Mycelial Mass Research Articles

First Report of Pythium aphanidermatum on Basella rubra in Japan.

Basella rubra L. (Indian spinach, Japanese name Tsurumurasaki) is cultivated worldwide as an ornamental and its aerial parts are consumed as a vegetable and health food. A severe rot of leaves, stems, and roots was found on B. rubra cv. Midori grown in a commercial field at Naruto-City (34°11'N, 134°36(E) in Tokushima Prefecture, Japan from May to September 2004. More than 50% of approximately 2,100 plants in the field were destroyed by the disease. Soft, black lesions appeared initially at the base of the stems in 2- to 5-month-old plants and enlarged gradually upward and downward within 2 days after plant injury caused by heavy rainfall. A fluffy, white mass of mycelium appeared on the surface of lesions under moist conditions. A Pythium species was routinely isolated from rotted stems and roots and identified as Pythium aphanidermatum (Edson) Fitzpatrick on the basis of its morphology on a grass leaf water culture (2). Characteristics of isolate OPU743 (NBRC No. 101556, MAFF No. 239847) included hyphae as much as 10 μm wide, terminal oogonia 17.8 to 28.8 μm in diameter, and monoclinous or diclinous antheridia 8.8 to 10.9 μm wide, either terminal or intercalary, with one or rarely two per oogonium. Oospores were aplerotic, 13.5 to 22.6 μm in diameter. Sporangia were terminal or occasionally intercalary, and either inflated filamentous hyphae or complexes of swollen hyphal branches were present in cultures. Cardinal temperatures for growth on potato carrot agar were 10°C minimum, 37°C optimum, and 40°C maximum with a daily radial growth rate of 32.9 mm at 25°C. Pathogenicity tests were conducted on potted 3-month-old B. rubra (cv. Midori). A wound (1 mm deep and 5 mm long made by a razor) on the surface of the stem of the plant was inoculated with an 8-mm-diameter agar disk of isolate OPU743 (grown at 25°C for 48 h on potato dextrose agar) attached to a stem of the plant using a paraffin film. The inoculated plants were placed in transparent plastic bags and kept in a growth chamber at 24 to 26°C with continuous light (82 to 126 μmol·m-2·s-1). The experiment was done four times with three plants in each experiment. The same number of plants was used for the noninoculated control. Dark brown rot of stems and leaves developed on 66.7% of inoculated plants within 2 days after inoculation. P. aphanidermatum reisolated from diseased tissues was morphologically identical to the original isolate OPU743. Noninoculated control plants showed no symptoms. P. aphanidermatum has been described on B. rubra in Brazil (1), but has not been reported from other regions of the world. To our knowledge, this is the first report of P. aphanidermatum on B. rubra in Japan.

Scab of Balsam Pear (Momordica charantia) Caused by Cladosporium cucumerinum in Korea

During winter season of 2004 to 2006, a scab disease on balsam pear (Momordica charantia) caused by Cladosporium cucumerinum was observed in Daesan-myon, Changwon-city, Gyeongnam province, Koyea. The disease symptom started with small dark brown speck on the fruits and leaves then the lesions expanded and spreaded irregularly. The aggregated mycelial mass and conidia of the fungus formed sooty scab. The colony of purely isolated fungus grew in greenish black to velvety on potato dextrose agar (PDA). Conidia were ellipsoidal, fusiform or subspherical, mostly one-celled but occasionally septated and <TEX>$3{\sim}32{\times}2{\sim}6{\mu}m$</TEX> in size. The conidiophores were erected and had long branch, chains pale olivaceous brown in color and <TEX>$6{\times}280{\mu}m$</TEX> in size. Ramoconidia were <TEX>$10{\sim}34{\times}3{\sim}8{\mu}m$</TEX> in size. The fungus was identified as Cladosporium cucumerinum based on the morphological characteristics. The pathogenicity of the fungus was confirmed according to Koch's postulate. The optimum temperature of the isolate was about <TEX>$20^{\circ}C$</TEX>. This is the first report on scab of balsam pear caused by C. cucumerinum in Korea.

A strategy for recovering high quality genomic DNA from a large number of Phytophthora isolates

We present a strategy to recover high molecular weight genomic DNA from large numbers of isolates of Phytophthora. Included are steps for generating mycelial mass in 24-well reuseable deep well plates, efficient lyophilization and disruption of the mycelium and genomic DNA extraction with 96-well glass fiber filter plates. The resulting DNA is consistently high molecular weight and is suitable for applications that require high quality DNA such as AFLP analysis and TILLING. A single operator easily can manage mycelium preparation and/or DNA extraction from 384 isolates in a single day and this approach might be useful for other fungi or fungi-like organisms that can be grown in liquid media.

A strategy for recovering high quality genomic DNA from a large number of Phytophthora isolates

We present a strategy to recover high molecular weight genomic DNA from large numbers of isolates of Phytophthora. Included are steps for generating mycelial mass in 24-well reuseable deep well plates, efficient lyophilization and disruption of the mycelium and genomic DNA extraction with 96-well glass fiber filter plates. The resulting DNA is consistently high molecular weight and is suitable for applications that require high quality DNA such as AFLP analysis and TILLING. A single operator easily can manage mycelium preparation and/or DNA extraction from 384 isolates in a single day and this approach might be useful for other fungi or fungi-like organisms that can be grown in liquid media.

Application of response surface methodology for optimization of important parameters in decolorizing treated distillery wastewater using Aspergillus fumigatus UB2 60

Distillery wastewater causes many environmental problems and colored substances must be removed from it before discharge into the environment. Decolorization of anaerobically treated distillery wastewater was therefore studied using locally isolated Aspergillus fumigatus . As cultural conditions are very important for the decolorization process, the combined effect of initial maltose concentration, pH and mycelial mass was studied using response surface methodology. A central composite design for the three variables was employed to study the combined effect on decolorization efficiency of distillery wastewater. The optimum initial maltose concentration was found to be 15.13 g/l, the optimum pH was 5.57 and the optimum mycelial mass 2.57 g/l.

Co-production of ligninolytic enzymes byPleurotus pulmonarius on wheat bran solid state cultures

In this paper, the production of biomass and ligninolytic enzymes by the white-rot fungus Pleurotus pulmonarius (Fr.) Quélet cultured on wheat bran at high initial moisture was evaluated. When the initial moisture was lower than 86%, the fungal hyphae penetrated into and bound tightly to the solid-substrate particles. When the moisture was equal or higher than 86%, the growth was characterized by formation of a large mycelial mass above the substrate (surface growth). In this case, the mycelial mass could be easily separated from the residual solid substrate and quantified by gravimetric analysis. The fungus produced 0.32 g of dry mycelial mass per g of dry substrate after 15 days of cultivation. Analysis of the residual substrate showed that growth was mainly due to the consumption of soluble proteins and carbohydrates. The condition of high initial moisture strongly promoted the expression of laccase (up to 24,000 U per g of substrate or 78,000 U per g of dry fungal biomass), while the production of manganese peroxidase was negatively affected. In fact, manganese peroxidase was maximally produced when the initial moisture was 75% (2,000 U per g of substrate). The production of other enzymes, such as polysaccharidases and proteases, was not significantly affected by the initial moisture.

Cellulase production by Penicillium echinulatum on lactose

The inducer effect of lactose on cellulase activity in Penicillium echinulatum 9A02S1 was studied. Submerged cultivation was performed using different concentrations of lactose and cellulose, in which the pH, mycelial mass, soluble proteins, filter paper activity (FPA), and activity of beta-glucosidases were measured. The cultures containing lactose only presented low FPAs (0.1 FPU/ml). The cultures with associated cellulose and lactose and those containing cellulose only presented similar enzymatic activities (1.5 FPU/ml), suggesting the possibility of up to 75% reduction in the cellulose concentration. In relation to the beta-glucosidases, increasing the lactose/cellulose ratio results in a proportional increase of enzymatic activity. In the cultures using both inducers, there is a longer duration of the acid phase in relation to treatments using only cellulose or lactose, indicating diauxia and catabolic repression.

SENSITIVITY OF ERICOID MYCORRHIZAL FUNGI AND MYCORRHIZAL CALLUNA VULGARIS TO COPPER MINE SPOIL FROM AVOCA, COUNTY WICKLOW

Ericoid mycorrhizal fungi were isolated from roots of Calluna vulgaris collected from mine spoil at abandoned copper mines at Avoca, County Wicklow, Ireland, and Parys Mountain, Anglesey, Wales. Two isolates were morphologically identical to Hymenoscyphus ericae and formed typical ericoid mycorrhizal associations. Four fungal isolates— the two mine-site isolates and two H. ericae isolates (obtained from uncontaminated sites) were grown in liquid media containing elevated levels of Cu and Zn. All isolates were determined to have a low sensitivity to these metals, with EC₅₀ values (concentration of metal causing 50% reduction in mycelial dry mass) in the range 0.3-0.9mM Cu and 1.2-5.5mM Zn, but there were differences in metal sensitivity between isolates. There was a significant decline in the tolerance of each isolate to increasing concentrations of mine spoil (up to 10% in the agar medium). Mycorrhizal amelioration of heavy-metal toxicity was determined by growing mycorrhizal (M) and non-mycorrhizal (NM) rooted cuttings of C. vulgaris on mine spoil. Rooted cuttings obtained from an uncontaminated site showed no response to mycorrhizal colonisation. However, C. vulgaris obtained from the Avoca site and inoculated with H. ericae performed better than NM plants. The improved growth of these plants was associated with a reduction in Cu within the host's shoot. Inoculation of C. vulgaris with an ericoid mycorrhizal fungus isolated from the Avoca mine site also reduced Cu accumulation within shoots but there was no change in the growth and Zn accumulation of C. vulgaris on mine spoil. Results are discussed in relation to the potential benefit of the ericoid mycorrhizal association to C. vulgaris at metal contaminated sites.

Sensitivity of Ericoid Mycorrhizal Fungi and Mycorrhizal &lt;i&gt;Calluna vulgaris&lt;/i&gt; to Copper Mine Spoil from Avoca, County Wicklow

Ericoid mycorrhizal fungi were isolated from roots of Calluna vulgaris collected from mine spoil at abandoned copper mines at Avoca, County Wicklow, Ireland, and Parys Mountain, Anglesey, Wales. Two isolates were morphologically identical to Hymenoscyphus ericae and formed typical ericoid mycorrhizal associations. Four fungal isolates? the two mine-site isolates and two H. ericae isolates (obtained from uncontaminated sites) were grown in liquid media containing elevated levels of Cu and Zn. All isolates were determined to have a low sensitivity to these metals, with EC50 values (concentration of metal causing 50% reduction in mycelial dry mass) in the range 0.3-0.9mM Cu and 1.2-5.5mM Zn, but there were differences in metal sensitivity between isolates. There was a significant decline in the tolerance of each isolate to increasing concentrations of mine spoil (up to 10% in the agar medium). Mycorrhizal amelioration of heavy-metal toxicity was determined by growing mycorrhizal (M) and non-mycorrhizal (NM) rooted cuttings of C. vulgaris on mine spoil. Rooted cuttings obtained from an uncontaminated site showed no response to mycorrhizal colonisation. However, C. vulgaris obtained from the Avoca site and inoculated with H. ericae performed better than NM plants. The improved growth of these plants was associated with a reduction in Cu within the host's shoot. Inoculation of C. vulgaris with an ericoid mycorrhizal fungus isolated from the Avoca mine site also reduced Cu accumulation within shoots but there was no change in the growth and Zn accumulation of C. vulgaris on mine spoil. Results are discussed in relation to the potential benefit of the ericoid mycorrhizal association to C. vulgaris at metal contaminated sites. Brian R. Gibson, Division of Food Sciences, School of Biosciences,

On-line estimation of cell growth from agitation speed in DO-stat culture of a filamentous microorganism,Agaricus blazei

A simple, but effective on-line method for estimating the mycelial cell mass concentration from agitation speed data, a most readily-available process variable, has been developed for DO-stat cultures ofAgaricus blazei. The dynamic change of dissolved oxygen concentration (DOC) in the initial transient period and the change in yield were considered in the development of the estimation algorithm or estimator. Parameters in the estimation algorithm were calculated from the agitation speed data at 20% of DOC. The proposed estimator could accurately predict the cell mass concentration regardless of DOC levels in the tested range of 10–40%, showing a good extrapolation capability.

Factors Influencing Development of Root Rot on Ginseng Caused by Cylindrocarpon destructans

ABSTRACT The fungus Cylindrocarpon destructans (Zins) Scholten is the cause of root rot (disappearing root rot) in many ginseng production areas in Canada. A total of 80 isolates of C. destructans were recovered from diseased roots in a survey of ginseng gardens in British Columbia from 2002-2004. Among these isolates, 49% were classified as highly virulent (causing lesions on unwounded mature roots) and 51% were weakly virulent (causing lesions only on previously wounded roots). Pectinase and polyphenoloxidase enzymes were produced in vitro by C. destructans isolates when they were grown on pectin and phenol as a substrate, respectively. However, highly virulent isolates produced significantly (P < 0.001) higher enzyme levels compared with weakly virulent isolates. Histopathological studies of ginseng roots inoculated with a highly virulent isolate revealed direct hyphal penetration through the epidermis, followed by intracellular hyphal growth in the cortex. Subsequent cell disintegration and accumulation of phenolic compounds was observed. Radial growth of highly and weakly virulent isolates on potato dextrose agar was highest at 18 and 21 degrees C, respectively and there was no growth at 35 degrees C. Mycelial mass production was significantly (P </= 0.01) lower at pH 7.0 compared with pH 5.0. To study the effects of pH (5.0 and 7.0) and wounding on disease development, ginseng roots were grown hydroponically in Hoagland's solution. Lesions were significantly larger (P < 0.001) at pH 5.0 compared with pH 7.0 and wounding enhanced disease by a highly virulent isolate at both pHs. In artificially infested soil, 2-year-old ginseng roots were most susceptible to Cylindrocarpon root rot among all root ages tested (1 to 4 years) when evaluated using a combined scale of disease incidence and severity. Root rot severity was significantly (P < 0.002) enhanced by increasing the inoculum density from 3.45 x 10(2) CFU/g of soil to 1.86 x 10(3) CFU/g of soil. Disease severity was higher at 20 degrees C compared with 15 and 25 degrees C and at -0.02 MPa soil moisture compared with -0.005 and -0.001 MPa. A significant interaction between soil moisture and temperature was observed for root rot severity.

Étude de l'activité antifongique de divers extraits de cannelle

Objective. – This study was undertaken to determine the antifungal activity of cinnamon bark. Material and methods. – Extract from cinnamon with water, hexan, methanol and ethanol were tested on fungi using the method of microtitration assay. Cinnamon was extracted with water, hexan, methanol and ethanol five times and the extracts of each solvent were tested separately for their antimicrobial activity. The minimal inhibitory concentration (MIC) was determined. The extracts were tested on fungal strains using three different techniques; the agar dilution test for the determination of the active extracts, a microtitration method to determine the minimal inhibitory concentration (MIC) of the extracts on growth of yeasts and finally a macrodilution test allowing the evaluation of the extracts on the mycelial mass production by the fungal strains. Results. – The results showed that all the extracts displayed antifungal activity on yeasts. In addition, the determination of the MIC of the active extracts revealed different levels of action. However, the MIC was not influenced by the number of extractions and the fifth extract was as inhibiting as the first one. Finaly, statistical analysis revealed that the hexanic extract was the most active with the MIC varying from 2% (v/v) to 6.2% (v/v), followed by the methanol and water extracts whose the MIC ranged from 2.5% (v/v) to 12.5% (v/v), and the ethanolic extract whose MIC ranged from 5% (v/v) to 12.5% (v/v). Preliminary tests showed that almost all the extracts displayed antifungal activity on moulds. Evaluation of the effects of mycelial production showed that the hexanic extract had the best antifungal effect with a concentration of 10%, and that all 5 extracts were able to totally inhibit the growth of all the species tested. These observations were confirmed by a statistical analysis of variance which revealed that Penicillium cyclopium was the most sensitive mould followed by Aspergillus parasiticus, A. niger and finally A. flavus. Conclusion. – Among the different extracts of cinnamon studied, hexanic extracts were shown to be the most active on the yeasts and moulds tested.

Small heat shock proteins in the development of thermotolerance in Pisolithus sp.

Small heat shock proteins (HSPs) have been shown to confer thermotolerance in many organisms. Here, we demonstrate that small HSPs (sHSPs) can also be involved in development of thermotolerance in Pisolithus sp. In heat shock response, Pisolithus isolate RV82 synthesized proteins of molecular mass 28, 26 and 15–18 kDa. These group of proteins are synthesized when mycelial mass are exposed to heat shock temperature (42 °C) for short period (30 min) and incubated back at 28 °C, the optimal temperature for growth. Our results show sHSPs are an important biochemical alteration in ectomycorrhizal fungi under thermal stress.

Production and use of mutanase from Trichoderma harzianum for effective degradation of streptococcal mutans

Basic cultural parameters affecting mutanase production by Trichoderma harzianum F-340 in shaken flasks and aerated fermenter cultures have been standardized. The best medium for enzyme production was Mandels medium A with initial pH 5.3, supplemented with 0.3% mutan and 0.05% peptone and inoculated with 20% of the 72-h mycelium as inoculum. It was shown that mycelial mass, used in the culture medium as a sole carbon source, induced mutanase synthesis and could be utilized as an inexpensive and easily available substitute for bacterial mutan. Application of optimized medium and cultural conditions enabled us to obtain a high mutanase yield (0.6-0.7 U/mL, 2.0-2.5 U/mg protein) in a short period of time (3-5 days), which was much higher than the best reported in literature. The enzyme in crude state was stable in the pH range of 4.5-6.0, and at temperatures of up to 40oC; its maximum activity was recorded at 45oC and at pH 5.5. The mutanase preparation obtained from the T. harzianum fungus was relatively stable under storage conditions, and showed a high hydrolytic potential in reaction with a mixed-linkage (a-1,3, a-1,6) water-insoluble mutan of streptococcal origin (hydrolysis yield reached a value of 69% in 24 h). Steady-state measurement of the enzymic reaction products during the hydrolysis revealed that mutanase exhibited an exo type of action on mutan. Thin-layer chromatographic analysis showed that glucose was the primary final product of mutan hydrolysis with mutanase. The potential application of mutanase in dentistry is discussed.

Characterization of the specificity of the humoral response to Pythium insidiosum antigens

Pythium insidiosum is the etiological agent of pythiosis, a chronic granulomatous disease affecting people and several animal species, mainly horses. Immunotherapy has recently arisen as a promising therapeutic alternative for the disease. This article reports a preliminary characterization of the specificity of the humoral response to P. insidiosum antigens. The immunodominant P. insidiosum proteins were identified by western immunoblot using sera from naturally infected horses and cattle, and sera from rabbits immunized with mycelial mass antigen (MMA). Sera from naturally infected horses and from immunized rabbits reacted with five main polypeptides of 33.5-, 38-, 39-, 40-, and 80-kDa, respectively. Sera from horses submitted to immunotherapy with MMA showed the same pattern of reactivity. Sera from two naturally infected calves reacted with four main polypeptides: two of them presented a molecular mass of 39- and 40-kDa and were probably the same as those recognized by horse and rabbit sera, whereas the other two (35- and 70-kDa) were exclusively recognized by cattle serum. The initial characterization of P. insidiosum immunodominant antigens may help in understanding the immune response behind the clinical cure obtained through immunotherapy and in designing more effective immunotherapeutic strategies.

Lead and cadmium uptake in the marine fungi Corollospora lacera and Monodictys pelagica

This study provides observations on the effects of lead and cadmium ions on the growth of two species of marine fungi, Corollospora lacera and Monodictys pelagica. On solid media lead appeared to have no effect on the radial rate of growth of fungi. Exposure to increasing cadmium concentrations on solid media resulted in significant reduction ( p < 0.05) in the radial mycelial growth rates of both fungi, especially in M. pelagica. These results reveal significant difference in species sensitivity toward cadmium and, essentially, insensitivity toward lead exposure. In liquid cultures, the metal content of mycelia (metal mass found in mycelium, in mg), and the concentration of metal in dry mycelium (metal mass in 1 g of mycelium, in mg g −1) were both found to increase ( p < 0.05) with the increase in the metal cation concentration, while mycelium dry mass decreased. As it was observed on solid media, cadmium cation affected more severely ( p < 0.05) the growth of M. pelagica in liquid cultures. Ergosterol content of mycelia of C. lacera exposed to increasing cadmium cation concentration decreased, similarly to the trend observed for dry mycelial mass. It was found that ca. 93% of all lead sequestered by C. lacera is located extracellularly. M. pelagica was found to bioaccumulate over 60 mg of cadmium and over 6 mg of lead per 1 g of mycelium, while C. lacera bioaccumulated over 7 mg of cadmium and up to 250 mg of lead per 1 g of mycelium. Overall, the results indicate that both metal ions affect the growth of marine fungi with lead being accumulated extracellularly in the mycelia. Both metals accumulated by fungi may then enter the marine ecosystem food web, of which marine fungi are integral members.

Decay of oak Wood provoked by fungus Stereum hirsutum (Willd. ex Fr.) S. F. Gray. and its' essential physiological requirements

White rot fungi usually decompose cell walls of attacked wood destroying tissue elements (i.e. parenchyma cells, wood fibres, tension wood, tracheas etc) in different amount, depending to wood-species as well as to its' zones. Different fungi secrete specific enzymes that are responsible for certain damages. As consequence, the wood structure use to be significantly and unfixable decomposed and changed. Microscopical analyses that have been run provided clear and indicative information relating to effects of fungal activity on wood tissue. Physiological requirements of fungi are for shore of the highest importance in understanding of mechanism of decaying process in the wood. The most important factors as like temperature and concentration of H ions, as well as main nutrients as sources of carbon, nitrogen and phosphorus can affect the behaviour of wood decaying fungi. The impacts of these factors on the growth and production on mycelial mass of Stereum hirsutum (Willd. ex Fr.) S.F. Gray., have been investigated. This fungus is one of the most frequent appearing on the Sessile- and Pedunculate Oak weakened trees or felled logs, behaving as parasite as well as saprophyte. As a causer of Oak sapwood white rot S. hirsutum causes significant damages of wood at forest- as well as at industrial storages.

Caracterização de Diaporthe citri em diferentes meios de cultura, condições de temperatura e luminosidade

Estudou-se o crescimento micelial de dez isolados de Diaporthe citri, utilizando-se seis meios de cultura (aveia-ágar, maltose-peptona-ágar, batata-dextrose-ágar, folha de laranja-dextrose-ágar, folha de limão-dextrose-ágar, milho-ágar) à temperatura de 22 ± 2 °C e fotoperíodo de 12 h claro/12 h escuro. O cultivo em meio de batata-dextrose-ágar (BDA) foi conduzido em cinco temperaturas diferentes (10, 15, 20, 25 e 30 °C). Três diferentes regimes de luminosidade (12 h claro/12 h escuro, claro contínuo, escuro contínuo) foram utilizados para verificar o crescimento do fungo. Foram observadas variações na produção de picnídios e de massa micelial nos diferentes meios de cultura, temperaturas e regimes de luminosidade testados, sendo que, para a maioria dos isolados, o meio de cultura de aveia-ágar, a faixa de 20 a 25 °C e o regime de claro contínuo induziram maior crescimento micelial. A produção de picnídios foi maior para o regime de luz contínua. O teste de patogenicidade foi feito por inoculação de discos de micélio de 5 mm de diâmetro em ferimentos em ramos e caule de limão 'Feminelo' (Citrus limon) enxertado em citrumelo 'Swingle'(Poncirus trifoliolata x Citrus paradisi) e plantas de limão 'Cravo' (C. limonia) enxertados com laranja 'Valência' (C. sinensis). Após sete dias, houve o aparecimento de exsudação de goma nas plantas inoculadas com os isolados, mas não na testemunha. Todos os isolados mostraram-se patogênicos, sendo os isolados PC2 e PC5, os que causaram comprimento de lesão maior nas plantas.

Characterization, In Vitro Culture, and Molecular Analysis of Thecaphora solani, the Causal Agent of Potato Smut

ABSTRACT The fungus Thecaphora solani (syn.: Angiosorus solani), the causal agent of potato smut, was cultivated in vitro for the first time. Teliospores obtained from galls of infected potato plants were used to inoculate commonly used solid and liquid media. The teliospores produced two kinds of vegetative tissue depending on the nutrient status of the media. A very slow radial-growing, hyaline, and septate mycelium, as usually seen in most of the in vitro-cultivated filamentous fungi, was obtained in wateragar medium after 30 to 40 days. On the other hand, a white, sponge-like mycelial mass was obtained in HCM + 1% activated charcoal, and on common potato dextrose agar or malt-yeast-peptone solid or liquid media, after 40 to 50 days under lab conditions. The identity among teliospores and the sponge-like mycelial mass was corroborated by DNA fingerprinting and partial sequencing of the large subunit (LSU) rDNA region. The sexual cycle of the pathogen was completed under lab conditions based on the development of teliospores on the sponge-like mycelial mass. The first attempt to reproduce the disease under controlled conditions was successful, inducing a gall in a cv. Desirée potato explant cultivated in vitro inoculated with radial-growing mycelia. Phylogenetic analysis of LSU rDNA data of the genus Thecaphora and other smut fungi confirmed the initial classification of the pathogen as T. solani.

Caracterização fisiomorfológica de isolados de Colletotrichum musae

Isolados de Colletotrichum musae obtidos de quatro cultivares de banana (Musa spp.) 'Comprida', 'Maçã', 'Pacovan' e 'Prata' foram estudados quanto ao aspecto morfológico dos conídios, apressórios, características culturais, diâmetro das colônias em meio BDA, germinação dos conídios em água destilada esterilizada e meio líquido BD, como também, quanto ao efeito da combinação de C/N no crescimento micelial, esporulação e peso da matéria seca, sob alternância luminosa, a aproximadamente, 25 ºC. No estudo da relação C/N, as fontes de carbono foram dextrose, sacarose e sorbitol e as de nitrogênio asparagina, peptona e nitrato de potássio combinadas na proporção 10:1 (10 g de carbono para 1 g de nitrogênio). Os resultados mostraram conídios hialinos, com forma e tamanhos característicos da espécie, variando dentro dos limites estabelecidos para a espécie. A relação comprimento/largura foi menor para os isolados Iso-1, Iso-6 e Iso-8 oriundos de banana 'Comprida'. A germinação de conídios ocorreu a partir de 8 h de incubação, havendo diferença significativa entre os isolados, quanto ao percentual de conídios germinados. Foram observados apressórios em todos os isolados, variando em quantidade. Houve diversidade nas características culturais e diâmetro das colônias dos isolados, em BDA. Com relação às combinações C/N, a análise estatística revelou diferença significativa entre os isolados, sob efeito da interação C/N, bem como dos fatores independentes, sobre o crescimento micelial, produção de esporos e peso seco do micélio. De um modo geral, as combinações de carbono com peptona favoreceram esses três processos fisiológicos, porém com diferença significativa entre os isolados de C. musae dentro de cada processo considerado.