Glyphosate reduces urediniospore development and Puccinia psidii disease severity on Eucalyptus grandis

BACKGROUND

Recent studies have shown the effects of glyphosate drift on decreasing rust intensity on Eucalyptus grandis plants. However, the effects of the herbicide on Puccinia psidii initial development are unknown. In this study the systemic action of glyphosate on rust severity was evaluated on Eucalyptus plants maintained under greenhouse conditions. Urediniospore germination and apressorium formation on detached leaves and on water agar medium, previously treated with glyphosate, were also evaluated.

RESULTS

Rust severity and the number of urediniospores per leaf area were significantly reduced with increasing glyphosate doses, even on branches not directly treated with the herbicide, indicating a systemic effect of glyphosate on pathogen development. Similarly, higher glyphosate doses also reduced germination and apressorium formation on detached Eucalyptus leaves, regardless of the direct application of the product on the leaf limb or on the petiole base. Puccinia psidii urediniospore germination in water agar medium also decreased with increasing herbicide doses.

CONCLUSIONS

Reductions in germination and apressorium formation of P. psidii urediniospores with increasing glyphosate dose indicate that a lower severity and intensity of the disease may perhaps be due to blockage of the shikimic acid pathway in the fungal metabolic system.

Genetic variation and variation in aggressiveness to native and exotic hosts among Brazilian populations of Ceratocystis fimbriata

Ceratocystis fimbriata is a complex of many species that cause wilt and cankers on woody plants and rot of storage roots or corms of many economically important crops worldwide. In Brazil, C. fimbriata infects different cultivated crop plants that are not native to Brazil, including Gmelina arborea, Eucalyptus spp., Mangifera indica (mango), Ficus carica (fig), and Colocasia esculenta (inhame). Phylogenetic analyses and inoculation studies were performed to test the hypothesis that there are host-specialized lineages of C. fimbriata in Brazil. The internal transcribed spacer region ribosomal DNA sequences varied greatly but there was little resolution of lineages based on these sequences. A portion of the MAT1-2 mating type gene showed less variation, and this variation corresponded more closely with host of origin. However, mango isolates were found scattered throughout the tree. Inoculation experiments on the five exotic hosts showed substantial variation in aggressiveness within and among pathogen populations. Native hosts from the same families as the exotic hosts tended to be less susceptible than the cultivated hosts, but there was little correlation between aggressiveness to the cultivated and native hosts of the same family. Cultivation and vegetative propagation of exotic crops may select for strains that are particularly aggressive on those crops.

Decay resistance of thermally-modified Eucalyptus grandis wood at 140 degrees C, 160 degrees C, 180 degrees C, 200 degrees C and 220 degrees C

The objective of this study was to evaluate the effect of thermal treatment on the biological resistance of Eucalyptus grandis wood to the decay fungus Picnoporus sanguineus. Boards from 5 years and 11 months old E. grandis trees, taken from the stock possessed by the Duratex-SA company, were thermally-modified at 140 degrees C, 160 degrees C, 180 degrees C, 200 degrees C and 220 degrees C in the Laboratory of Wood Drying and Preservation from UNESP, Botucatu, SP, Brazil. Samples of each treatment were treated according to ASTM D-2017 (1994). The experiment tested the accelerated decay caused by the decay fungus P. sanguineus on a system of soil-block wood. The results of thermal treatment showed that an increase of temperature of 180-220 degrees C caused reductions of between 15.7% and 82.4% in the weight loss in the samples from E. grandis incubated with P. sanguineus.

Bioethanol production from hydrothermally pretreated Eucalyptus globulus wood

Eucalyptus globulus wood samples were pretreated in aqueous media under non-isothermal conditions to reach maximal temperatures (T(MAX)) in the range 195-250 degrees C, in order to assess the effects of the pre-treatment severity on the fractionation of wood and on the susceptibility of processed samples toward enzymatic hydrolysis. Both the fraction of cellulose susceptible to hydrolysis and the hydrolysis rate increased with the severity of the pre-treatments, but the overall glucose yield decreased for substrates pretreated at T(MAX) above 220 degrees C owing to cellulose losses. Using substrates pretreated at T(MAX)=220 degrees C, up to 94% of polysaccharides were recovered in the hydrolysis media as mono- or oligo-saccharides. High glucose to ethanol conversions were obtained operating at low enzyme charges in Simultaneous Saccharification and Fermentation mode.

Identification of differentially expressed genes of the fungus Hydnangium sp. during the pre-symbiotic phase of the ectomycorrhizal association with Eucalyptus grandis

The pre-symbiotic phase that precedes physical contact between symbionts is a crucial phase in determining their compatibility, allowing the formation of the ectomycorrhiza. A subtractive cDNA library representing the differentially expressed genes of the fungus Hydnangium sp. in the pre-symbiotic phase was constructed using fungal mycelia obtained through the in vitro mycorrhization technique. The fungus was cultured in the presence of Eucalyptus grandis roots, but with no contact between the hyphae and the root system of the host plant. Genes that code for proteins related to carbohydrate, amino acid, and energy metabolisms, transcription, and protein synthesis, cellular communication, signal transduction, stress response, transposons, and proteins related to the biogenesis of cell components were identified among the 131 expressed sequence tags. Expression of the genes that code for acetyl-CoA acetyltransferase, pyruvate dehydrogenase, ATP synthase, a voltage-dependent protein from the selective ion channel, and hydrophobin was evaluated by the RT-qPCR technique, confirming the activation of these genes in this phase of the association.

Nickel-tolerant ectomycorrhizal Pisolithus albus ultramafic ecotype isolated from nickel mines in New Caledonia strongly enhance growth of the host plant Eucalyptus globulus at toxic nickel concentrations

Ectomycorrhizal (ECM) Pisolithus albus (Cooke & Massee), belonging to the ultramafic ecotype isolated in nickel-rich serpentine soils from New Caledonia (a tropical hotspot of biodiversity) and showing in vitro adaptive nickel tolerance, were inoculated to Eucalyptus globulus Labill used as a Myrtaceae plant-host model to study ectomycorrhizal symbiosis. Plants were then exposed to a nickel (Ni) dose-response experiment with increased Ni treatments up to 60 mg kg( - )(1) soil as extractable Ni content in serpentine soils. Results showed that plants inoculated with ultramafic ECM P. albus were able to tolerate high and toxic concentrations of Ni (up to 60 μg g( - )(1)) while uninoculated controls were not. At the highest Ni concentration tested, root growth was more than 20-fold higher and shoot growth more than 30-fold higher in ECM plants compared with control plants. The improved growth in ECM plants was associated with a 2.4-fold reduction in root Ni concentration but a massive 60-fold reduction in transfer of Ni from root to shoots. In vitro, P. albus strains could withstand high Ni concentrations but accumulated very little Ni in its tissue. The lower Ni uptake by mycorrhizal plants could not be explained by increased release of metal-complexing chelates since these were 5- to 12-fold lower in mycorrhizal plants at high Ni concentrations. It is proposed that the fungal sheath covering the plant roots acts as an effective barrier to limit transfer of Ni from soil into the root tissue. The degree of tolerance conferred by the ultramafic P. albus isolates to growth of the host tree species is considerably greater than previously reported for other ECM. The primary mechanisms underlying this improved growth were identified as reduced Ni uptake into the roots and markedly reduced transfer from root to shoot in mycorrhizal plants. The fact that these positive responses were observed at Ni concentrations commonly observed in serpentinic soils suggests that ultramafic ecotypes of P. albus could play an important role in the adaptation of tree species to soils containing high concentrations of heavy metals and aid in strategies for ecological restoration.

Genome sequence of Pantoea ananatis LMG20103, the causative agent of Eucalyptus blight and dieback

Pantoea ananatis is a Gram-negative plant pathogen that causes disease on a broad range of host plants, including pineapple, maize, rice, onion, melons, and Eucalyptus, and has been implicated in several cases of human disease. Here, we report the genome sequence of P. ananatis LMG20103 isolated from diseased Eucalyptus in South Africa.

Effects of tertiary treatment by fungi on organic compounds in a kraft pulp mill effluent

BACKGROUND, AIM AND SCOPE

Pulp and paper mills generate a plethora of pollutants depending upon the type of pulping process. Efforts to mitigate the environmental impact of such effluents have been made by developing more effective biological treatment systems in terms of biochemical oxygen demand, chemical oxygen demand, colour and lignin content. This study is the first that reports an evaluation of the effects of a tertiary treatment by fungi (Pleurotus sajor caju, Trametes versicolor and Phanerochaete chrysosporium and Rhizopus oryzae) on individual organic compounds of a Eucalyptus globulus bleached kraft pulp and paper mill final effluent after secondary treatment (final effluent).

MATERIAL AND METHODS

The tertiary treatment with P. sajor caju, T. versicolor and P. chrysosporium and R. oryzae was performed in batch reactors, which were inoculated with separate fungi species and monitored throughout the incubation period. Samples from effluent after secondary and after tertiary treatment with fungi were analysed for both absorbance and organic compounds. The samples were extracted for organic compounds using solid-phase extraction (SPE) and analysed by gas chromatography-mass spectrometry (GC/MS). The efficiencies of the SPE procedure was evaluated by recovery tests.

RESULTS

A total of 38 compounds (carboxylic acids, fatty alcohols, phenolic compounds and sterols) were identified and quantified in the E. globulus bleached kraft pulp mill final effluent after secondary treatment. Recoveries from the extraction procedure were between 98.2% and 99.9%. The four fungi species showed an adequate capacity to remove organic compounds and colour. Tertiary treatment with R. oryzae was able to remove 99% of organic compounds and to reduce absorbance on 47% (270 nm) and 74% (465 nm). P. sajor caju, T. versicolor and P. chrysosporium were able to remove 97%, 92% and 99% of organic compounds, respectively, and reduce 18% (270 nm) to 77% (465 nm), 39% (270 nm) to 58% (465 nm) and 31% (270 nm) to 10% (465 nm) of absorbance, respectively.

DISCUSSION

The wide variety of organic compounds found in the final effluent must be due to the degradation of E. globulus wood in pulp and paper mill. The concentrations of organic compounds in the final effluent of E. globulus bleached kraft pulp mill were in residual levels maybe due to the secondary treatment. The recovery tests showed the effectiveness of the extraction procedure, and no losses of analyte were suspected in the analytical determinations. Lignin derivatives such as vanilic acid, syringic acid, guaiacol, syringol and phloroglucinol were totally removed by R. oryzae, but the 47% absorbance reduction obtained at 270 nm suggests that these species were not able to complete degradation of lignin macromolecular compounds.

CONCLUSIONS

The organic compounds (carboxylic acids, fatty alcohols, phenolic compounds and sterols) were removed more efficiently by tertiary treatment with R. oryzae or P. chrysosporium, followed by P. sajor caju and T. versicolor. Regarding the removal of both colour and organic compounds, the tertiary treatment with R. oryzae was the most efficient.

RECOMMENDATIONS AND PERSPECTIVES

In order to reduce the deleterious impacts of paper mill effluents, efforts have been made to develop more effective advanced tertiary treatments. This study may serve as a basis of characterisation, in terms of organic compounds of E. globulus bleached kraft pulp mill final effluent after secondary treatment and as an effort to understand the effects of tertiary treatments with fungi on low concentrations of organic compounds from biological secondary treatment.

Contribution of the saprobic fungi Trametes versicolor and Trichoderma harzianum and the arbuscular mycorrhizal fungi Glomus deserticola and G. claroideum to arsenic tolerance of Eucalyptus globulus

The presence of high concentrations of arsenic (As) decreased the shoot and root dry weight, chlorophyll and P and Mg content of Eucalyptus globulus colonized with the arbuscular mycorrhizal (AM) fungi Glomus deserticola or G. claroideum, but these parameters were higher than in non-AM plants. As increased the percentage of AM length colonization and succinate dehydrogenase (SDH) activity in the root of E. globulus. Trichoderma harzianum, but not Trametes versicolor, increased the shoot and root dry weight, chlorophyll content, the percentage of AM root length colonization and SDH activity of E. globulus in presence of all As concentrations applied to soil when was inoculated together with G. claroideum. AM fungi increased shoot As and P concentration of E. globulus to higher level than the non-AM inoculated controls. The contribution of the AM and saprobe fungi to the translocation of As from root to shoot of E. globulus is discussed.

Interactions of Trametes versicolor, Coriolopsis rigida and the arbuscular mycorrhizal fungus Glomus deserticola on the copper tolerance of Eucalyptus globulus

The presence of high levels of Cu in soil decreases the shoot and root dry weights of Eucalyptus globulus. However, higher plant tolerance of Cu has been observed in the presence of the arbuscular mycorrhizal (AM) fungus Glomus deserticola. The hyphal length of G. deserticola was sensitive to low Cu concentrations, and the percentage of AM root colonisation and the metabolic activity of the AM fungus were also decreased by Cu. Therefore, a direct effect of Cu on the development of the AM fungus inside and outside the root cannot be ruled out. E. globulus colonised by G. deserticola had higher metal concentrations in the roots and shoots than do non-mycorrhizal plants; however, the absence of a higher root to shoot metal ratio in the mycorrhizal plants (1.70+/-0.11) indicated that G. deserticola did not play a filtering/sequestering role against Cu. The saprobe fungi Coriolopsis rigida and Trametes versicolor were able to remove Cu ions from the asparagine-glucose growth media. However, plants inoculated with C. rigida and T. versicolor did not accumulate more Cu than non-inoculated controls, and the growth of the plant was not increased in the presence of these fungi. However, C. rigida increased the shoot dry weight, AM root length colonisation, and metabolic mycelial activity of plants colonised with G. deserticola in the presence of Cu; only this saprobe-AM fungus combination increased the tolerance of E. globulus to Cu. Inoculation with G. deserticola and C. rigida increased the E. globulus Cu uptake to levels reached by hyperaccumulative plants.

Growth and mating of Cryptococcus neoformans var. grubii on woody debris

A total of 36 Cryptococcus neoformans strains originating from South Africa were screened for wood degrading enzymes. All strains tested positive for cellulase activity while none where capable of xylan degradation. Three C. neoformans var. grubii strains, originating from clinical and environmental samples, representing the same genotype (VNI/AFLP1-C. neoformans var. grubii) and MATalpha, were evaluated for growth on debris of two common tree species in South Africa: Acacia mearnsii and Eucalyptus camaldulensis. The mating capability of all the C. neoformans strains was evaluated on similar debris. Strains grown on A. mearnsii yielded substantially greater yeast populations. A total of 26%, 6%, 46%, and 80% of the 36 C. neoformans strains tested were either able to mate or develop filaments when crossed on A. mearnsii and E. camaldulensis debris, V8 juice, and yeast carbon base (YCB) agar, respectively. Filamentation and monokaryotic fruiting was observed in 3% of strains when C. neoformans was cultured on either A. mearnsii, E. camaldulensis debris, or YCB. The results indicate that this fungus is capable of completing its life cycle and can produce basidiospores on woody debris. In the future, these findings should be considered when studying the epidemiology, microbial ecology, and proposed infection process of this global pathogen.

Global patterns of ectomycorrhizal introductions

Plants have often been moved across the globe with intact root systems. These roots are likely to have housed symbiotic ectomycorrhizal (EM) fungi and the movement of plants may have facilitated the introduction of EM fungi.Here, we report data compiled from a newly created database of EM fungal introductions.We estimate the magnitude of EM fungal introductions around the world and examine patterns associated with these introductions. We also use the data to develop a framework for understanding the invasion biology of EM fungi.At least 200 species of basidiomycete and ascomycete EM fungi have been moved from native ranges to novel habitats. The majority of recorded introductions are associated with Pinus or Eucalyptus plantations in the southern hemisphere. Most introduced species appear to be constrained from spreading in novel habitats and associate only with their introduced hosts. Aspects of life history, including host range, may influence the ability of EM species to establish or invade. Human-caused introductions of EM fungi are a common and global phenomenon.The mechanisms controlling EM fungi in novel habitats and potential impacts of EM fungal introductions are almost entirely unknown.

Culture-independent assessment of Rhizobiales-related alphaproteobacteria and the diversity of Methylobacterium in the rhizosphere and rhizoplane of transgenic eucalyptus

The rhizosphere is an ecosystem exploited by a variety of organisms involved in plant health and environmental sustainability. Abiotic factors influence microorganism-plant interactions, but the microbial community is also affected by expression of heterologous genes from host plants. In the present work, we assessed the community shifts of Alphaproteobacteria phylogenetically related to the Rhizobiales order (Rhizobiales-like community) in rhizoplane and rhizosphere soils of wild-type and transgenic eucalyptus. A greenhouse experiment was performed and the bacterial communities associated with two wild-type (WT17 and WT18) and four transgenic (TR-9, TR-15, TR-22, and TR-23) eucalyptus plant lines were evaluated. The culture-independent approach consisted of the quantification, by real-time polymerase chain reaction (PCR), of a targeted subset of Alphaproteobacteria and the assessment of its diversity using PCR-denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone libraries. Real-time quantification revealed a lesser density of the targeted community in TR-9 and TR-15 plants and diversity analysis by principal components analysis, based on PCR-DGGE, revealed differences between bacterial communities, not only between transgenic and nontransgenic plants, but also among wild-type plants. The comparison between clone libraries obtained from the transgenic plant TR-15 and wild-type WT17 revealed distinct bacterial communities associated with these plants. In addition, a culturable approach was used to quantify the Methylobacterium spp. in the samples where the identification of isolates, based on 16S rRNA gene sequences, showed similarities to the species Methylobacterium nodulans, Methylobacterium isbiliense, Methylobacterium variable, Methylobacterium fujisawaense, and Methylobacterium radiotolerans. Colonies classified into this genus were not isolated from the rhizosphere but brought in culture from rhizoplane samples, except for one line of the transgenic plants (TR-15). In general, the data suggested that, in most cases, shifts in bacterial communities due to cultivation of transgenic plants are similar to those observed when different wild-type cultivars are compared, although shifts directly correlated to transgenic plant cultivation may be found.

Teratosphaeria nubilosa, a serious leaf disease pathogen of Eucalyptus spp. in native and introduced areas

BACKGROUND

Teratosphaeria nubilosa is a serious leaf pathogen of several Eucalyptus spp. This review considers the taxonomic history, epidemiology, host associations and molecular biology of T. nubilosa.

TAXONOMY

Kingdom Fungi; Phylum Ascomycota; Class Dothideomycetes; Order Capnodiales; Family Teratosphaeriaceae; genus Teratosphaeria; species nubilosa.

IDENTIFICATION

Pseudothecia hypophyllous, less so amphigenous, ascomata black, globose becoming erumpent, asci aparaphysate, fasciculate, bitunicate, obovoid to ellipsoid, straight or incurved, eight-spored, ascospores hyaline, non-guttulate, thin walled, straight to slightly curved, obovoid with obtuse ends, medially one-septate, slightly constricted at the median septum, tapering to both ends, ascospore germination type F, germinating from both ends, germ tubes growing parallel to the long axis of the spore with distortion of the primary ascospore cell.

HOST RANGE

Teratosphaeria nubilosa is a primary pathogen of several Eucalyptus spp., including E. botryoides, E. bicostata, E. bridgesiana, E. cypellocarpa, E. dunnii, E. globulus ssp. bicostata, E. globulus ssp. globulus, E. globulus ssp. maidenii, E. globulus ssp. pseudoglobulus, E. grandis, E. gunnii, E. nitens, E. pilularis, E. quadrangulata, E. viminalis, E. grandis x E. resinifera and E. urophylla x E. globulus.

DISEASE SYMPTOMS

Leaf spots predominantly occur on juvenile Eucalyptus foliage; however, T. nubilosa has also recently been found on mature Eucalyptus foliage. Leaf spots are amphigenous, varying in size from small spots that are round to irregular. Lesions enlarge and coalesce to form larger blotches over the leaf surface. Initial lesions appear as pale-green spots surrounded by purple margins and, once mature, are generally yellow to pale brown with dark-brown raised borders.

USEFUL WEBSITES

Mycobank, http://www.mycobank.org; Mycosphaerella identification website, http://www.cbs.knaw.nl/mycosphaerella/BioloMICS.aspx.

Mycorrhizal morphotyping and molecular characterization of Chondrogaster angustisporus Giachini, Castellano, Trappe & Oliveira, an ectomycorrhizal fungus from Eucalyptus

Chondrogaster angustisporus is a hypogeous ectomycorrhizal fungus described from fruiting bodies collected under Eucalyptus spp. in Brazil, Uruguay, and Australia. Due to its efficiency in promoting plant growth, we decided to characterize this fungus through mycorrhizal morphotyping and internal transcribed spacer (ITS) (rRNA) sequencing. DNA extracted from mycelium was amplified and sequenced using specific primers. Mycorrhizas were obtained aseptically and analyzed in terms of macroscopic and microscopic characteristics. When compared with other fungal DNA sequences available in the NBCI GenBank, the C. angustisporus sequence presented the highest similarity to an uncultured ectomycorrhizal fungus from the Seychelles. It also shows significant similarities to Gomphus, Ramaria, and Hysterangium species supporting the classification of Chondrogaster in the subclass Phallomycetidae in the gomphoid-phalloid group. The mycorrhizas were characterized by a narrow mantle with a single tissue layer densely arranged and organized as a net synenchyma with elongated hyphae. Interhyphal spaces were seen only in the external region where hyphae were more loosely organized. Bottle-shaped cystidia with bent necks were observed on the surface of the mantle. Emanating hyphae were larger than those in the mantle and presented a granular content. At regular intervals the hyphae were divided by septa with clamp connections. The Hartig net was of the common type, with typical palmetti and single hyphal rows and limited to the epidermal layer. The mycorrhizal description and the ITS sequence obtained are useful tools to identify this ectomycorrhizal fungus in culture and in association with Eucalyptus roots.

[Investigation of the presence of Cryptococcus spp. in eucalyptus trees by using sedimentation and swabbing methods]

Yeasts of the genus Cryptococcus are life-threatening microorganisms that cause cryptococcosis in both immunocompromised and immunocompetent humans and animals worldwide. In the nature, Cryptococcus species exist in eucalyptus trees and other species of trees as well as in the soil contaminated with pigeon droppings. The aim of this study was to investigate the presence of Cryptococcus spp. in the samples collected from eucalyptus trees by classic sedimentation and swabbing methods. Regarding these microorganisms, stem hollows, blossom and leaf samples from 61 trees (more than 95% were Eucalyptus camaldulensis) found in and around Adana province (located at Mediterranean region of Turkey) have been examined in June 2006 and June 2007 periods. The samples were then evaluated in terms of the growth of mucoid, dampish and brownish colonies after inoculation onto three media (Guizotia abyssinica birdseed agar with 0.1%, 0.01% and without diphenyl) and incubation in aerobic conditions at 28 degrees C for three weeks. However, no Cryptococcus spp. has been isolated from any of the samples. It was suggested that other species of trees and environmental samples should be examined for the existence of yeast fungi, so that more extensive epidemiological data could be obtained.

Few Mendelian genes underlie the quantitative response of a forest tree, Eucalyptus globulus, to a natural fungal epidemic

Foliar fungal pathogens from the genus Mycosphaerella affect eucalyptus in natural forests and plantations worldwide. QTL analysis was conducted to dissect the genetic control of resistance in Eucalyptus globulus to a natural infection by Mycosphaerella leaf disease, using a clonally replicated outbred F2 family (112 genotypes) planted in a field trial. Two major QTL, with high LOD support (20.2 and 10.9) and high genomewide significance, explained a large proportion (52%) of the phenotypic variance in the severity of damage by Mycosphaerella cryptica, which may be indicative of oligogenic control. Both QTL were validated in a second F2 family and one was validated in a third F2 family. The mean values of different genotype classes at both major QTL argue for Mendelian inheritance with resistance dominant over susceptibility. There were strong correlations between the levels of Mycosphaerella damage in related genetic material planted in three widely separated locations in Tasmania. These findings together provide evidence that the genes controlling resistance to Mycosphaerella damage are stable in different genetic backgrounds and across different environments.

Two independent estimations of stand-level root respiration on clonal Eucalyptus stands in Congo: up scaling of direct measurements on roots versus the trenched-plot technique

Root respiration at the level of a forest stand, an important component of ecosystem carbon balance, has been estimated in the past using various methods, most of them being indirect and relying on soil respiration measurements. On a 3-yr-old Eucalyptus stand in Congo-Brazzaville, a method involving the upscaling of direct measurements made on roots in situ, was compared with an independent approach using soil respiration measurements conducted on control and trenched plots (i.e. without living roots). The first estimation was based on the knowledge of root-diameter distribution and on a relationship between root diameter and specific respiration rates. The direct technique involving the upscaling of direct measurements on roots resulted in an estimation of 1.53 micromol m(-2) s(-1), c. 50% higher than the mean estimation obtained with the indirect technique (1.05 micromol m(-2) s(-1)). Monte-Carlo simulations showed that the results carried high uncertainty, but this uncertainty was no higher for the direct method than for the trenched-plot method. The reduction of the uncertainties on upscaled results requires more extensive knowledge of temperature sensitivity and more confidence and precision on the respiration rates and biomasses of fine roots.

Arbuscular mycorrhizal symbiosis can counterbalance the negative influence of the exotic tree species Eucalyptus camaldulensis on the structure and functioning of soil microbial communities in a sahelian soil

The hypothesis of the present study was that bacterial communities would differentiate under Eucalyptus camaldulensis and that an enhancement of arbuscular mycorrhizal (AM) density would minimize this exotic plant species effect. Treatments consisted of control plants, preplanting fertilizer application and AM inoculation. After 4 months of culture in autoclaved soil, E. camaldulensis seedlings were either harvested for growth measurement or transferred into containers filled with the same soil but not sterilized. Other containers were kept without E. camaldulensis seedlings. After 12 months, effects of fertilizer amendment and AM inoculation were measured on the growth of Eucalyptus seedlings and on soil microbial communities. The results clearly show that this plant species significantly modified the soil bacterial community. Both community structure (assessed by denaturing gradient gel electrophoresis profiles) and function (assessed by substrate-induced respiration responses including soil catabolic evenness) were significantly affected. Such changes in the bacterial structure and function were accompanied by disturbances in the composition of the herbaceous plant species layer. These results highlight the role of AM symbiosis in the processes involved in soil bio-functioning and plant coexistence and in afforestation programmes with exotic tree species that target preservation of native plant diversity.

Mycorrhizal status of Eucalyptus plantations in south China and implications for management

The aim of this study is to assess the mycorrhizal status of Eucalyptus plantations in south China and to determine the need for inoculation. In four provinces in south China, 155 plantations were sampled for sporocarps of ectomycorrhizal (ECM) fungi, spores of arbuscular mycorrhizal (AM) fungi, and mycorrhizas over 2 years. This study revealed a low above-ground diversity of ECM fungi consisting of 15 taxa fruiting beneath Eucalyptus plantations. The most common ECM genera were Scleroderma and Pisolithus, but they were infrequent. A total of 21 AM fungi, mostly Glomus species, were recognized from spores collected from eucalypt plantations. Four Glomus species were frequently present in soils, but spore density and relative abundance of AM fungi were generally low. Eucalypt roots from all plantation sites were poorly colonized by either ECM fungi or AM fungi. A bioassay with E. urophylla as a bait host, using soils collected from 11 eucalypt plantations, confirmed low levels of inoculum of both ECM and AM fungi in field soil. This is the first integrated study on the mycorrhizal status of eucalypt plantations in China. Findings from this research can be used to encourage adoption of mycorrhizal technology by eucalypt nurseries in the region. The potential of using spores of compatible ECM fungi or collections for forest nurseries is discussed.

Beneficial effect of saprobe and arbuscular mycorrhizal fungi on growth of Eucalyptus globulus co-cultured with Glycine max in soil contaminated with heavy metals

The effects of saprobe and arbuscular mycorrhizal (AM) fungi on growth, chlorophyll and N, P and K content of Eucalyptus globulus Labill. growing in soil contaminated by heavy metals in the presence or absence of Glycine max were investigated. Glomus mosseae and Glomus deserticola increased dry weight, shoot length, total N, P and K concentration and the quantity of chlorophyll in E. globulus shoots. The protection of Eucalyptus by AM fungi against the action of the heavy metals was more evident when this plant grew as an intercrop with soybean than as a monoculture. The presence of the saprobe fungi Fusarium concolor and Trichoderma koningii further enhanced shoot dry weight, N, P and K content of AM Eucalyptus. The co-inoculation of Eucalyptus with Glomus deserticola and T. koningii was more effective for Cd uptake. In addition, Glomus deserticola enhanced the amount of Pb absorbed by Eucalyptus plants. We showed that it is important to select the most efficient AM and saprobe fungi to stimulate plant growth in heavy-metal-contaminated soil and that the combination of both plays an important role in metal tolerance of Eucalyptus plants.

Degradation of eucalypt waste components by Lentinula edodes strains detected by chemical and near-infrared spectroscopy methods

There are many changes, both qualitative and quantitative, in eucalypt waste during growth and fructification of Lentinula edodes. Wet chemical analysis and near-infrared (NIR) spectroscopy were used in conjunction with multivariate regression and principal components analysis to monitor biodegradation of eucalyptus waste during growth of several L. edodes strains. Weight and component losses of eucalypt residue after biodegradation by L. edodes strains were compared for periods of 1 to 5 mo. Decrease in cellulose, hemicellulose, and lignin contents occurred, however it was not concomitant. Measurement of lignin degradation by NIR and wet chemical analysis indicated its attack in the early stages of biodegradation. Selective lignin degradation by L. edodes was observed up to 2 mo of biodegradation for strains DEBIQ and FEB-14. One group of degraded substrate was identified based on the principal component analysis (PCA) of the data on their biodegradation time. Samples treated for 5 months by L. edodes strains (DEBIQ, UFV or FEB-14) differed from other, but no discrimination was observed among them. By the end of 5 mo, NIR analyses showed decrease of about 18-47% cellulose, 35-47% polyose and 39-60% lignin. These data were used for comparison with those obtained by wet chemical method for the degradation of the substrate by other five L. edodes strains cultivated at the same conditions. NIR calibration developed in this study was proven to be perfectly suitable as an analytical method to predict the changes in lignocellulose composition during biodegradation.

Multiple gene genealogies reveal important relationships between species of Phaeophleospora infecting Eucalyptus leaves

The majority of Eucalyptus species are native to Australia, but worldwide there are over 3 million ha of exotic plantations, especially in the tropics and subtropics. Of the numerous known leaf diseases, three species of Phaeophleospora can cause severe defoliation of young Eucalyptus; Phaeophleospora destructans, Phaeophleospora eucalypti and Phaeophleospora epicoccoides. Phaeophleospora destructans has a major impact on seedling survival in Asia and has not, as yet, been found in Australia where it is considered a serious threat to the biosecurity of native eucalypts. It can be difficult to distinguish Phaeophleospora species based on symptoms and micromorphology and an unequivocal diagnostic tool for quarantine purposes would be useful. In this study, a multiple gene genealogy of these Phaeophleospora species and designed specific primers has been constructed to detect their presence from leaf samples. The phylogenetic position of these Phaeophleospora species within Mycosphaerella was established. They are closely related to each other and to other important Eucalyptus pathogens, Mycosphaerella nubilosa, Mycosphaerella cryptica and Colletogloeopsis zuluensis. The specific primers developed can now be used for diagnostic and screening purposes within Australia.

Ectomycorrhizal fungi of the Seychelles: diversity patterns and host shifts from the native Vateriopsis seychellarum (Dipterocarpaceae) and Intsia bijuga (Caesalpiniaceae) to the introduced Eucalyptus robusta (Myrtaceae), but not Pinus caribea (Pinaceae)

Ectomycorrhizal (ECM) fungi form highly diverse communities in temperate forests, but little is known about their community ecology in tropical ecosystems. Using anatomotyping and rDNA sequencing, ECM fungi were identified on root tips of the introduced Eucalyptus robusta and Pinus caribea as well as the endemic Vateriopsis seychellarum and indigenous Intsia bijuga in the Seychelles. Sequencing revealed 30 species of ECM fungi on root tips of V. seychellarum and I. bijuga, with three species overlapping. Eucalyptus robusta shared five of these taxa, whereas P. caribea hosted three unique species of ECM fungi that were likely cointroduced with containerized seedlings. The thelephoroid (including the anamorphic genus Riessiella), euagaric, boletoid and hymenochaetoid clades of basidiomycetes dominated the ECM fungal community of native trees. Two species of Annulatascaceae (Sordariales, Ascomycota) were identified and described as ECM symbionts of V. seychellarum. The low diversity of native ECM fungi is attributed to deforestation and long-term isolation of the Seychelles. Native ECM fungi associate with exotic eucalypts, whereas cointroduced ECM fungi persist in pine plantations for decades.

The biology of the Cryptococcus neoformans species complex

Cryptococcus neoformans is a major cause of fungal meningoencephalitis in immunocompromised patients. Despite recent advances in the genetics and molecular biology of C. neoformans, and improved techniques for molecular epidemiology, aspects of the ecology, population structure, and mode of reproduction of this environmental pathogen remain to be established. Application of recent insights into the life cycle of C. neoformans and its different ways of engaging in sexual reproduction under laboratory conditions has just begun to affect research on the ecology and epidemiology of this human pathogenic fungus. The melding of these disparate disciplines should yield rich dividends in our understanding of the evolution of microbial pathogens, providing insights relevant to diagnosis, treatment, and prevention.

A re-evaluation of the Cortinarius scobinaceus and Cortinarius impolitus complex in the Mediterranean area

We have conducted a taxonomic study of Cortinarius belleri, C. cistohelvelloides, C. impolitus and C. scobinaceus from material collected in Spain, France, Italy, Portugal and Morocco. Based on anatomy, morphology, ecology and distribution (geographical data) we recognize two species, C. impolitus and C. scobinaceus, and the new combination C. scobinaceus var. cistohelvelloides is made. Cortinarius belleri, C. cistohelvelloides, C. impolitus and C. scobinaceus have been typed, and a key for identification of these taxa is included.

Prescribed burning in a Eucalyptus woodland suppresses fruiting of hypogeous fungi, an important food source for mammals

Fruit bodies of hypogeous fungi are an important food source for many small mammals and are consumed by larger mammals as well. A controversial hypothesis that prescribed burning increases fruiting of certain hypogeous fungi based on observations in Tasmania was tested in the Australian Capital Territory to determine if it applied in a quite different habitat. Ten pairs of plots, burnt and nonburnt, were established at each of two sites prescribe-burnt in May 1999. When sampled in early July, after autumn rains had initiated the fungal fruiting season, species richness and numbers of fruit bodies on the burnt plots were extremely low: most plots produced none at all. Both species richness and fruit body numbers were simultaneously high on nonburnt plots. One of the sites was resampled a year after the initial sampling. At that time species richness and fruit body abundance were still significantly less on burnt plots than on nonburnt, but a strong trend towards fungal recovery on the burnt plots was evident. This was particularly so when numbers of fruit bodies of one species, the hypogeous agaric Dermocybe globuliformis, were removed from the analysis. This species strongly dominated the nonburnt plots but was absent from burnt plots in both years. The trend towards recovery of fruit body abundance in the burnt plots one year after the burn was much more pronounced with exclusion of the Dermocybe data. The Tasmanian-based hypothesis was based mostly on the fruiting of two fire-adapted species in the Mesophelliaceae. Neither species occurred on our plots. Accordingly, the results and conclusions of the Tasmanian study cannot be extrapolated to other habitats without extensive additional study. Implications for management of habitat for fungi and the animals that rely on the fungi as a food source are discussed.

Aurapex penicillata gen. sp. nov. from native Miconia theaezans and Tibouchina spp. in Colombia

Conidiomata of a fungus resembling Chrysoporthe cubensis, a serious canker pathogen of Eucalyptus spp. (Myrtaceae, Myrtales) in tropical and subtropical parts of the world, was found on Eucalyptus grandis in Colombia. Fruiting structures of the fungus could be distinguished from those of C. cubensis by their distinctly orange conidiomatal necks. This fungus also was found on several plant species native to Colombia including Tibouchina urvilleana, T. lepidota and Miconia theaezans (Melastomataceae, Myrtales). Morphological comparisons, as well as those based on sequences of the ITS1/ITS2 region of the ribosomal DNA repeat and the beta-tubulin gene, were used to characterize this fungus. Its pathogenicity was assessed on various plants from which it has been collected, either in field or greenhouse trials. Phylogenetic analyses showed that isolates reside in a clade distinct from the four clades accommodating Chrysoporthe, Cryphonectria, Endothia and Rostraureum. Members of this clade are distinguished by the presence of orange conidiomatal necks with black bases and a unique internal stromatal structure. No teleomorph has been found for this fungus, for which we have provided the name Aurapex penicillata gen. sp. nov. A. penicillata produced only small lesions after inoculation on young T. urvilleana, M. theaezans and E. grandis trees and appears not to be a serious pathogen.

Looking for sex in the fungal pathogens Cryptococcus neoformans and Cryptococcus gattii

Why are we interested in understanding the mode of reproduction being used by the fungal pathogens Cryptococcus neoformans and Cryptococcus gattii? Empirical evidence has finally supported the long-held assumption that, by increasing the rate of adaptive evolution, sex increases the chances of long-term survival. Understanding the ability of pathogenic organisms to adapt to diagnostic and treatment regimes is also important in the fight against the diseases caused by these organisms. This review looks at the different approaches used to identify population structure in C. neoformans and C. gattii. These are sexual species; however, recombination in natural populations has only recently been found. We highlight the importance of population selection and the value of both indirect molecular analysis and direct biological evidence for sexual recombination, when looking for the mode of reproduction in these fungal pathogens.

Selecting ectomycorrhizal fungi for inoculating plantations in south China: effect of Scleroderma on colonization and growth of exotic Eucalyptus globulus, E. urophylla, Pinus elliottii, and P. radiata

Plantation forestry with exotic trees in south China needs compatible symbionts to improve the growth of seedlings in nurseries and to enhance establishment and growth in the field. Scleroderma, a potentially suitable symbiont for inoculation, is not being used in containerized nurseries in the region due to poor knowledge of its host range. The ability of 15 collections of Scleroderma, nine from Australia and six from Asia, to colonize and promote growth of four important exotic plantation trees (Eucalyptus globulus Labill., Eucalyptus urophylla ST Blake, Pinus elliottii Engl., and Pinus radiata D. Don) was examined in a nursery potting mix. There was generally low host specificity of Scleroderma between tree genera. At 12 weeks after inoculation, 13 to 14 of the 15 spore collections formed ectomycorrhizas on seedlings of eucalypts or pines. The extent of colonization differed between spore treatments with two or four collections forming abundant mycorrhizas (>50% fine roots colonized) on E. globulus or E. urophylla, respectively, and three or five on P. radiata or P. elliottii, respectively. Three collections from Australia strongly colonized all hosts resulting in 26 to 100% of short roots being colonized. Chinese Scleroderma collections resulted in fewer mycorrhizas on eucalypts than on pines. Inoculation stimulated the growth (shoot height and dry weight) of eucalypt and pine seedlings by up to 105% where Scleroderma mycorrhizas developed. The results suggest that there is a need to source Scleroderma from outside China for inoculating eucalypts in Chinese nurseries whereas Chinese collections of Scleroderma could be used in pine nurseries. Further screening of Australian and Chinese Scleroderma should be performed in Chinese nurseries and in the field before final commercial decisions are made.

Influence of climatic conditions on the isolation of members of theCryptococcus neoformansspecies complex from trees in Colombia from 1992–2004

The aim of this retrospective study was to analyze the relationship between occurrence of the serotypes of the Cryptococcus neoformans species complex in tree samples and the climatic conditions registered during samplings in four cities of Colombia, between 1992 and 2004, by means of a logistic regression model and lagged Pearson correlations. During 97 collection dates, 8220 samples from different tree species were taken, of which 2.63% were positive: 56.5% yielded serotype B, 24.7% serotype C and 18.8% serotype A isolates. The prevalence of the serotypes varied among the cities. The results suggest that environmental climatic conditions, mainly humidity, temperature, evaporation and solar radiation, can affect the occurrence of the different serotypes in trees in a differential manner. These different climatic tolerances were reflected in the geographic distribution of the serotypes in Colombia. The climatic conditions for 15 days before the sampling date were correlated with positive or negative isolation of the different serotypes.

Two new Fusicoccum species from Acacia and Eucalyptus in Venezuela, based on morphology and DNA sequence data

Botryosphaeria spp. are common endophytes of woody plants, and they also include some serious pathogens of Eucalyptus and Acacia species. Numerous anamorphs have been associated with Botryosphaeria, of which the species Fusicoccum are amongst the most common. Here, we characterize two new Fusicoccum species, isolated from Eucalyptus and Acacia trees in Venezuela, based on morphological features in culture and comparisons of DNA sequence data. The two taxa named Fusicoccum andinum and F. stromaticum spp. nov, reside in two well-supported clades (BS values = 100%) based on a combined data set of the ITS of the rDNA operon and translation elongation factor 1-alpha (EF1- alpha) gene sequences. The conidia of F. andinum are unusually large amongst Botryosphaeria anamorphs, and peripherally resemble those of B. mamane and B. melanops. F. stromaticum is characterized by large conidiomata in cultures, growth at 35 degrees C and slightly thickened conidial walls, which is different to most other Fusicoccum spp. No teleomorphs were observed for these fungi, but DNA sequence data show that they are anamorphs of Botryosphaeria.

Complete Bioconversion of Hemicellulosic Sugars From Agricultural Residues Into Lactic Acid by Lactobacillus pentosus

On the basis of previous knowledge, different agroindustrial wastes were submitted to dilute-acid hydrolysis with H2SO4 to obtain hemicellulosic sugars and then employed for lactic acid production by Lactobacillus pentosus. Toxic compounds released from lignin did not affect lactic acid fermentation when hydrolysates from trimming vine shoots, barley bran husks, or corncobs were employed as carbon source, and complete bioconversion of hemicellulosic sugars was achieved. Nevertheless, Eucalyptus globulus hydrolysates had to be submitted to a detoxification process with activated charcoal. Maximum lactic acid concentration (33 g/L) was reached employing barley bran hydrolysates, whereas corncobs, trimming vine shoots, and detoxified E. globulus hydrolysates yielded 26, 24, and 14.5 g/L of lactic acid, respectively. The maximum product yield from pentoses (0.76 g/g) was achieved using hydrolysates from trimming vine shoots, followed by hydrolysates from detoxified E. globulus (0.70 g/g), barley bran (0.57 g/g), and corncob (0.53 g/g). These results confirm that L. pentosus can be employed to ferment hemicellulosic sugars (mainly xylose, glucose, and arabinose) from acid hydrolysates of most agricultural residues without appreciable substrate inhibition.

Isolation ofCryptococcus neoformansvar.neoformansserotype D from Eucalypts in South Brazil

Cryptococcus neoformans causes the second most common opportunistic infection in patients with AIDS. In Brazil, 4.5% of the AIDS-related opportunistic infections are caused by C. neoformans and all varieties are recognized as etiological agents of cryptococcosis. This pathogen is a ubiquitous environmental yeast, commonly associated with avian excreta and decaying wood, especially Eucalypt species. The aim of the present study was to search for C. neoformans in Eucalypts and analyze the genotypic diversity of the obtained isolates by RAPD and PCR fingerprinting. All obtained isolates have been C. neoformans var. neoformans, serotype D molecular type VNIV. Serotype D, was isolated from 3 (37.5%) out of 8 cities surveyed in the South Brazilian state Rio Grande do Sul. Nine (9%) out of 99 environmental samples were obtained from Eucalypt species, Eucalyptus calmadulensis and Eucalyptus tereticornis. Molecular analysis using RAPD and PCR-fingerprinting revealed very little genetic diversity in the obtained cryptococcal serotype D isolates. To our knowledge this is the first report of the isolation of serotype D from Eucalyptus trees in Brazil. More studies are required in order to establish the ecological significance of this finding.

Photosynthesis of Eucalyptus globulus with Mycosphaerella leaf disease

Mycosphaerella leaf disease (MLD) is a major cause of foliage damage in Eucalyptus globulus plantations. Our study is the first to describe the physiological effects of MLD on E. globulus leaves. It involved measurements on both field and potted plants. Changes in photosynthetic parameters in response to MLD were quantified in a study using gas exchange techniques. There was a negative linear relationship between light-saturated photosynthesis (A(max)) and leaf-level damage from MLD. Reductions in A(max) were proportionally greater than might be expected from the reduction in green leaf area as a result of the disease, indicating that asymptomatic tissue also was affected by MLD. The reductions in A(max) were not related to increases in stomatal resistance, but were a result of reduced activity of ribulose bisphosphate carboxylase (Rubisco) and changes in the capacity for ribulose bisphosphate (RuBP) regeneration. Changes in mesophyll resistance to CO2 were also implicated. The effect of MLD was similar at different sites and irrespective of tree-level infection, suggesting a general leaf-level response of E. globulus to MLD.

Clonality and recombination in genetically differentiated subgroups of Cryptococcus gattii

Cryptococcus gattii is a pathogenic yeast that together with Cryptococcus neoformans causes cryptococcosis in humans and animals. High numbers of viable C. gattii propagules can be obtained from certain species of Australian Eucalyptus camaldulensis trees, and an epidemiological link between Eucalyptus colonization and human exposure has been proposed. However, the highest prevalence of C. gattii cryptococcosis occurs in Papua New Guinea and in regions of Australia where the eucalypt species implicated to date are not endemic. This study investigated the population structure of three geographically distinct clinical and veterinary populations of C. gattii from Australia and Papua New Guinea. All populations that consisted of a genotype found frequently in Australia (VGI) were strongly clonal and were highly differentiated from one another. Two populations of the less common VGII genotype from Sydney and the Northern Territory had population structures inferring recombination. In addition, there was some evidence of reduced genetic differentiation between these geographically remote regions. In a companion study presented in this issue, VGII isolates were overwhelmingly more fertile than those of the VGI genotype, giving biological support to the indirect assessment of sexual exchange. It appears that the VGI genotype propagates clonally on eucalypts in Australia and on an unknown substrate in Papua New Guinea, with infection initiated by an unidentified infectious propagule. VGII isolates are completing their life cycles and may be dispersed via sexually produced basidiospores, which are also likely to initiate respiratory infection.

Botryosphaeria species from Eucalyptus in Australia are pleoanamorphic, producing Dichomera synanamorphs in culture

Species within the genus Botryosphaeria include some of the most widespread and important pathogens of woody plants, and have been the focus of numerous taxonomic studies in recent years. It is currently accepted that anamorphs of Botryosphaeria belong to two distinct genera, Fusicoccum and Diplodia. Species within the genus Fusicoccum commonly produce aseptate, hyaline conidia. In the present study, fungi were isolated from foliage and wood of Eucalyptus in native forests and plantations in Australia. Although these fungi produced Dichomera anamorphs in culture, they clustered within the Fusicoccum clade of Botryosphaeria based on their ITS sequence data. Four species, Botryosphaeria dothidea, B. parva, B. ribis and B. australis produced Dichomera conidia in culture. The Dichomera synanamorphs are described for these four species of Botryosphaeria. In addition, falling within the Fusicoccum clade of Botryosphaeria, two species were found to be distinct from previously described Botryosphaeria spp. based on their ITS sequences, but synonymous with D. versiformis and D. eucalypti. These observations are currently unique to isolates from host trees within the genus Eucalyptus in Australia, and the pleoanamorphic nature of these species is discussed.

PCR-identification of Mycosphaerella species associated with leaf diseases of Eucalyptus

A PCR-based technique based on the ITS1-5.8s-ITS2 domain of the rRNA gene for identifying five species associated with Mycosphaerella leaf disease (MLD) of eucalypts was developed. Primer pairs MC2F and MC2R; ML1F and ML1R; MM1F and MM1R; MN1F and MN1R; and MP1F and MP1R amplified a product for DNA extracted from their single target species, those being M. cryptica, M. lateralis, M. marksii, M. nubilosa and M. parva, respectively. The possibility of false positive amplification by each primer pair was tested in reactions with DNA extracts from 16 other Mycosphaerella species associated with eucalypts and against non-infected Eucalyptus globulus leaves. Under the PCR conditions used, there were no false positive amplifications of the 16 non-target Mycosphaerella species, or from non-symptomatic E. globulus leaves for the primer pairs ML1F and ML1R; MM1F and MM1R; MN1F and MN1R; and MP1F and MP1R. The primer pair MC2F and MC2R amplified a 402 nt product from both the target M. crvptica and non-target M. nubilosa. However, these two species were differentiated by digesting the product with the restriction enzyme Sacc II which resulted in a single 402 nt product for M. cryptica, and two products of 78 and 324 nt for M. nubilosa. All of the primers were able to detect their target Mycosphaerella species from Eucalyptus globulus lesions. PCR reactions with these primers on DNA extracted from Mycosphaerella lesions confirmed the presence of all five species from leaf material collected from three plantations in Western Australia.

[Isolation of Cryptococcus gattii serotype B from detritus of Eucalyptus trees in Colombia]

INTRODUCTION

Cryptococcus gattii serotype B has been associated with several species of trees in tropical and subtropical regions. Serotype B has been found to be the second most frequently isolated from patients in Colombia, but it has not been isolated from the environment. Therefore, a study was designed to sample plant material from a forest in the province of Cundinamarca, with the aim of establishing the presence and distribution of the C. neoformans complex, specially serotype B. In addition, isolates were evaluated for several phenotypic characteristics associated with virulence.

METHODOLOGY

During February and March, 2003, 4 separate sample collections were made. One hundred sixty-seven samples were collected from detritus of eucalyptus and 28 samples from other species of trees. All were processed using the conventional procedure and plated on selective media. The following parameters were measured: cellular and capsular sizes in the filtrates, growth at 37 degrees C, virulence in a mouse animal model system, and mating type as detected by PCR.

RESULTS

Cryptococcus gattii serotype B was isolated from 46 eucalyptus samples (27.5%). The cellular size in the filtrates ranged from 3.10 to 4.15 microm and the capsular size from 0.30 and 0.46 microm. The 46 isolates grew at 37 degrees C, but none of them caused the death in the animals during 70-day observation period. All isolates were of mating type a.

CONCLUSIONS

This constitutes the first report of the isolation of serotype B, mating type a, from eucalyptus detritus in Colombia.

Characterization of Cryptococcus neoformans isolated from urban environmental sources in Goiânia, Goiás State, Brazil

Cryptococcus neoformans is an opportunistic fungal pathogen that causes meningoencephalitis as the most frequent clinical presentation in immunocompromised patients, mainly in people infected by HIV. This fungus is an environmental encapsulated yeast, commonly found in soil enriched with avian droppings and plant material. A total of 290 samples of pigeon and the other avian droppings, soil, ornamental trees and vegetable material associated with Eucalyptus trees were collected to study environmental sources of Cryptococcus species in Goiânia, Goiás State. The determination of varieties, serotypes and the susceptibility in vitro to fluconazole, itraconazole and amphotericin B of C. neoformans isolates were performed. C. neoformans var. grubii (serotype A) was found in 20.3% (36/177) of pigeon dropping samples and in 14.3% (5/35) of samples of Eucalyptus. None of the environmental isolates of C. neoformans showed in vitro resistance to three antifungal agents. The knowledge of major route for human cryptococcal infection (inhalation of infectious particles from saprophytic sources) and a total of 60 C. neoformans isolates obtained from AIDS patients with cryptococcal meningitis between October 2001 and April 2002 justify the study of the habitats of these yeasts as probable sources of cryptococcosis in this city.

Distribución ambiental de Cryptococcus neoformans en el departamento de Cundinamarca-Colombia

Cryptococcus neoformans is an opportunistic fungal pathogen that could cause infection in patients with immunodeficiency and healthy patients. The AIDS epidemic has shown the importance of studying the ecology and epidemiology of this fungus. The aim of this investigation was to determine if there was a relationship between the environmental distribution of the different varieties of C. neoformans and the climate zones in two transects located in department of Cundinamarca, in Colombia. For the isolation and identification of the yeast, conventional phenotypic methods were used and it was determined the population density (CFU/g of sample) and which was the variety of greater prevalence in each altitudinal rank. A total of 765 samples, from 26 municipalities were collected; of these 146 corresponded to pigeon droppings (Columba livia), 437 to Eucalyptus detritus (Eucalyptus camaldulensis and related species) and 182 to detritus of almond trees (Terminalia cattapa). C. neoformans was isolated from 46% of the studied municipalities, in both transects and the climate zones: warm, temperate and cold. The results indicated that the greater frequency of positive isolations came from the last climate zone (cold). The population density in pigeon excrements oscillated between 50 and 9.2 x 1,000,000, in eucalyptus between 500 and 10 x 1,000,000 and in almond trees was 50 CFU/g. Of 100,000 positive isolations 31% were serotype A, 59% serotype B and 10% serotype C; 96% of the isolates grew to 37 degrees C and all showed capsule. In conclusion, C. neoformans prevails in the three habitats studied but it showed a predilection for the cold thermal floor; the population densities did not allow defining a standard pattern of occurrence.

A specific primer PCR and RFLP assay for the rapid detection and differentiation in planta of some Mycosphaerella species associated with foliar diseases of Eucalyptus globulus

It is difficult to accurately identify Mycosphaerella species associated with leaf diseases of Eucalyptus based on morphological characters, as there is considerable overlap between very similar species and subspecies, and isolation from the host is not easy. Thus, a PCR and RFLP assay based on the ITS region of nr DNA was developed for the rapid detection and differentiation of M. nubilosa, M. cryptica and two non-sporing unidentified Mycosphaerella species isolated from the foliage of trees in resistant and susceptible families of E. globulus in a seed orchard at Kinglake West, Victoria, Australia. The M. nubilosa primer pair MNF/MNR was highly specific. A PCR-RFLP system based on the primer pair MCF/MCR, coupled with two restriction enzymes (DdeI and Tru1 I), differentiated M. cryptica, M. nubilosa, M. tasmaniensis and M. aff. vespa. One of the unidentified field-isolated Mycosphaerella species was identified as M. grandis on the basis of ITS sequence data while the other species remains unidentified. A PCR-RFLP system based on the primer pair U1F/U1R, coupled with the restriction enzyme StyI, differentiated between the two unidentified species. Unexpectedly, unlike isolation and culture studies, these assays detected M. nubilosa, M. cryptica and M. grandis in all single lesions examined on both juvenile and adult leaves, and on both highly resistant and highly susceptible E. globulus trees at this site.

Transcript patterns associated with ectomycorrhiza development in Eucalyptus globulus and Pisolithus microcarpus

Regulated gene expression is an important mechanism for controlling ectomycorrhizal symbiosis development. This study aimed to elucidate the coordination between development of mycorrhiza and the differential gene expression in both partners. We analysed RNA levels from sequential samples of symbiotic tissues of Eucalyptus globulus bicostata and the basidiomycete Pisolithus microcarpus progressing through ectomycorrhiza development using cDNA arrays. We derived groups of coordinately expressed genes using hierarchical and nonhierarchical clustering algorithms. Five major distinct temporal patterns of induction/repression were observed with distinct groups of early, middle-, and late-transcriptionally responsive genes to symbiosis formation. At earliest stages, the differentially expressed fungal genes included cell wall symbiosis-regulated proteins, hydrophobins and mannoproteins, whereas transcripts coding for defense-related proteins were upregulated in plant tissues. Middle- and late-transcriptionally responsive genes coded enzymes of glycolysis, tricarboxylic acid cycle and amino acid biosynthesis, as well as protein synthesis, hormone metabolism and signal transduction components. This investigation confirms and extends earlier results which found that changes in morphology associated with mycorrhizal development were accompanied by changes in transcript patterns, but no ectomycorrhiza-specific genes were detected.

Effect of cereal brans on Lentinula edodes growth and enzyme activities during cultivation on forestry waste

AIMS

To develop strategies for increasing the growth of Lentinula edodes in eucalyptus residues. To this end, we have examined the effects of cereal brans additions on production of mycelial biomass and enzymes.

METHODS AND RESULTS

Three isolates of the mushroom shiitake, L. edodes (Berk. Pegler), were evaluated for enzyme and ergosterol production on eucalyptus residue supplemented with 5, 10, 15 and 20% (w/w) of soya, wheat or rice brans. Nitrogen imput on eucalyptus residues accelerated mycelial growth by supplying the L. edodes with this limiting nutrient. High levels of enzymes activities were produced in eucalyptus residues supplemented by soya bran. Comparison of cellulose and xylanase production with manganese peroxidase (MnP) at 20% soya bran indicated that hydrolytic enzymes, but oxidative enzymes were reduced.

CONCLUSIONS

Mycelial growth measurements revealed that eucalyptus residues supplemented with cereal brans supported fast growth of L. edodes, indicating that mycelium extension is related to the bioavailability of nitrogen. The type and concentration of nutrient supplement has a considerable effect both on substrate colonization and on the type of hydrolytic and oxidative enzymes produced. These characteristics may be useful for mushroom growing.

SIGNIFICANCE AND IMPACT OF THE STUDY

Lentinula edodes is commercially important for edible mushroom production and supplements which enhance growth and enzymes production might also be beneficial for mushroom yields.

Species richness and seasonal abundance of ectomycorrhizal fungi in plantations of Eucalyptus dunnii and Pinus taeda in southern Brazil

The abundance and diversity of ectomycorrhizal fungi (EMF) was assessed based on the collection of basidiocarps during 12 months comprising the spring of 1995, and the summer, autumn, and winter of 1996, in three stands of young, middle-aged, and rotation age plantations of Pinus taeda and Eucalyptus dunnii, in the state of Santa Catarina, southern Brazil. A total of 3,085 collections yielded 34 presumed EMF taxa in ten genera, including mushroom-like and sequestrate species. Fruiting patterns of EMF differed with host and season, and host specificity was apparent in some. The overall relative importance (RI) and the Shannon diversity index (H) suggested that stands of E. dunnii had a more diverse aboveground EMF community than those of P. taeda. Overall, species of Scleroderma and Laccaria were not only the most abundant but also had the highest biomass values. The results show that a small number of species of abundant biomass and a larger number of species of less-abundant biomass characterize each forest class.

Growth and survival of seedlings of native plants in an impoverished and highly disturbed soil following inoculation with arbuscular mycorrhizal fungi

We investigated whether arbuscular mycorrhizas influenced growth and survival of seedlings in an extremely impoverished and highly disturbed soil. Seedlings of four plants species native to the site were either inoculated with native sporocarpic arbuscular mycorrhizal (AM) fungi or fertilised prior to transplanting, and followed over 86 weeks at the site. One treatment was also irrigated with N-rich leachate from the site. In a laboratory experiment, seedlings were fertilised with excess P for 6 weeks, and location of the P store determined. Growth and survival of AM and fertilised seedlings were similar at the site. Inoculated mycorrhizal fungi and roots appeared to extend into the surrounding soil together. P concentration in leaves of all plants was extremely low. Irrigation with leachate increased growth of seedlings. In the laboratory experiment, significantly more P was stored in roots than shoots. We suggest that successful revegetation of extremely disturbed and impoverished sites requires selection of mycorrhizal fungi and plants to suit the edaphic conditions and methods of out-planting.

Serotype and PCR-fingerprints of clinical and environmental isolates of Cryptococcus neoformans in Chiang Mai, Thailand

From May 1999 to April 2000, serotypes of clinical and environmental isolates of Cryptococcus neoformans were studied in Chiang Mai province, northern Thailand. Three hundred and eighty-five environmental samples, of which 100 were dove droppings, 55 pigeon droppings and 230 eucalyptus flower, were collected from 7 Amphoes in Chiang Mai. C. neoformans was isolated from 45 of 100 (45.0%) dove dropping samples, 9 of 55 (16.4%) pigeon dropping samples and 2 of 230 (0.9%) eucalyptus flower samples. Serotypes of 56 environmental isolates and 75 clinical isolates of C. neoformans,obtained during the same period, were determined by the slide agglutination test. Fifty-six environmental and 74 clinical isolates belonged to C. neoformans serotype A (C. neoformans var. grubii), and only one clinical isolate belonged to C. neoformans serotype AD. The isolation of C. neoformans var. grubii from eucalyptus flower samples suggests contamination of avian droppings. PCR-fingerprinting, using (GACA)4 as a primer, discriminated 131 clinical and environmental isolates into 2 groups (group I and II). Seventy-five clinical and 54 environmental isolates were of group I, which had two major specific bands of approximately 1,250 and 960 base pairs. Two environmental isolates, one from pigeon excreta and the other from a eucalyptus flower sample were of group II, which had two major specific bands of approximately 1,180 and 500 base pairs.

No significant contribution of arbuscular mycorrhizal fungi to transfer of radiocesium from soil to plants

The diffuse pollution by fission and activation products following nuclear accidents and weapons testing is of major public concern. Among the nuclides that pose a serious risk if they enter the human food chain are the cesium isotopes 137Cs and 134Cs (with half-lives of 30 and 2 years, respectively). The biogeochemical cycling of these isotopes in forest ecosystems is strongly affected by their preferential absorption in a range of ectomycorrhiza-forming basidiomycetes. An even more widely distributed group of symbiotic fungi are the arbuscular mycorrhizal fungi, which colonize most herbaceous plants, including many agricultural crops. These fungi are known to be more efficient than ectomycorrhizas in transporting mineral elements from soil to plants. Their role in the biogeochemical cycling of Cs is poorly known, in spite of the consequences that fungal Cs transport may have for transfer of Cs into the human food chain. This report presents the first data on transport of Cs by these fungi by use of radiotracers and compartmented growth systems where uptake by roots and mycorrhizal hyphae is distinguished. Independent experiments in three laboratories that used different combinations of fungi and host plants all demonstrated that these fungi do not contribute significantly to plant uptake of Cs. The implications of these findings for the bioavailability of radiocesium in different terrestrial ecosystems are discussed.

Genetic variability and taxonomic position of ectomycorrhizal fungus Pisolithus from India

Eight ectomycorrhizal fungal isolates of Pisolithus associated with Eucalyptus species in different parts of India were collected and the genetic variability of these isolates was studied by ITS-RFLP and ITS sequencing. All the isolates showed same RFLP patterns with each restriction enzyme, indicating all these isolates of Pisolithus are of the same genotype. The sequence comparison of KN6 of Indian isolate showed high sequence similarities with the isolates of Pisolithus associated with Eucalyptus from Australia. Phylogeny analysis showed that all the isolates compared in this study clustered into four main groups The Indian isolate (KN6) clustered with Pisolithus albus isolates of group I, which are associated with Eucalyptus. These results suggested that Pisolithus isolates found in India are P. albus.