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Lignin peroxidase and laccase gene-specific PCR primers were used to screen 38 diverse basidiomycetes and xylariaceous fungi. Lignin peroxidase gene-specific sequences were obtained for basidiomycetes only and were highly divergent. Possession of laccase genes was relatively widespread among basidiomycetes, and is shown for the first time in Xylariaceae. All sequences were highly conserved with no variation resulting in changes to predicted amino acid sequence. Those basidiomycetes shown to possess lignin peroxidase and laccase genes also produced the enzyme in vitro. Conversely none of the xylariaceous fungi shown to possess laccase genes were able to do so, whilst others decolorized Poly R yet yielded no PCR amplicons.
The Amphisphaeriaceae is an important family of ascomycetes within the Xylariales. There has been, however, disagreement regarding the taxonomic placement of many genera within this family and whether it should be confined to ascomycetes producing Pestalotiopsis-like anamorphs. In this study, phylogenetic relationships among members of the Amphisphaeriaceae are investigated using partial sequences of the 28S rDNA. Molecular data provided further evidence to support the association of several coelomycetous genera with the ascomycetous Amphisphaeriaceae. Phylogenetic analyses also show that all ascomycetous genera possessing Pestalotiopsis-like anamorphs are monophyletic and confirm the anamorphic-teleomorphic connections of some. There is, however, insufficient evidence to support the restriction of Amphisphaeriaceae to genera, which produce Pestalotiopsis-like anamorphs, because the phylogenetic placement of Amphisphaeria umbrina is not fully resolved and its affinities with other members received low bootstrap support. The results also indicate that Iodosphaeria and Arecophila should be excluded from the Amphisphaeriaceae. The placement of Lanceispora in the Amphisphaeriaceae is doubtful. A broad concept of the family Amphisphaeriaceae is advocated until further data are available.
Ascospore appendages of two species of Linocarpon and three species of Neolinocarpon are illustrated using electron microscopy. The structure of these appendages can be used to distinguish between species. The ascospore appendages of species in both genera, however, were found to have similar structure. Thus, species of Linocarpon and Neolinocarpon could not be delineated at the generic level based on ascospore appendage structure.
Fungal species richness and abundance were assessed in leaf litter of the Australian rainforest tree Neolitsea dealbata (Lauraceae) using particle filtration. Results were comparable to the species richness and abundance reported in previous studies of tropical leaf litter microfungi. Eight leaf samples yielded 1365 strains. In an assessment of the effect of surface treatments, 736 strains in 112 morphotaxa were isolated, while 639 strains in 141 morphotaxa were recovered to assess the effect of surface treatment. Isolation rates in airdried leaves stored at room temperature for four weeks declined linearly, while the number of morphotaxa remained essentially constant for the first three weeks. Isolates of common morphotaxa were lost preferentially over those of rarer taxa. Such losses of isolates may be acceptable if only presence/absence data are collected. If frequency data are vital for community analysis, only fresh material should be utilised. Two surface sterilisation treatments were applied to N. dealbata leaves. An ethanol/sodium hypochlorite treatment was considered unsuitable because it significantly reduced the number of morphotaxa derived from the leaf lamina. A sodium hypochlorite treatment reduced the number of detectable propagules in the wash water without changing the number of morphotaxa derived from leaf particles in comparison with those of the control group.
Sterile mycelia isolated from Pinus tabulaeformis were grouped into white morphotype strains based on cultural characteristics. Eighteen of the isolates were randomly selected and identified to various taxonomic levels based on nuclear ribosomal DNA (nrDNA) sequence analysis. The 5.8S gene and flanking internal transcribed spacer (ITS1 and ITS2) regions of nrDNA were amplified and sequenced. Phylogenetic analysis of the 5.8S gene sequences indicated that the white morphotype strains were Ascomycota. Further identification was achieved by means of sequence similarity comparison and phylogenetic analysis of the ITS regions. Results showed that strains WMS9 and WMS10 were Lophodermium species (Rhytismataceae), while strains WMS11, WMS13 and WMS18 were species of Rhytismataceae. Strains WMS2, WMS3, WMS4, WMS5 and WMS6 were identified to Rosellinia, strain WMS1 to Entoleuca, and strain WMS14 to Nemania (Xylariaceae). Strains WMS7, WMS8, WMS12, WMS15, WMS16 and WMS17 were xylariaceous species. The potential of using DNA sequence analysis in the identification of endophytic fungi is discussed.
Tropical xylariaceous taxa in the genera Biscognauxia, Hypoxylon and Xylaria were evaluated for their ability to produce wood-decay enzymes and effect mass loss and lignin solubilization in angiosperm and gymnosperm wood. All xylariaceous taxa were capable of cellulose and xylan hydrolysis, but few produced enzymes involved in lignin breakdown. Xylariaceous fungi were incapable of causing mass loss in gymnosperm wood, but several caused significant mass loss in angiosperm wood during a six month in vitro exposure. Mass loss values obtained were low at approx. 20% of those obtained for basidiomycetes. Lignin was solubilized at similar rates to mass loss by Hypoxylon and Xylaria species, resulting in indices of lignin solubilization between 0.88 and 1.11, which were similar to those obtained for white-rot basidiomycetes and higher than those previously reported for any other xylariaceous fungi.
The relationship between teleomorphs of Cordyceps spp. and their presumed anamorphs have been investigated by analysis of 5.8S and ITS rDNA sequences. The morphological and sequence data confirm that Paecilomyceshawkesii is the anamorph of Cordyceps gunnii, while Cordyceps hawkesii is a synonym of C. gunnii, and P. gunnii is a synonym of P. hawkesii. The following presumed connections are also confirmed: Beauveria brongniartii is the anamorph of C. brongniartii, Metarhizium anisopliae var. majus is the anamorph of C. brittlebankisoides, Beauveria sobolifera is the anamorph of C. sobolifera, Mariannaea pruinosa is the anamorph of C. pruinosa, Paecilomyces militaris is the anamorph of C. militaris, and Hirsutellasinensis is the anamorph of C. sinensis. The other isolates sequenced are unlikely to be anamorphs of the teleomorphs from which they were isolated because the sequences from the culture and the teleomorph are quite different. 5.8S and ITS sequences provide useful information for establishing anamorph–teleomorph connections and assisting in the delimitation of species within Cordyceps.
Littoraria ardouiniana and Littoraria melanostoma are common snails in Hong Kong, living and feeding on mangrove trees. Gut content and stable isotopic analyses were conducted to investigate the littorinid's diets. Gut content analyses revealed these snails ingested bark, epidermal plant cells, fungi, and microalgae, but that broken plant cells were the most abundant food items in the stomach and faecal contents. The gut contents of the two littorinid species, either from the mangrove trees Kandelia candel or Aegiceras corniculatum, were similar and showed little temporal variation throughout the year. Dual stable isotopic analysis, which investigated the δ13C and δ15N values of the littorinids and their potential food items, indicated that these littorinids might feed on mixed diets composed of parts of the mangrove trees and other items available on the trees such as phylloplane fungi, microalgae and cyanobacteria. These epiphytic mangrove littorinids are generalist grazers which graze on the substratum non-selectively as they are constrained on their host trees, and their diets are, therefore, dependent on food availability on the trees themselves.
Fungal communities on decaying fronds of Livistona australis, Oraniopsis appendiculata (Australia), Arenga engleri, Livistona chinensis (Hong Kong), Arenga undulatifolia, Salacca affinis, and Oncosperma horridum (Brunei) were examined for fungi. In all, 288 different taxa were identified. The fungal communities on different frond parts (i.e. leaves, rachis-tips, mid-rachides and rachis-bases), on different hosts, at different sampling sites, at different stages of decay, and in different seasons were compared.
Fungal species compositions were distinct on different hosts and at different sites. Three-dimensional correspondence analysis resulted in: (a) three clusters corresponding to distinct communities on samples in Australia, Brunei and Hong Kong; (b) fungi on palms of the same genera (Arenga undulatifolia and A. engleri; Livistona australis and L. chinensis) at different sites, being more coherent than on palms of different genera at different sites; (c) fungi on palms of different genera at the same site being more coherent than on palms of the same genera at different sites. Fungal taxa on the same palm genus or species in different sampling sites were significantly different. Evidence for host specificity and fungal recurrence on different hosts and frond parts were found. No evidence of seasonal patterns of fungal communities was found on the palm hosts. Only 10% of the fungi were common to all three palm species studied in Brunei and 17% were common to the two palm species at Victoria Peak, Hong Kong.
Significant differences were found in the fungal communities colonising each of the different frond parts (leaves, rachis-tips, mid-rachides and rachis-bases). The greatest differences in most palms were found between the leaves and rachides.
When investigating fungal diversity it is recommended to examine a combination of naturally occurring fronds and frond baits throughout the decomposition process. Since a large number of forests, plant species and even types of plant tissues have yet to be explored by mycologists, we predict that there are an incredibly large number of fungi on these unexplored substrata.
This study has confirmed that fungi on palms are very diverse and suggests some reasons for this. The data has important implications towards future biodiversity studies and estimates of global fungal numbers. Future studies and estimations must reflect and incorporate these results.
Estimates of global fungal numbers rely heavily on the ratios of unique fungi to host plants. Evidence for host-specificity, which is basic to our understanding of host to fungus ratios, is therefore explored in this review. There is considerable evidence that some endophytes, pathogens and mycorrhizal fungi are host-specific. Host-specificity however, may be an unwise term for saprobic fungi, and ‘host-exclusivity’ and ‘host-recurrence’ may be more appropriate terms. Concepts of host-specificity, host-exclusivity and host-recurrence are therefore defined and discussed. Suggestions for future work needed in order to establish host-exclusivity and host-recurrence in saprobic fungi are made.
Samples of standing senescent culms of Panicum maximum, Pennisetum purpureum, Phragmites australis, Miscanthus floridulus, Saccharum arundinaceum and Thysanolaena maxima (Gramineae), and Schoenoplectus litoralis (Cyperaceae) were collected in Hong Kong between 1997 to 1999. A total of 205 fungal taxa were identified on these samples, including 61 ascomycetes, and 144 mitosporic taxa. Common fungal genera included Diaporthe, Leptosphaeria, Massarina, Ophiobolus and Ophioceras (ascomycetes), and Monodictys, Phaeoisaria, Periconia, Phoma, Phomopsis, Rhinocladiella, Septoria and Sporidesmium (mitosporic taxa). Different grass species were host to different fungal communities and diversities of taxa. Diversity indices for fungi on the hosts varied from 3·3 to 8·7, the highest index being from Pennisetum purpureum, and were overall higher from species offering more durable, strongly sclerenchymatic substrates. No single saprobic fungus collected in this study is thought to be specific to any one grass, however, certain fungi tended to reoccur on single grass species, but not on adjacent grasses. A ‘core fungal group’ was commonly associated with the decaying grasses and this ‘core’ was thought to be important in nutrient cycling in the grasses. A comparison of the fungi occurring on grasses with those on other monocotyledonous hosts is made. The numbers of fungi known to occur on Juncus roemerianus and Phragmites australis are briefly summarised.
There are approximately 70000 species of described fungi, representing about 5% of the estimated 1·5 M species world-wide. Proportionally there are numerous undescribed species and most habitats and hosts should provide a bounty of novel fungi that can be exploited in a wide variety of ways. Where, however, are these missing fungi? Data indicates that they may occur in poorly studied countries, hosts, habitats, niches or tissues, and are mostly microfungi. Host specificity and/or tissue recurrence are important considerations in biodiversity estimates. We are a long way from establishing where we can find the missing 1·43 M fungi, but evidence presented here resulting from data from Hong Kong indicates many places where we could look.
Fungi on submerged wood in streams are a diverse group, comprising taxa from various families. Fungal communities on submerged wood collected from Sungai Sitam in Brunei, Tai Po Kau Forest Stream in Hong Kong, and from a stream in Lipur Lentang Nature Reserve in Malaysia are reported. One hundred and forty-seven taxa were recorded. A higher species diversity including temperate and tropical species was recorded in Tai Po Kau Forest Stream in the subtropics. Ascomycetes and their asexual stages were dominant in tropical and subtropical freshwater habitats, while discomycetes were rare in these habitats. Distinct fungal communities are found on submerged wood in tropical, subtropical and temperate regions and these are discussed. Including the fungi identified in this study, over 1000 fungi has been recorded from freshwater habitats.
Endophytic fungi were isolated from 7500 samples of wild Musa acuminata collected from five sites at Doi Suthep Pui National Park, Thailand during December 1998 to July 1999. Overall colonization rates from surface sterilized tissues were 56·5, 48·9, 48, 47·9 and 41·7% for the Medicinal Plant Garden, Ban Suthep, Queen Sirikit Botanic Garden, San Gu, and Montatarn waterfall sites respectively. Sixty-one different fungal taxa were isolated. Fewer isolates were recovered from younger than older samples. Xylariaceous taxa and Guignardia cocoicola were the most frequently isolated endophytes from leaves and were either absent or rare in midrib, petiole and pseudostem. Colletotrichum gloeosporioides, C. musae, Guignardia cocoicola, various sterile mycelia and xylariaceous spp. were common at all sites. The endophyte fungal communities at the five sites were found to differ. Deightoniella torulosa was the most frequent isolate at the Ban Suthep site and was either absent or rare at other sites. Colletotrichum species were most common in the midribs and petioles at all sites, while Pyriculariopsis parasitica and Dactylaria sp. were most common in the pseudostems. The endophyte communities isolated from M. acuminata in this study are compared with those from previous studies on tropical hosts. Several of the endophytes isolated are established pathogens of banana and provide support for the hypothesis that some endophytes are latent pathogens. The diversity of fungi on banana is discussed in relation to global estimates of numbers of fungus species.
Brunneosporella aquatica gen. et sp. nov., Aqualignicola hyalina gen. et sp. nov., Jobellisia viridifusca sp. nov. and Porosphaerellopsis
bipolaris sp. nov. are described and illustrated from wood submerged in freshwater collected in Hong Kong. Both Brunneosporella and
Aqualignicola have characteristic features of the Annulatascaceae and their placement within this family is discussed. Jobellisia viridifusca
sp. nov. differs from all described species in having an ascomatal wall with a bright orange middle wall layer and fusiform, greenish-brown
ascospores. Porosphaerellopsis bipolaris sp. nov. is unique in producing multiseptate ascospores with bipolar mucilagilous pads.
Torrentispora fibrosa gen. sp. nov. (Ascomycota, Annulatascaceae) is described based on specimens from submerged wood collected from
streams in Tai Po Kau Forest Reserve, Hong Kong. T. fibrosa is characterized by immersed to superficial ascomata with a peridium of
black cells arranged in irregular rows, wide septate paraphyses, long cylindrical asci with a relatively massive refractive apical ring,
and unicellular ascospores with a fibrillar sheath. Illustrations from light and scanning electron microscopy are provided. It is
compared with species in the genus Annulatascus, from which it differs in ascoma peridium and ascospore sheath morphology, and
with other aquatic ascomycetes possessing ascospores with a similar fibrillar sheath structure.
Endophytic fungi were isolated from three unidentified Licuala sp. palms in Brunei Darussalam and from three L. ramsayi palms in
Australia. Endophytes were very common in both species, with overall colonisation rates of 81–89%. Taking into account a lower
sampling frequency in Australia, endophyte diversity was similar in the two Licuala species. The endophyte assemblages examined
were very diverse, consisting of 75 fertile species and 60 sterile morphospecies. The endophyte communities of both palms were
composed of a single, dominant xylariaceous species, approximately ten less common but equally ubiquitous species and a large
number of species occurring at very low frequencies. Differences were observed between the endophytic mycotas of different palm
tissues and of tissues of different ages. The results presented suggest that most of the endophytes entered the petiole via the leaf
and that transmission of palm endophytes is likely to be horizontal (via airborne propagules) rather than vertical (via seed). Seasonal
differences were not observed in Brunei. Increased sampling effort could be expected to yield more endophyte taxa in both species
Eight new species of Anthostomella, A. acuminata, A. applanata,
A. caffrariae, A. colligata, A. meerensis, A. palmae, A. raphiae and A.
spiralis, are described from South Africa. They are compared with similar species and illustrated with differential interference contrast
A new genus, Halorosellinia, is introduced to accommodate the lignicolous mangrove inhabitant Hypoxylon oceanicum. A detailed
illustrated account of the teleomorphic and anamorphic states is given. Halorosellinia oceanica comb. nov., is compared with
Stilbohypoxylon quisquiliarum and Nemania confluens (a reduced form of Nemania) and the reasons for introducing a new genus are
discussed. Data on the ecology and geographical distribution of H. oceanica are presented.