Tetrachaetum Elegans Research Articles

Diversity of water-borne conidial fungi in some freshwater bodies of Kumaun Himalaya in district Nainital (Uttarakhand), India

The aquatic ecosystem harbours a variety of micro-organisms, among which water-borne conidial fungi occupy an important place. Their occurrence in freshwater habitat has great significance in the decomposition of submerged plant materials, nutrient release and productivity. Their occurrence and frequency to extreme temperatures and pH may have a profound effect on fungal community composition and metabolic activities. The present paper deals with the diversity of conidial aquatic fungi from different unexplored freshwater bodies flowing through different elevations (1000-1500 m) in district Nainital, Kumaun Himalaya. Comparative study of species composition in different seasons, sporulation temperatures and pH conditions was also carried out. In all, 18 species of conidial fungi belonging to 14 genera were recorded, out of which maximum species (11 species) were recorded in both rainy (July to September) and winter seasons (November to December). Anguillospora crassa, Beltrania rhombica, Campylospora chaetocladia, Cylindrocarpon aquaticum, Helicomyces roseus and Tetracladium setigerum were isolated only during rainy season; Alatospora acuminata, Clavariopsis aquatica, Clavatospora tentacula, Lemonniera pseudofloscula, L. terrestris and Tetrachaetum elegans were isolated only during winter season while Lunulospora curvula, L. cymbiformis, Setosynnema isthmosporum, Tetracladium marchalianum and Triscelophorus acuminatus were isolated in both rainy and winter seasons. The preferred pH and the sporulation temperature ranged from 6-7 and 15-20 °? respectively. The results of the present study are clearly indicating fungal species composition variations along pH, temperature, seasonal and altitudinal gradients and the sites selected for this exploratory investigation are being undertaken for the first time.

New root endophytic water borne conidial fungi from Kumaun Himalaya

<p>Water borne conidial fungi occurring in living roots of healthy plant growing in the wet and ravine areas of Dogaon and Ramgarh, Nainital, Kumaun Himalaya (India) were isolated as root endophytes. A total of 15 species (<em>Alatospora acuminata, Anguillospora longissima, Beltrania rhombica</em>,<em> Campylospora chaetocladia, Claviriopsis aquatica, Cylindrocarpon aquaticum, Flagellospora penicilloides, Helicomyces roseus, Helicosporium lumbricoides, Pleurophragmium sonum, Pestalotiopsis submersus, Seridium sp, Setosynnema isthomosporum, Tetrachaetum elegans </em>and<em> Tetracladium marchalianum</em>) of endophytic aquatic fungus were recovered as root endophytes of various host plants.<em> </em>Three species viz.<em> Helicosporium lumbricoides, Pleurophragmium sonum </em>and <em>Setosynnema isthomosporum </em>isolated from the roots of pteridophytes and grasses were found as new root endophytes. Among the studied host plants five plant species were also found as new hosts.</p>

Ethanol and phenanthrene increase the biomass of fungal assemblages and decrease plant litter decomposition in streams

Fungi, particularly aquatic hyphomycetes, have been recognized as playing a dominant role in microbial decomposition of plant litter in streams. In this study, we used a microcosm experiment with different levels of fungal diversity (species number and identity) using monocultures and combinations with up to five aquatic hyphomycete species (Articulospora tetracladia, Tricladium splendens, Heliscus submersus, Tetrachaetum elegans and Flagellospora curta) to assess the effects of ethanol and phenanthrene on three functional measures: plant litter decomposition, fungal biomass accrual and reproduction. Alder leaves were conditioned by fungi for 7days and then were exposed to phenanthrene (1mgL−1) dissolved in ethanol (0.1% final concentration) or ethanol (at the concentration used to solubilise phenanthrene) for further 24days. Exposure to ethanol alone or in combination with phenanthrene decreased leaf decomposition and fungal reproduction, but increased fungal biomass produced. All aspects of fungal activity varied with species number. Fungal activity in polycultures was generally higher than that expected from the sum of the weighted performances of participating species in monoculture, suggesting complementarity between species. However, the activity of fungi in polycultures did not exceed the activity of the most productive species either in the absence or presence of ethanol alone or with phenanthrene.

Growth responses of aquatic hyphomycetes to different sources of carbon and nitrogen

Assessment of different sources of carbon and nitrogen in terms of dry weight biomass of four selected aquatic hyphomycetes viz; Flagellospora penicilloides Ingold, Pestalotiopsis submersus Sati and Tiwari, Tetrachaetum elegans Ingold and Tetracladium marchalianum De Wildeman was made for their nutritional requirements. Eight carbon sources and ten nitrogen sources were singly added to the basal media in order to provide 4g of carbon and 1g of nitrogen per litre of distilled water. Among carbon compounds glucose and sucrose were found to be most suitable sources of carbon for all the four fungal isolates, where as fructose proved good for T. marchalianum, P. submersus and F.penicilloides fairly. Cellulose was found a poor source of carbon for the growth of all these isolates. The inorganic sources of nitrogen were found as good nitrogen sources with preference for ammonium ions. Suitability of amino acids was found variable from species to species for nitrogen. T.elegans and T.marchalianum had their maximum growth in asparagines, whereas, P. submersus had their highest growth in proline. Cysteine was observed as a good source of nitrogen for almost all the fungal isolates used. Anova calculated for these observed data showed significant variations in the dry weight production of different fungal species grown in different sources of carbon and nitrogen(P<0.01).

Preliminary Insights into the Phylogeography of Six Aquatic Hyphomycete Species

Aquatic hyphomycetes occur worldwide on a wide range of plant substrates decomposing in freshwaters, and are known to play a key role in organic matter turnover. The presumed worldwide distribution of many aquatic hyphomycete species has been based on morphology-based taxonomy and identification, which may overlook cryptic species, and mask global-scale biogeographical patterns. This might be circumvented by using DNA sequence data. The internal transcribed spacer (ITS) region from rDNA was recently designated as the most suitable barcode for fungal identification. In this study, we generated ITS barcodes of 130 isolates belonging to 6 aquatic hyphomycete species (Anguillospora filiformis, Flagellospora penicillioides, Geniculospora grandis, Lunulospora curvula, Tetrachaetum elegans and Tricladium chaetocladium), and collected from streams of Southwest Europe (86 isolates) and East Australia (44 isolates). European and Australian populations of 4 species (A. filiformis, F. penicillioides, G. grandis and T. elegans) grouped into different clades, and molecular diversity indices supported significant differentiation. Continents did not share haplotypes, except for T. chaetocladium. Overall results show substantial population diversity for all tested species and suggests that the biogeography of aquatic hyphomycetes may be species-specific.

Interactions between aquatic bacteria and an aquatic hyphomycete on decomposing maple leaves

Abstract Processing of leaf litter is an important function in many environments and is influenced strongly by microorganisms. We investigated interactions between an aquatic hyphomycete, Tetrachaetum elegans , and two bacteria from the Cytophaga-Flavobacterium-Bacteroides group, that were isolated from decaying leaves in a stream. Laboratory experiments were used to examine interactions, as indicated by growth, between bacteria and fungi on sugar maple ( Acer saccharum ) leaves. Responses to amendments with labile dissolved organic carbon (DOC) were also examined. Fungal biomass was not affected by glucose amendment or bacterial presence. Likewise, bacterial biomass did not respond consistently to the glucose amendment, nor did the fungus affect bacterial biomass. In general, we found little evidence of resource competition or facilitation, in contrast to other studies. Our experiments suggest that fungal–bacterial interactions are not always significant and may depend on environmental conditions and the types of microorganisms examined.

Effects of Cadmium and Phenanthrene Mixtures on Aquatic Fungi and Microbially Mediated Leaf Litter Decomposition

Urbanization and industrial activities have contributed to widespread contamination by metals and polycyclic aromatic hydrocarbons, but the combined effects of these toxics on aquatic biota and processes are poorly understood. We examined the effects of cadmium (Cd) and phenanthrene on the activity and diversity of fungi associated with decomposing leaf litter in streams. Leaves of Alnus glutinosa were immersed for 10days in an unpolluted low-order stream in northwest Portugal to allow microbial colonization. Leaves were then exposed in microcosms for 14days to Cd (0.06-4.5mgL(-1)) and phenanthrene (0.2mgL(-1)) either alone or in mixture. A total of 19 aquatic hyphomycete species were found sporulating on leaves during the whole study. The dominant species was Articulospora tetracladia, followed by Alatospora pulchella, Clavatospora longibrachiata, and Tetrachaetum elegans. Exposure to Cd and phenanthrene decreased the contribution of A. tetracladia to the total conidial production, whereas it increased that of A. pulchella. Fungal diversity, assessed as denaturing gradient gel electrophoresis fingerprinting or conidial morphology, was decreased by the exposure to Cd and/or phenanthrene. Moreover, increased Cd concentrations decreased leaf decomposition and fungal reproduction but did not inhibit fungal biomass production. Exposure to phenanthrene potentiated the negative effects of Cd on fungal diversity and activity, suggesting that the co-occurrence of these stressors may pose additional risk to aquatic biodiversity and stream ecosystem functioning.

Assessment of root endophytic aquatic hyphomycetous fungi on plant growth

The role of root endophytic aquatic hyphomycetous fungi in plant health was studied by employing pot experiments. Three aquatic hyphomycetous fungi Heliscus lugdunensis, Tetrachaetum elegans and Tetracladium nainitalense isolated as root endophytes of riparian plants were artificially inoculated into two test plants viz., Solanum melongena and Hibiscus esculentus. T. elegans and H. lugdunensis showed significant effects (fresh weight, dry weight and length of shoots and roots) on both test plants, whereas T. nainitalense had no effect.

Antagonism of Some Aquatic Hyphomycetes against Plant Pathogenic Fungi

The antagonistic activity of five aquatic hyphomycetes, viz., Heliscus lugdunensis, Tetrachaetum elegans, Tetracladium breve, T. marchalianum, and T. nainitalense, against seven plant pathogenic fungi was studied using a dual culture technique. Inhibitory activity of tested aquatic hyphomycetes was determined by measuring the radial growth of plant pathogenic fungi on dual culture plates. Tetrachaetum elegans showed antagonistic activity against Colletotrichum falcatum, Fusarium oxysporum, Pyricularia oryzae, Sclerotium sclerotiorum, and Tilletia indicaHeliscus lugdunensis showed antagonism against only two plant pathogenic fungi, Rhizoctonia solani and Colletotrichum falcatum.Tetracladium breve, T. marchalianum, and T. nainitalense showed no response towards tested plant pathogenic fungi.

Aquatic Hyphomycetes in the Parque Estadual das Fontes do Ipiranga - PEFI, São Paulo, Brazil

In the State Park Parque Estadual das Fontes do Ipiranga - PEFI, located in the city of Sao Paulo, samples of submerged mixed leaf litter were collected monthly from 10 sites with different levels of eutrophication, from October 2003 to April 2005. Some abiotic factors, such as pH, temperature, conductivity and dissolved oxygen were simultaneously measured in 20 cm deep water at each site. The leaf litter samples were washed in laboratory, cut into 1 cm2 pieces and incubated in Petri dishes containing distilled sterile water for five to seven days at 15 °C to 20 °C. Twenty-four aquatic Hyphomycete species were identified, with predominance of Anguillospora crassa Ingold, Lunulospora curvula Ingold, Tetrachaetum elegans Ingold and Camposporium pellucidum (Grove) Hughes. First reports for South America are: Anguillospora filiformis Greathead, Dendrospora erecta Ingold and Pyramidospora casuarinae Nilsson. These species, as well as Tetracladium setigerum (Grove) Ingold, Tricladium splendens Ingold and Varicosporium elodeae Kegel, are reported for the first time in Brazil. According to the multivariate analysis, the occurrence of the aquatic Hyphomycetes was mainly influenced by the trophic level of the aquatic environments.

Effects of aquatic fungi on feeding preferences and bioenergetics of Pycnopsyche gentilis (Trichoptera: Limnephilidae)

Previous studies which have tested the feeding preferences of shredders for fungal species and the food quality of fungi used detritus uniformly colonized by a fungus, which is not the case for decaying leaves in streams. It is not known whether shredders in different development stages exhibit variations in feeding preference and larval performance. This study examined the feeding preferences and the growth of the third and the fifth instars of Pycnopsyche gentilis larvae using fungal-colonized patches and whole leaves, respectively, having different fungal species compositions (Alatospora acuminata, Anguillospora filiformis, Articulospora tetracladia, Tetrachaetum elegans, and all species combined). The aquatic hyphomycetes used were co-dominant on leaves in the stream inhabited by the caddisfly. During 14 d of feeding, the larvae of both instars did not show significant differences in feeding preferences for the patches growing on oak leaves, although the third instar larvae were slightly more selective than the fifth instar larvae. When fed with maple leaves for 18 d, larval growth rates, gross growth efficiencies, and survivorship were not significantly different among the fungal treatments. However, the larval growth of both instars fed with fungal-colonized leaves was always significantly greater than the growth of larvae fed with diets of uncolonized leaves. The third instar larvae grew faster than the fifth instar larvae, but the growth efficiencies of the two instars were similar. These results suggest that P. gentilis larvae exhibit less selectivity in their feeding than other caddisfly shredders that have been examined and that the dominant fungi colonizing leaves in their habitat are similar in palatability and food quality for this shredder.

Out of the rivers: are some aquatic hyphomycetes plant endophytes?

Ingoldian fungi, or aquatic hyphomycetes, are asexual microfungi, mostly ascomycetes, commonly occurring in running freshwater. They grow on dead plant material, such as leaves and twigs, and play a major role in nutrient flows in stream ecosystems (Barlocher, 1992). They were discovered and first extensively studied by Ingold (1942) and were thus named "Ingoldian" fungi. Ingold described their abundant multicellular asexual spores of sigmoid or, more typically, tetraradiate shape (Fig. 1). He recognized that they probably arose from multiple convergent evolutions, by secondary adaptation to aquatic life, as recently confirmed by molecular markers (Belliveau & Barlocher, 2005; Baschien et al., 2006). Because of their apparent lack of sexuality, Ingoldian species were placed in asexual genera, such as Tricladium or Tetracladium, based on conidial morphology and/or mode of conidiogenesis. Unexpectedly, several lines of evidence now suggest that some Ingoldian fungi are also plant endophytes, that is, they grow in plants without producing symptoms.[...]

The breakdown of Blue Gum (Eucalyptus globulus Labill.) bark in a Portuguese stream

Eucalypt forests produce large amounts of bark, which potentially accumulate in streams, constituting an important carbon and nutrient source for benthic food webs. In this study, we compared the breakdown (and associated microbial activity and diversity and invertebrate abundance) of Eucalyptus globulus bark and leaves, enclosed in coarse and fine mesh bags, in a 3 rd order stream of central Portugal. Biofilm development on bark was also analyzed with scanning electronic microscopy and respiration rates quantified. After 90 days of incubation, bark lost 21-51 % of its initial mass while leaves lost 48-57 %. Fungal biomass (as determined from ergosterol concentrations) increased over time and was higher in leaves than in bark (79 vs. 50 mg [g AFDM] -1 at day 90). Sporulation by aquatic hyphomycetes was only observed after 2 weeks (leaves and bark in coarse mesh bags) or 2 months (bark in fine mesh bags). The initial litter mass converted into conidia in leaves was 7-45 fold the values found in bark. Fungal communities were dissimilar in the two substrates with bark presenting the lowest number of species. Lunulospora curvula and Anguillospora crassa dominated the fungal communities in bark, while L. curvula and Tetrachaetum elegans were the dominant species in leaves. Respiration rates, as a measurement of microbial activity, were lower in bark than in leaves (0.10 vs. 0.25 mg O 2 [g AFDM] -1 h -1 in fine mesh and 0.11 vs. 0.39 mg O 2 [g -1 AFDM] -1 h -1 in coarse mesh). Biofilms in bark clearly increased after 15 days of immersion and contributed to 6-85 % of total oxygen consumption. Overall, the results suggest that microbial decomposition pathways dominate the processing of eucalyptus leaves and bark, although leaching and physical fragmentation may stimulate and facilitate the breakdown of bark.

Aquatic hyphomycetes as endophytes of riparian plant roots

Eighteen species of aquatic hyphomycetes were recorded as root endophytes in roots of living plants including grasses and pteridophytes from wet fields near ravine areas. Alatospora acuminata, A. pulchella, Acaulopage tetraceros, Anguillospora crassa, Campylospora chaetocladia, Lemonniera cornuta, L. pseudofloscula, L. terrestris, Pestalotiopsis submersus and Tetrachaetum elegans were found for the first time as root endophytes. A. longissima, Campylospora purvula, Clavariopsis aquatica, Cylindrocarpon aquaticum, Heliscus lugdunensis, Lunulospora curvula, Tetracladium marchalianum and T. setigerum, which were known previously as root endophytes, are reported here on new hosts. Maximum occurrence was found in November and December.

Aquatic hyphomycetes as endophytes of riparian plant roots

Eighteen species of aquatic hyphomycetes were recorded as root endophytes in roots of living plants including grasses and pteridophytes from wet fields near ravine areas. Alatospora acuminata, A. pulchella, Acaulopage tetraceros, Anguillospora crassa, Campylospora chaetocladia, Lemonniera cornuta, L. pseudofloscula, L. terrestris, Pestalotiopsis submersus and Tetrachaetum elegans were found for the first time as root endophytes. A. longissima, Campylospora purvula, Clavariopsis aquatica, Cylindrocarpon aquaticum, Heliscus lugdunensis, Lunulospora curvula, Tetracladium marchalianum and T. setigerum, which were known previously as root endophytes, are reported here on new hosts. Maximum occurrence was found in November and December.

Competitive Interaction between Two Aquatic Hyphomycete Species and Increase in Leaf Litter Breakdown

Aquatic hyphomycete species produce large numbers of conidia which rapidly colonize the leaf litter that falls into rivers during autumn. Our objective was to understand how a species which produces many fewer conidia than another in laboratory conditions can nevertheless be codominant in a natural setting. In microcosm studies with two pioneer dominant species, Flagellospora curvula and Tetrachaetum elegans, inoculated on alder leaves, we first verified that the ratio of the conidium production of both species (6 to 7:1) was inverse to that of individual conidial masses (1:7) as previously described. Calculating the percentage of leaf mass loss that corresponds to 1A mg of conidial mass produced, the combination of the two species produced 2.9-fold more loss than the mean of each species. By contrast, the reproductive biomasses of F. curvula and T. elegans were 5.2- and 2.6-fold lower, respectively. As a result, the conidium production of F. curvula in the combination was only 3.2-fold that of T. elegans instead of 6- to 7-fold in pure culture. In a mixed culture of the two species, T. elegans conidia had a high germination potential (>90%) whereas the proportion of germinated F. curvula conidia was only 50%. Moreover, T. elegans reduced the area on which F. curvula could grow on poor and rich solid media. These results indicate that the dominance of F. curvula conidia in the river may be partly controlled by T. elegans and suggest that a negative interaction between microfungi may have a positive effect on the ecosystem functioning.

Infraspecific genetic diversity and substrate preference in the aquatic hyphomycete Tetrachaetum elegans

Spores of Tetrachaetum elegans were isolated in early autumn from submerged leaves which were randomly collected at a single site from a small stream in southwestern France. In order to investigate potential substrate preferences, spores were sampled in four leaves from seven different plant genera. A total of 96 monosporic isolates were screened for genetic variation in RAPD patterns using nine different primers. Fifty-two fragments were identified and used for calculation of similarity coefficients. A large number of fragments were shared across all isolates, suggesting that the population was genetically homogeneous. The combination of 11 polymorphic fragments contributed to the delineation of 13 RAPD types. Colonization of a single leaf by multiple genotypes was frequently encountered. Fungal genetic assemblages differed between plant genera. Variations in the frequency of occurrence of the various genotypes are discussed in terms of ecological strategies and in reference to previous work at the community level. We suggested two hypotheses: first, substrate preferences are found among aquatic hyphomycete genotypes, and secondly, sequential occupation by distinctive populations may result in different assortments of genotypes on leaf litters of different plants at any given time of sampling.

Aquatic hyphomycetes in three rivers of southwestern France. II. Spatial and temporal differences between species

Spatial and temporal changes in conidial concentration of species of aquatic hyphomycetes were studied in three southwestern French rivers (Adour, Nive, and Tech). The survey was conducted from source to mouth for a year by water filtration. Fifty-two species were identified. Alatospora acuminata and Clavariopsis aquatica were the most abundant species in all three rivers. Most other species made small contributions to the total amount of conidia, but species such as Heliscella stellata or Lemonniera aquatica occasionally may be important in a particular river. The timing of seasonal peaks of conidia concentration of some species was studied. Species were classified into three groups according to the similarity or differences among rivers. Peak conidial concentration could appear at the same season on the three rivers (e.g., Alatospora acuminata, Articulospora tetracladia, Heliscella stellata, Lemonniera aquatica, Lunulospora curvula) or in different seasons on the three rivers (e.g., Pyricularia submersa, Tetrachaetum elegans). No peak was found for Clavariopsis aquatica or Clavatospora longibrachiata on any river. Changes in conidial concentration along the three rivers were analysed. Patterns of individual species varied among rivers and seasons. During summer on the Tech River, conidial concentration of Heliscella stellata increased abruptly to the highest values of this study after having remained close to zero in the uppermost 20 km. This coincided with a drastic decrease in community diversity in these reaches. Both altitude and downstream distance influence conidial concentrations in a complex manner. Key words: Ingoldian fungi, conidia concentration, season, elevation.

Changes in concentration of aquatic hyphomycete conidia in water passing through a concrete pipe

Changes in conidial numbers of aquatic hyphomycetes in water passing through a concrete pipe were investigated by water filtration. Retention in the pipe was low and concentrations of conidia of Alatospora acuminata, Anguillospora longissima, Clavariopsis aquatica, Clavatospora longibrachiata, Heliscella stellata, Lemonniera terrestris, Lunulospora curvula, Pyricularia submersa, Tetrachaetum elegans and Tetracladium marchalianum were unchanged after 1.8 km drift. Only one species, Articulospora tetracladia , showed significant decrease, resulting in part from fragmentation of the conidia. These results suggest that studies of communities of aquatic hyphomycetes in natural environments by sampling conidia by water filtration need to account for differences in stream retention as well as species specific differences in conidial fragmentation.

Effects of a Coal Mine Effluent on Aquatic Hyphomycetes. II. Laboratory Toxicity Experiments

The effects of iron and manganese on the growth and reproduction of three aquatic hyphomycetes, Alatospora acuminata, Tetrachaetum elegans and Articulospora tetracladia, were assessed in the laboratory. Previous studies had indicated that T. elegans and A. acuminata appeared not to colonize leaf material below a discharge from an abandoned coal mine, whereas the distribution of A. tetracladia was not affected by this effluent. The principal contaminants of this effluent were iron and manganese. Neither iron nor manganese had inhibitory effects on the growth of the three species investigated. Indeed, mycelial extension rates of A. tetracladia were stimulated by the presence of iron. Reproduction was however, affected, with the sporulation of both T. elegans and A. acuminata being significantly reduced by exposure to either iron or manganese. By contrast, no significant effect on sporulation of A. tetracladia was observed. There was no significant effect of either metal on conidial germination of the three species. The apparent field distribution of fungi was related to their sensitivities to metals in the laboratory. Those species which appeared to be excluded by the discharge produced few or no conidia when exposed to metals at concentrations equivalent to those recorded at the contaminated site. Since conidia were used to detect aquatic hyphomycetes, it is unclear whether A. acuminata and T. elegans were indeed absent below the discharge or were present as mycelium which, being unable to sporulate, cannot be identified.