Colony Radial Growth Research Articles

Evaluation of combined application of newer insecticides with some fungicides to control groundnut stem rot, Sclerotium rolfsii sacc. under in vitro

An in-vitro experiment was conducted to determine the effect of different insecticides, fungicides and their combination treatments on radial colony growth of Sclerotium rolfsii Sacc. by following poison food technique in PDA medium. Two contact (chlorpyriphos 0.05%, thiodicarb 0.075%), three stomach and contact poison insecticides (chlorfenapyr 0.002%, spinosad 0.0025 and emamectin benzoate 0.003%), among the fungicides one systemic (hexaconazole 0.2%), one contact (Mancozeb 0.25%) and their ten insecticide-fungicide combinations were evaluated with recommended doses against S. rolfsii in laboratory during the year 2009-2010 at S.V. Agricultural College, Tirupati. Chlorpyriphos 0.05 per cent (70.33%) was the best insecticide to restrict the fungal growth effectively followed by emamectin benzoate (34.03%). The two fungicides i.e. mancozeb 0.25 per cent, hexaconazole 0.2 per cent and their combinations with insecticides were found effective in reducing (cent per cent) the growth of S. rolfsii. Fungicides do not shown any antagonism when mixed with insecticides. How to view point the article : Venkatarao, P. and Manjula, K. (2017). Evaluation of combined application of newer insecticides with some fungicides to control groundnut stem rot, Sclerotium rolfsii sacc. under in vitro. Internat. J. Plant Protec., 10(1) : 34-41, DOI : 10.15740/HAS/IJPP/ 10.1/34-41.

New insights into the in vitro development and virulence of Culicinomyces spp. as fungal pathogens of Aedes aegypti

Culicinomyces spp. (Hypocreales: Cordycipitaceae) are facultative fungal pathogens affecting the larval stages from a range of mosquito species and are especially notable in their ability to infect hosts through the digestive tract after conidial ingestion. While Culicinomyces spp. were studied mainly in the 1980s, little is yet known about inter- and intraspecific variability of the in vitro development of these fungi at different temperatures, and nothing is known about the impact of serial host-passage on the development or virulence against Aedes aegypti larvae. The development of ten isolates of C. clavisporus (ARSEF 372, 582, 644, 706, 964, 1260, 2471, 2478, 2479 and 2480) and one of C. bisporalis (ARSEF 1948) was assessed on solid SDAY/4 and liquid SDY/4 at 15, 20, 25, 30 and 35°C. Based on the results of these assays, three isolates were selected (ARSEF 644, 964 and 2479) for three serial host-passage/reisolation cycles, and comparison of the reisolates with the original stock isolates for their virulence, vegetative growth and conidiogenesis. The highest germination rates (≥95%) after 48h incubation were obtained at 25 and 20°C, and the lowest germination (≤12%) at 35°C after the same time. The optimal temperature for radial growth was 25°C (≥11.8mm), followed by 20°C for all isolates. ARSEF 706, 582 and 372 showed the greatest vegetative growth (≥20mm). In general, there was little radial growth of colonies at 30°C (≤2.5mm), and none at 35°C. Isolates, especially ARSEF 964, 2479, and 644, generally produced the highest numbers of conidia at 25°C (≥1.42×105 conidia/plate) after 15days. After two host-passages, conidiogenesis increased significantly on SDAY/4 for ARSEF 2479 but not for ARSEF 644 or 964. All larvae exposed to these three isolates of C. clavisporus died within 7days regardless of the concentration or host-passage; C. bisporalis was not tested in these experiments. The virulence of ARSEF 964 increased at lower concentrations (106–3×105conidia/ml) after the first host-passage.

Testing systemic fungicides for control of Phytophthora oak root disease

SummaryPotassium phosphite (PP) formulations registered as fertilizers are now prohibited in Spain. Therefore, we evaluated the systemic fungicide fosetyl‐aluminium (fos‐al) in comparison with PP, against root rot caused by Phytophthora cinnamomi in Quercus woodlands. The direct effect of both systemic fungicides was evaluated in vitro on P. cinnamomi mycelial growth. Protection of cork and holm oak against infection was also evaluated in planta. Metalaxyl was included in both in vitro and in planta experiments for comparison purposes. At 100 μg/mL, PP totally inhibited colony radial growth, in comparison with 75% achieved by fos‐al. At doses recommended by manufacturers, with fos‐al and metalaxyl applications, root symptoms remained similar to the uninfected control levels. Based on these results, fos‐al is a candidate substitute product for PP in Quercus woodlands for control of Phytophthora oak root disease.

Chinese medicinal plants: an alternative approach for management of Verticillium wilt of cotton

Summary. The use of chemical fungicides is costly and potentially harmful to the environment. The trend towards the environmentally-friendly pesticides has led to the search for new antifungal agents from various sources, including Chinese medicinal herbs. This study aimed to confirm the antifungal potential of selected Chinese medicinal herbs, under in vitro and greenhouse conditions, against Verticillium dahliae , the causal agent of Verticillium wilt of cotton. Preliminary screening of 26 medicinal herbs for antifungal potential showed varied responses, reducing the radial colony growth of V. dahliae , and fungicidal potential. The strongest efficacy was observed for extracts from Prunus mume and Rhus chinensis, followed by Coptis chinensis , Cortex phellodendri chinensis (dried bark of Phellodendron chinense ) and Curcuma longa . The efficacy of the four most effective herbs ( R. chinensis , P. mume, C. chinensis and C. phellodendri chinensis ) under greenhouse conditions correlated with in vitro tests. However, Prunus mume and Rhus chinensis gave the greatest reduction in severity of Verticillium wilt. The greatest improvements in plant height, fresh weight and number of leaves were obtained with P. mume and R. chinensis , followed by C. chinensis and C. phellodendri chinensis . Greatest improvements in plant growth resulted from P. mume and R. chi-nensis . Alternative control with Chinese medicinal herbs showing the greatest antifungal potential could provide economical, safe and non-hazardous tools for management of Verticillium wilt and increased cotton quality from sustainable production.

Application of chitosan and chitosan nanoparticles for the control of Fusarium head blight of wheat (Fusarium graminearum) in vitro and greenhouse

Fusarium head blight (FHB) disease caused by Fusarium graminearum is one of the most important diseases of wheat in humid and warm areas. This disease significantly reduces yield as well as seed quality. The aim of this work was to evaluate the possibility of control of FHB by chitosan (CS) and chitosan nanoparticles (CS/NPs). In vitro, the application of various concentrations of CS and CS/NPs showed significant inhibition of both radial mycelial growth and number of colonies formed against F. graminearum. The application of 1000 and 5000ppm concentration of CS and CS/NPs produced maximum inhibition of radial mycelial growth in comparison to the control, respectively. The microscopic examination, of treated F. graminearum with the CS and CS/NPs, showed dehydration and deformation in mycelial growth and some hyphae were collapsed. The maximum percentage reduction number of colonies was observed in 5000ppm concentration of both CS and CS/NPs. To test the effect of CS and CS/NPs on spore germination, four concentrations were used for 4 and 24h incubation. The 24h incubation of F. graminearum spores with a 5000ppm solution of CS greatly reduced the number of germinating spores. In greenhouse trials, the disease severity percentage was low when CS and CS/NPs were applied before fungus inoculation on the plants and 1000ppm concentration. The spores of F. graminearum germinated on the anther, hyphae penetrated into anther and colonized the palea, lemma and glume after 24 and 72 hpi, respectively. Wherease, the spikelets treated with CS and CS/NPs were infected slowly. Light microscopy and TEM observations indicated that mycelium penetrated into the cells through stoma and transited to other cells by cell wall or plasmodesmata. Mycelial growth caused conidia into cells but CS and CS/NPs prevented of it’s growth. Results showed that CS and CS/NPs could be a useful biological pesticide for controlling FHB.

Biopolymer films to control fusarium dry rot and their application to preserve potato tubers

ABSTRACTFilms were cast using sodium alginate (NaAlg), high molecular weight (HMW) chitosan, and low molecular weight (LMW) chitosan as film forming biopolymers. Fludioxonil (Fl) at 1% concentration was used as fungicide. Thermal stability, mechanical, and water sorption properties of the films were examined. The effects of films on the Fusarium solani colony radial growth were evaluated in vitro and in potato tubers. Results showed that chitosan films were more thermally stable and less hydrophilic than alginate films. Addition of fluodioxonil to the films significantly reduced the film strength and increased the elongation at break as well as the film stiffness. In vitro studies showed that when fludioxonil was added to the formulation, NaAlg and Chitosan‐LMW films had significantly higher antifungal activity (Fungistatic index = 56%) than Chitosan‐HMW films (Fungistatic index = 50%). In vivo studies showed that Chitosan‐LMW‐1%Fl films delay the mycelial growth of F. solani in tubers kept at 25 °C for 2 weeks. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44017.

Cultivation of Aschersonia placenta Berkeley and Broom and its efficacy for controlling Parlatoria ziziphi (Lucas) (Hemiptera: Diaspididae)

The entomopathogenic fungus genus Aschersonia (Deuteromycotina: Hyphomycetes) is host specific to some aleyrodids and scale insects. In search of the Thai endemic species, fungus samples were isolated from cadavers of citrus whiteflies (Aleyrodes tabaci Gennadius) found in citrus orchards in Trat province, Thailand. After morphological analysis and scanning electron microscopic examination, it was identified as Aschersonia placenta Berkeley and Broom. Seven synthetic media, namely: potato dextrose agar (PDA), PDA with pasteurized milk (Foremost®) (PDA + M), Sabouraud dextrose agar with yeast extract (SDAY), SDA with pasteurized milk (Foremost®) (SDA + M), corn meal agar (CMA), water agar with juice of eight vegetable species (V8®) (WA + V8) and WA were explored as appropriate media for fungal cultivation. SDAY and SDA + M gave the best colony radial growth, producing 2.04 ± 0.13 cm and 2.09 ± 0.10 cm in 21 d, respectively. However, based on the ability of A. placenta to produce conidia, PDA and SDAY which produced 2.59 × 108 conidia/mL and 2.69 × 108 conidia/mL, respectively, were considered as the most suitable media for this fungal species. The efficiency assessment of A. placenta for controlling black parlatoria (Parlatoria ziziphi (Lucas)), indicated that a conidial suspension at 1 × 109 conidia/mL gave 23.73% and 27.42% mortality at 14 and 21 d post inoculation, respectively.

Molecular, morphological and pathogenic characterization of six strains of Metarhizium spp. (Deuteromycotina: Hyphomycetes) for the control of Aegorhinus superciliosus (Coleoptera: Curculionidae)

Aegorhinus superciliosus is an important pest on blueberry (Vaccinium corymbosum L.) and other fruit trees. The use of entomopathogenic fungi as Metarhizium spp. has been evaluated for the control of this insect, but variability has been observed among different strains. The aim of this study was to characterize six promising strains of Metarhizium spp. for the control of A. superciliosus. The studied strains were QuM173c, Qu-M363, Qu-M171a, Qu-M156a, Qu-M421, and Qu-M430, all of which belonged to the Chilean Collection of Microbial Genetic Resources (ChCMGR) of the Instituto de Investigaciones Agropecuarias (INIA), Chile. Molecular characterization was made by sequencing the ITS region (Internal Transcribed Spacers, ITS-5.8S rDNA). The morphology of conidia was evaluated through scanning electron microscopy and radial colony growth was evaluated in potato dextrose agar (PDA), Sabouraud dextrose agar (SDA), agar enriched with larvae of Galleria mellonella (Lepidoptera: Pyralidae) (GA), and agar enriched with adults of A. superciliosus (AA). Pathogenicity was studied based on mortality of adults of A. superciliosus inoculated with conidia. Sequencing of the ITS-5.8S rDNA region indicates that the strains belong to the clade of M. anisopliae var. anisopliae, except for Qu-M171a, which was identified as M. anisopliae var. lepidiotum. Conidia average length for the six strains was 5.09 µm and average conidia width was 1.92 µm. Radial colony growth differences were observed between strains (p < 0.01) and between different growth media (p < 0.01). The strains exhibited the highest colony growth in the GA medium, while in the AA medium they showed the lowest (p < 0.01). Pathogenicity tests show that Qu-M430 reached a 90% mortality rate (p < 0.01). Results show that there is variability between the studied strains, which is expressed in their morphology, molecular characteristics and pathogenicity towards A. superciliosus.

Potato root infection by Rhizoctonia solani anastomosis group-3 and Colletotrichum coccodes under current and future spring weather in northern Italy

SUMMARYA study was performed in controlled conditions to reproduce cold and warm spring regimes in the east Po valley, northern Italy with a temperate subcontinental climate, to evaluate whether and to what extent spring weather regimes favour the attack of Rhizoctonia solani or Colletotrichum coccodes on potato, in view of predicted climate change. The main experiment, preceded by a controlled chamber set of tests to quantify response to temperatures of R. solani anastomosis group (AG)-3 and C. coccodes strains, showed that limit temperatures (minimum, maximum and optimum of colony radial growth) of R. solani AG-3 are 6 °C lower than those of C. coccodes. Then, a trial to reproduce early growth stages of potato was performed in phytotrons with sprouts of cvar Hermes to simulate cold and warm spring regimes with two different relative soil moisture contents. That simulation was carried out on native non-sterilized soil samples which were co-inoculated artificially with R. solani AG-3 and C. coccodes. Species-abundance findings of fungal root colonization in potato roots and molecular quantification (quantitative polymerase chain reaction) of C. coccodes and R. solani AG-3 inoculum growth in soil showed that: (i) C. coccodes is more competitive than R. solani AG-3 in colonizing potato root both in warm and cold spring regimes; (ii) R. solani AG-3 infected potato roots only in the coldest spring regimes regardless of soil moisture content; (iii) soil temperature is the greatest factor that influences root colonization of C. coccodes and R. solani as well as that of soil inhabiting fungi including some potential antagonists; (iv) R. solani AG-3 and C. coccodes seem to greatly increase in soil under the relative driest and warmest spring weather regimes expected according to the mean scenarios of climate changing in northern Italy; (v) binucleate Rhizoctonia AG-A, a common non-pathogenic fungus indigenous to agricultural soil of that area, appears to be antagonistic towards root fungal pathogens of potato.

Mycoflora associated with Paanch Phoron and its management by common salt

Abstract not availableBangladesh J. Sci. Res. 28(1): 79-83, June-2015

Comparative Evaluation of Different Fungicides Against Sheath Blight of RiceIn Vitro

The present investigation was conducted to test the efficacy of different fungicides against sheath blight of rice caused by Rhizoctonia solani Kuhn viz. Nativo 75WG, Contaf 5EC, Spencer 24EC, Sheathmar 3L, Monceren 250EC, Tilt 25EC and Bavistin 50WP. The PDA medium amended with concentrations of 1,5,10, 20, 30, 50, 100, 200 μg/ml (a.i. basis) of fungicide was poured in sterilized petriplates under aseptic conditions. Five petriplates (five replications) were used for each concentration to measure the radial colony (mycelial) growth of R.solani. All the fungicides were found to be effective under in vitro condition. Nativo 75WG was found to be most effective fungicide showing 100% growth inhibition in concentrations above 10ppm whereas Sheathmar 3L and Spencer 24EC were found to be least effective.

Toxigenic potentiality of Aspergillus flavus and Aspergillus parasiticus strains isolated from black pepper assessed by an LC-MS/MS based multi-mycotoxin method

A liquid chromatography triple quadrupole tandem mass spectrometry method was developed and validated to determine mycotoxins, produced by fungal isolates grown on malt extract agar (MEA). All twenty metabolites produced by different fungal species were extracted using acetonitrile/1% formic acid. The developed method was applied to assess the toxigenic potentiality of Aspergillus flavus (n = 11) and Aspergillus parasiticus (n = 6) strains isolated from black peppers (Piper nigrum L.) following their growth at 22, 30 and 37 °C. Highest mean radial colony growth rates were observed at 30 °C for A. flavus (5.21 ± 0.68 mm/day) and A. parasiticus (4.97 ± 0.33 mm/day). All of the A. flavus isolates produced aflatoxin B1 and O-methyl sterigmatocystin (OMST) while 91% produced aflatoxin B2 (AFB2) and 82% of them produced sterigmatocystin (STERIG) at 30 °C. Except one, all the A. parasiticus isolates produced all the four aflatoxins, STERIG and OMST at 30 °C. Remarkably high AFB1 was produced by some A. flavus isolates at 22 °C (max 16–40 mg/kg). Production of mycotoxins followed a different trend than that of growth rate of both species. Notable correlations were found between different secondary metabolites of both species; R2 0.87 between AFB1 and AFB2 production. Occurrence of OMST could be used as a predictor for AFB1 production.

Effects of Three Volatile Oxylipins on Colony Development in Two Species of Fungi and on Drosophila Larval Metamorphosis.

The aim of this study is to investigate the effects of three volatile oxylipins on colony development in two fungi and on Drosophila larval metamorphosis. Using an airborne exposure technique, three common and volatile oxylipins (1-octen-3-ol, (E)-2-hexenal, and 1-hexanol) were compared for their effects on spore germination and colony growth in Aspergillus niger and Penicillium chrysogenum, as well as for their effects on the morphogenesis of larvae of Drosophila melanogaster. Conidia of both A. niger and P. chrysogenum plated in the presence of low concentrations (50ppm) of these three volatile organic compounds (VOCs) formed fewer colony-forming units (CFUs) and exhibited reduced radial growth of colonies as compared to controls. When A. niger and P. chrysogenum spores were germinated in the presence of the enantiomers of 1-octen-3-ol, (R)-(-)-1-octen-3-ol had the greatest impact on colony morphology (decreased sporulation and colony diameter), while (S)-(+)-1-octen-3-ol and the racemic form yielded similar morphological changes but to a lesser extent. In addition, Drosophila larvae exposed to vapors of these oxylipins exhibited serious delays in metamorphosis and toxic effects on pupae and adult stages. Low concentration of these three VOCs can significantly inhibit the formation of CFUs and the growth of fungi. (R)-(-)-1-octen-3-ol imposed the greatest impact on fungal morphology compared to (S)-(+)-1-octen-3-ol and the racemic form. The three volatile oxylipins could also delay the metamorphosis of Drosophila and impose toxic effects on its pupae and adult stages.

Effect of Tricyclazole on morphology, virulence and enzymatic alterations in pathogenic fungi Bipolaris sorokiniana for management of spot blotch disease in barley.

Bipolaris sorokiniana synthesizes the 1,8-dihydroxynaphthalene (DHN) melanin via pentaketide pathway and promotes the development of aerial mycelia and conidia. A melanin biosynthesis inhibitor Tricyclazole (TCZ), brought changes when applied at 5-100μgml(-1) concentration in the colony morphology, radial growth, mycelia weight, melanin content, antioxidant enzymes (SOD and CAT) and extracellular hydrolytic enzymes (cellulase, pectinase, amylase and protease) in black, mixed and white isolates of B. sorokiniana. A significant alteration was recorded in antioxidant enzymes in black and mixed isolates; however, non-significant alteration was recorded in white isolate. Isolates of B. sorokiniana exposed to 100µgml(-1) TCZ showed significantly increased formation of superoxide radical (O 2 (·-) ) and hydrogen peroxide (H2O2)·H2O2 was detected significantly high in hyphae and conidia while, O 2 (·-) was found primarily in the conidia. Microscopic results suggest that TCZ damages not only the cell wall but also the cell membrane. The foliar application of TCZ (25, 50 and 100µgml(-1)) decreases the area under disease progress curve, lesion development and spore formation on barley leaves thereby reducing potential for the disease development. In conclusion TCZ influences the pathogenic ability by damaging the cell structure of hyphae and conidia and also alters the antioxidant enzyme levels in B. sorokiniana. TCZ may therefore,works against to pathogen for better management of spot blotch disease in barley infected with B. sorokiniana.

English

An experiment was carried out to find the variability among twenty sclerotial isolates of Rhizoctonia solani collected from potato growing areas of Gilgit-Baltistan. These isolates were grown in different culture media, mycelial compatibility and fungus protein profile were investigated. Culture media were used to study radial colony growth and sclerotial production of isolates. Radial colony growth (RCG) and sclerotial production (SP) of isolates against culture media ranged from 12.31-21.55; 3.66-22.66 in potato dextrose agar, 12.67-18.56; 4.66-10.66 in czpedox agar, 12.02-20.42; 2.00-8.66 in corn meal agar and 10.54-14.16; 0.00-3.00 in water agar, respectively. These isolates were further classified into three categories on the basis of RCG and SP. Result revealed that out of total isolates, 60% showed medium RCG and 40% fast growth, while 10, 60 and 30% isolates showed low, medium and high SP. Furthermore, sclerotial characteristic such as size, shape and distribution pattern were also recorded. Mycelial compatibility and incompatibility among the R. solani isolates was also studied. The results indicated that out of 190 combinations, 72.10% were compatible, whereas 27.90% were incompatible. Fungus protein profile of twenty isolates of R. solani by sodium dodecyl suplphate gel electrophoresis (SDS-PAGE) recovered sixty one bands with different frequencies among the isolates. Cluster analysis of twenty isolates divided them into two major lineage groups, A and B. Lineage A contained 65% isolates whereas lineage B contained 35% isolates. These lineages were further divided into thirteen clusters (C1-C13); A was comprised of eight and B five clusters, respectively. Key words: Rhizoctonia solani, sclerotial isolates, radial colony growth, sclerotial feature, mycelial compatibility, sodium dodecyl suplphate gel electrophoresis (SDS-PAGE), Gilgit-Baltistan.

English

The production of cellulase by the yellowish orange sclerotia producing species, Aspergillus melleus UPAR01 on lignocellulosic material by solid state fermentation (SSF) was investigated. The first experiment was conducted to find out the colony radial growth rate (Kr) of fungus on solid medium using potato dextrose agar (PDA) and incubated at 30&deg;C in the dark. The result shows that the average Kr value of A. mellues strain approximately was 0.77&plusmn;0.03 cm/day. When the fungus was used to produce cellulase using maize crop residues as the sole carbon source by SSF at 30&deg;C for seven day, the values of FPase, endoglucanase, b-glucosidase, and xylanase were achieved at 0.284&plusmn;0.04, 9.45&plusmn;0.33, 1.20&plusmn;0.12, 12.58&plusmn;0.08 U/mg protein, respectively. The optimal pH and temperature (&deg;C) for the enzymatic activities was expressed by response surface methodology (RSM). The data shows that the optimum pH range was between 5.5 and 5.8 and the optimum temperature ranged from 53 to 59&deg;C. In addition, none of the metal ions and ethylene-diaminetetra-acetic acid (EDTA) induced cellulase and xylanase activities.&nbsp; Key words: Aspergillus melleus, cellulase, solid state fermentation (SSF), maize crop residues.

Transcriptomic profiles of Aspergillus flavus CA42, a strain that produces small sclerotia, by decanal treatment and after recovery

Aspergillus flavus is a ubiquitous saprophyte and is capable of producing many secondary metabolites including the carcinogenic aflatoxins. The A. flavus population that produces small sclerotia (S strain) has been implicated as the culprit for persistent aflatoxin contamination in field crops. We investigated how the plant volatile decanal, a C10 fatty aldehyde, affected the growth and development of the S strain A. flavus. Decanal treatment yielded fluffy variants lacking sclerotia and conidia and exhibiting a dosage-dependent radial colony growth. We used RNA-Seq analysis to examine transcriptomic changes caused by decanal and after removal of decanal. Mature sclerotia contained only 80% of the total transcripts detected in all samples in comparison to 94% for the decanal treated culture. Gene ontology (GO) analysis showed that decanal treatment increased expression of genes involved in oxidoreductase activity, cellular carbohydrate metabolism, alcohol metabolism and aflatoxin biosynthesis. The treatment affected cellular components associated with cell wall, and gene expression of glucanases, α-amylases, pectinesterase and peptidase required for its biosynthesis was increased. After decanal was removed, the culture resumed sclerotial production. Moreover, its GO terms significantly overlapped with those of the untreated culture; five of the enriched molecular functions, oxidoreductase activity, monooxygenase activity, electron carrier activity, heme binding, and iron binding were found in the untreated culture. The GO term of cellular component enriched was mainly integral protein constituents of the membrane. The results suggested that decanal halted development at the vegetative state rendering the fungus unable to produce conidia and sclerotia. The induced fluffy phenotype could be related to lower transcript abundance of flbB, flbD, and flbE but not to veA expression. Increased abundance of the laeA transcript in the treated culture correlated with early transcriptional activation of aflatoxin and kojic acid biosynthesis gene clusters. Expression profiles revealed subtle differences in timing of activation of the respective 55 secondary metabolite gene clusters.

Prevalence, persistence, and phenotypic variation of Aspergillus fumigatus in the outdoor environment in Manchester, UK, over a 2-year period

Aspergillus fumigatus, an opportunistic fungal pathogen that causes invasive aspergillosis in immunosuppressed patients, is considered to be the world's most dangerous mould. It is widely distributed in the environment, and airborne asexual conidia serve as the main mode of transport for pulmonary lung infection. It is important to monitor seasonal airborne conidia levels when assessing the risk of acquiring this infection. In this study, air was sampled for total viable fungal spores and viable A. fumigatus conidia monthly over a 2-year period (2009 and 2010) close to Manchester, UK, city center. Total viable airborne fungal counts varied seasonally, peaking in the summer and autumn for both years and reaching levels of approximately 1100-1400 colony-forming units (CFU)/m(3); counts were strongly positively correlated to mean temperature (R(2) = 0.697). By contrast, A. fumigatus viable airborne counts were not seasonally associated; persistent low levels were between 3 and 20 CFU/m(3) and were not correlated with mean temperature (R(2) = 0.018). A total of 220 isolates of A. fumigatus were recovered on potato dextrose agar (PDA) at 45°C, and internal transcribed spacer sequencing and restriction digestion of a partial polymerase chain reaction amplicon of the β-tubulin gene (benA) of 34 randomly selected isolates were used to confirm the isolates as A. fumigatus. When the colony radial growth rates (Kr) were determined, the highest rates were observed on PDA, followed by Vogel's medium supplemented with phosphatidylcholine and Vogel's medium alone. Clinical isolates had a significantly higher mean colony Kr on PDA compared with environmental isolates.

The putative stress sensor protein MtlA is required for conidia formation, cell wall stress tolerance, and cell wall integrity in Aspergillus nidulans.

The Mid2-like protein MtlA is a putative sensor of the cell wall integrity (CWI) signaling pathway in Aspergillus nidulans. An MtlA-EGFP fusion protein was localized at the cell surface and septa. The mtlA disruptant (∆mtlA) showed radial colony growth similar to the wild-type (wt) strain, but showed reduced conidia formation. The ∆mtlA mutant showed growth deficiency in the presence of inhibitors of cell wall synthesis. Moreover, mtlA disruption resulted in a reduction in the glucan and chitin content in the cell wall. These results suggest that MtlA plays a significant role in asexual sporulation, cell wall stress tolerance, and the maintenance of CWI in A. nidulans, but transcriptional upregulation of α-1,3-glucan synthase gene agsB induced by micafungin was observed in the ∆mtlA strain as well as the wt strain. Thus, MtlA is not essential for activation of the downstream CWI signaling pathway components identified in previous studies of Saccharomyces cerevisiae.

Utilizing Soybean Milk to Culture Soybean Pathogens

Liquid and semi-solid culture media are used to maintain and proliferate bacteria, fungi, and Oomycetes for research in microbiology and plant pathology. In this study, a comparison was made between soybean milk medium, also referred to as soymilk, and media traditionally used for culturing soybean pathogens to determine if soymilk medium was an effective medium for growth of Colletotrichum truncatum, Fusarium virguliforme, Macrophomina phaseolina, Passalora sojina, Phomopsis longicolla, Phytophthora sojae, Pythium irregulare, Rhizoctonia solani, and Sclerotinia sclerotiorum. Based on radial mycelial colony growth rates, C. sojina grew significantly (P C. truncatum and F. virguliforme grew significantly (P P S. sclerotiorum grown on SDA as compared to PDA. Soymilk used with agar or used alone as a broth may be an option for replacing more expensive processed culture media.