different origins. Pseudohalonectria longirostrum and Kirschsteiniothelia elaterascus, which produced pigment in culture, were strongly inhibitory species. Several aquatic hyphomycetes seems to be less competitive and less likely to produce antagonistic substances. Competitive abilities were also influenced by the range of enzymes that a fungus produced. For example, Verticillium sp. and Diaporthe sp., which produced only one or two kinds of enzyme, were found to exhibit weak competitive abilities and were easily replaced. The results of competition experiments also showed that slow-extending fungi (e.g., Pseudohalonectria longirostrum and Kirschsteiniothelia elaterascus) were more competitive than early fast-extending fungi (e.g., Ophioceras dolichostomum and Nectria haematococca). Received: 13 October 1998; Accepted: 3 March 1999     

Deep sequencing of mycovirus‐derived small RNAs from Botrytis species

RNA silencing is an ancient regulatory mechanism operating in all eukaryotic cells. In fungi, it was first discovered in Neurospora crassa, although its potential as a defence mechanism against mycoviruses was first reported in Cryphonectria parasitica and, later, in several fungal species. There is little evidence of the antiviral potential of RNA silencing in the phytopathogenic species of the fungal genus Botrytis. Moreover, little is known about the RNA silencing components in these fungi, although the analysis of public genome databases identified two Dicer‐like genes in B. cinerea, as in most of the ascomycetes sequenced to date. In this work, we used deep sequencing to study the virus‐derived small RNA (vsiRNA) populations from different mycoviruses infecting field isolates of Botrytis spp. The mycoviruses under study belong to different genera and species, and have different types of genome [double‐stranded RNA (dsRNA), (+)single‐stranded RNA (ssRNA) and (–)ssRNA]. In general, vsiRNAs derived from mycoviruses are mostly of 21, 20 and 22 nucleotides in length, possess sense or antisense orientation, either in a similar ratio or with a predominance of sense polarity depending on the virus species, have predominantly U at their 5′ end, and are unevenly distributed along the viral genome, showing conspicuous hotspots of vsiRNA accumulation. These characteristics reveal striking similarities with vsiRNAs produced by plant viruses, suggesting similar pathways of viral targeting in plants and fungi. We have shown that the fungal RNA silencing machinery acts against the mycoviruses used in this work in a similar manner independent of their viral or fungal origin.     

Endophytic fungi associated with the Antarctic grass <Emphasis Type="Italic">Deschampsia antarctica</Emphasis> Desv. (<Emphasis Type="Italic">Poaceae</Emphasis>)

Deschampsia antarctica Desv. (Poaceae) represents one of the two vascular plants that have colonized the Antarctic continent, which is usually exposed to extreme environmental conditions. In this work, we have characterized the endophytic fungi associated with the leaves of D. antarctica. Endophytic fungi were recovered from 91 individual plants from different points of Admiralty Bay at King George Island, Antarctica. A total of 26 fungal isolates were obtained from 273 leaf fragments. All isolates were identified by analysis of the sequences of the internal transcribed spacer region (ITS) of the rDNA. Alternaria and Phaeosphaeria were the most frequent genera associated with the plant. Other fungal isolates were identified as Entrophospora sp. and several undescribed Ascomycete species. An interesting result was obtained for the isolates UFMGCB 215 and UFMGCB 262, which were related to fungi associated with bryophytes present in boreal ecosystems. Some isolates showed low identity in the ITS sequences to sequences of fungal species deposited in GenBank, suggesting that these fungi could be new species. This work is the first report on fungal endophytes associated with leaves of the Antarctic grass D. antarctica.     

Normania,an endemic Macaronesian genus distinct fromSolanum (Solanaceae)

Morphological data and results from scanning electron microscopy of seeds and pollen show thatNormania Lowe [syn.Solanum L. subg.Potatoe (G. Don)D'Arcy sect.Normania (Lowe)Bitter] (Solanaceae: Solaneae) should be considered as a distinct genus fromSolanum L. It has two species, one restricted to the island of Madeira [Normania triphylla (Lowe)Lowe] and the other to Tenerife and Gran Canaria [Normania nava (Webb & Berthel.)Franc.-Ort. & R. N. Lester]. These species are extremely rare and had not been found for about 100 years, untilN. nava was rediscovered in two different localities in Tenerife in 1973 and 1982.Normania triphylla was reported in two different places from northern Madeira in 1991. Both species have the highest conservation priority in the Macaronesian region.     

Potentially pathogenic and biocontrol Ascomycota associated with green wall structures of basket willow (<Emphasis Type="Italic">Salix viminalis</Emphasis> L.) revealed by phenotypic characters and ITS phylogeny

Ascomycota are among the fungi that cause serious willow diseases in all natural habitats worldwide. This study was conducted to determine if basket willow used in green wall structures (GWS) built of willow stems were infected by potentially important fungal diseases or their antagonists in urban areas of eastern Canada. In total, 13 different phenotypic genera belonging to eight families of ascomycetous fungi were isolated and identified according to their sexual and/or asexual forms. Venturia pathogenic species complex were represented by three different anamorphs: Fusicladium, Fusicladium-Cladosporium, and Pollaccia as anamorph. They were responsible for the highest incidence value on leaves (IF > 15%). Cryptodiaporthe, Drepanopeziza, and Glomerella dominated on bark (IF > 5%). A significantly higher incidence value of fungal communities was found on first year than on second year GWS. The correspondence analysis using χ² distance showed that communities of potentially pathogenic species are closely related to diseased plants, while healthy plants often contain biocontrol species such as Cladobotryum mycoparasite on healthy bark and Alternaria sp. antagonist on healthy leaves. The phylogenetic positions of the different fungal taxa and their relationship have been revealed by use of PCR amplified internal transcriber spacer (ITS) region of rDNA.     

Re-thinking the classification of corticioid fungi

Corticioid fungi are basidiomycetes with effused basidiomata, a smooth, merulioid or hydnoid hymenophore, and holobasidia. These fungi used to be classified as a single family, Corticiaceae, but molecular phylogenetic analyses have shown that corticioid fungi are distributed among all major clades within Agaricomycetes. There is a relative consensus concerning the higher order classification of basidiomycetes down to order. This paper presents a phylogenetic classification for corticioid fungi at the family level. Fifty putative families were identified from published phylogenies and preliminary analyses of unpublished sequence data. A dataset with 178 terminal taxa was compiled and subjected to phylogenetic analyses using MP and Bayesian inference. From the analyses, 41 strongly supported and three unsupported clades were identified. These clades are treated as families in a Linnean hierarchical classification and each family is briefly described. Three additional families not covered by the phylogenetic analyses are also included in the classification. All accepted corticioid genera are either referred to one of the families or listed as incertae sedis.     

Zoosporic marine fungi from the Pacific Northwest (U.S.A.)

Summary An investigation of the zoosporic fungi in the vicinity of the Friday Harbor Laboratory, San Juan Is., Washington, revealed the presence of great numbers of fungi. With one exception (Olpidium sp.) these were all biflagellate organisms. Predominating were species (11) of Thraustochytriaceae which abounded in water, in association with seaweeds, intertidal sands, and particularly on the surface of bottom samples down to depths of 298 m. A twelfth species of this group has several peculiarities and needs further investigation. Of the algal parasites, one on Polysiphonia and Pterosiphonia is considered new and termed Eurychasma joycei n. sp.The assistance of Drs. R. E. Norris and G. J. Hollenberg in calling my attention to certain algal parasites is gratefully acknowledged. I am also indebted to my colleague Dr. H. C. Whisler, and to Dr. C. Anastasiou for assistance in photographic work.     

Consideration of the taxonomy and biodiversity of Australian ectomycorrhizal fungi

Mycorrhiza management in forestry must be predicated on an understanding of fungal biology and ecology. A fundamental building block of the biology and ecology of any organism is accurate identification and an understanding of its relationship to other organisms. The taxonomy of the larger fungi has been largely based on morphological classification of sexual structures but now Taxonomy routinely incorporates mating studies, and biochemical and molecular data. Taxonomy may not revolutionize theories on mycorrhiza but can clarify some of the inconsistencies due to misrepresentation or over-generalizations and inappropriate conclusions drawn from studies with inaccurately identified fungi. To illustrate this, we discuss and example where incorrect fungal names were repeatedly erroneously applied in morphological and physiological research reports on this fungus, e.g. Laccaria laccata. In this case subsequent taxonomic study revealed the reason for the conflicting research results reported for this fungus. We discuss the status of identifying the ectomycorrhizal fungi in various forest communities in Australia and the relationships of this process to assessing their use in forestry. Recent intensive efforts to collect, isolate and identify Australian ectomycorrhizal fungi have revealed an enormous and unique species diversity, e.g., for truffle-like fungi, over 2000 collections from the last five years alone have yielded 2 new families, 24 new genera, and about 184 new species. Nearly 95% of the described and undescribed fungi from Australia are novel, with some 22 genera and 3 families endemic. In most cases the current systematic knowledge of mycorrhizal fungi is inadequate to support clear framework for Australian taxa. This reflects the traditional Northern Hemisphere view of the world, the uniqueness of the Australian fungal flora, and how poorly it is known. For example, the genus Hymenogaster had been widely acknowledged as the most reduced member of the Cortinariaceae. However recent work on Hymenogaster species from the Southern Hemisphere has offered a number of alternative affinities to various species. We also discuss the role proper identification of the organisms involved plays in understanding the ecosystem. Emphasis should be placed on how species diversity equates with physiological and genetic diversity and how a sound taxonomic understanding of species and their systematic position is essential to properly manage them. Accurate taxonomic information will continue to be required as the basis for assessing the role of ectomycorrhizal fungi in sustained ecological development. Of particular significance is the role of ectomycorrhizal fungi in maintenance of plant diversity in natural ecosystems and those disturbed by management. In conclusion, we present some key research areas involving the use of taxonomy that need priority attention.     

Azaphilones: a class of fungal metabolites with diverse biological activities

This review presents an overview of azaphilones isolated from different species of fungi, detailing their chemical structures and biological activities as covered in the recent literature. Over 170 different azaphilone compounds occur in fungi belonging to 23 genera from 13 families: these azaphilones can be classified into ten different structural groups. Numerous azaphilone structures have been described, particularly from members of the Trichocomaceae and Xylariaceae families. Azaphilones exhibit a wide range of interesting biological activities, such as antimicrobial, antifungal, antiviral, antioxidant, cytotoxic, nematicidal and anti-inflammatory activities. Many of these effects may be explained by the reactions of azaphilones with amino groups, such as those found in amino acids, proteins and nucleic acids, resulting in the formation of vinylogous γ-pyridones.     

Cereal phosphate transporters associated with the mycorrhizal pathway of phosphate uptake into roots

A very large number of plant species are capable of forming symbiotic associations with arbuscular mycorrhizal (AM) fungi. The roots of these plants are potentially capable of absorbing P from the soil solution both directly through root epidermis and root hairs, and via the AM fungal pathway that delivers P to the root cortex. A large number of phosphate (P) transporters have been identified in plants; tissue expression patterns and kinetic information supports the roles of some of these in the direct root uptake pathways. Recent work has identified additional P transporters in several unrelated species that are strongly induced, sometimes specifically, in AM roots. The primary aim of the work described in this paper was to determine how mycorrhizal colonisation by different species of AM fungi influenced the expression of members of the Pht1 gene families in the cereals Hordeum vulgare (barley), Triticum aestivum (wheat) and Zea mays (maize). RT-PCR and in-situ hybridisation, showed that the transporters HORvu;Pht1;8 (AY187023), TRIae;Pht1;myc (AJ830009) and ZEAma;Pht1;6 (AJ830010), had increased expression in roots colonised by the AM fungi Glomus intraradices,Glomus sp. WFVAM23 and Scutellospora calospora. These findings add to the increasing body of evidence indicating that plants that form AM associations with members of the Glomeromycota have evolved phosphate transporters that are either specifically or preferentially involved in scavenging phosphate from the apoplast between intracellular AM structures and root cortical cells. Operation of mycorrhiza-inducible P transporters in the AM P uptake pathway appears, at least partially, to replace uptake via different P transporters located in root epidermis and root hairs. Electronic Supplementary Material Supplementary material is available for this article at     

Biological active metabolite cyclo (l-Trp-l-Phe) produced by South China Sea sponge Holoxea sp. associated fungus Aspergillus versicolor strain TS08

Sponge-associated fungi represent the single most prolific source of novel natural products from marine fungi. Cyclo (l-Trp-l-Phe) exhibits biological functions such as plant growth regulation, moderate cytotoxicity and thus has the application potential in pharmaceutical and agricultural biotechnologies. In this study, a fungal strain TS08 was isolated from sponge Holoxea sp. in the South China Sea and identified as A. versicolor according to its 18S rRNA gene and morphological, physiological, and biochemical characteristics. Meanwhile, cyclo (l-Trp-l-Phe) was found to be produced by A. versicolor strain TS08 mainly in the exponential growth phase. The highest yield of cyclo (l-Trp-l-Phe), 13.24 mg/g (per crude extract of EtOAc), 2.51% of cell dry weigh, was obtained on the tenth day of the fungal cultivation. It was the first time to find the biological active cyclo (l-Trp-l-Phe) in sponge-associated microorganism.     

Studies on hyphomycetes from the Pacific North-west-IV

A new species ofBispora Corda. (i.e.)B. herbicola with 1–3 septate conidia having truncate ends produced on long conidiophores and growing saprophytically on unidentified herbaceous stems, has been described.Chalara cylindrosperma (Corda)Hughes is also reported. These fungi have been collected and described first time from the Pacific North-west.     

Electrophoretically estimated genetic distance and divergence time between chimpanzee and man

Amount of genetic differentiation between chimpanzee and man was estimated from the result of comparative electrophoretic screening of blood protein variations at 32 independent genetic loci. TheNei's genetic distance (D) was calculated as 0.4514, and from this value the divergence time between the two species was estimated as 2.26 million years; considering the variation among amino-acid substitution rate in different proteins, the corrected figures were given as genetic distance of 0.5706 and divergence time of 2.85 million years. This genetic difference is considered too small the two species to be allocated in different families, in accordance with the results of the similar kind of analyses byKing andWilson (1975) and Bruce andAyala (1979). Discussions were made for a discrepancy between the divergence times estimated by using and not by using the splitting time recognized by paleoprimatologists as a reference, and for the difference in the estimations made in different laboratories.