Pathogenic and non-pathogenic mycoflora in the air and phylloplane ofTriticum aestivum L

Aerobiological investigations were carried out over wheat (Triticum aestivum L.) fields near Barrackpore, West Bengal, India for two consecutive crop seasons. In 1990–91, except for the very seedling stage there was a more or less uniform spore count up to the maximum vegetative growth stage and from flowering onwards, a gradual increase in total cfus was observed with the peak (331 CFUs) during the harvesting stage. In the second season, similar results were recorded where peak spore load (2064 CFUs) in the air was during harvesting operation followed by a sudden decline in the empty field.Cladosporium spp. dominated both the seasons mainly up to February.Penicillium, Curvularia, Aspergillus andCephalosporium were the most frequent non-pathogenic fungal types. Among the pathogenic fungi,Alternaria andDrechslera were recorded to be the most virulent to wheat crop, after inflorescence to later stages in both the seasons causing heavy leaf damage producing necrotic spots during which peak cfus were found.Fusarium was frequently found showing the peak during vegetative growth period.Sclerotium was more common in the second season than in the first season. High occurrence ofNigrospora was recorded in the earlier stages. Sterile forms were found regularly. The phylloplane studies revealed thatCladosporium was the most dominant flora contributing 40–66% up to February in winter; gradually disappeared from the leaf surface with the onset of summer.Aspergillus andPenicillium showed the reverse picture. WhileCurvularia was isolated in high amount during later stages;Nigrospora mainly during the vegetative growth stages.Alternaria (caused Alternaria blight) andDrechslera were significantly isolated during harvesting (28.08%) and at late grain maturation stage (80.10%), respectively.Sclerotium and Sterile forms were recorded regularly unlikeFusarium andHelminthosporium.     

Pathogenic and non-pathogenic mycoflora in the air and phylloplane ofTriticum aestivum L.

Aerobiological investigations were carried out over wheat (Triticum aestivum L.) fields near Barrackpore, West Bengal, India for two consecutive crop seasons. In 1990–91, except for the very seedling stage there was a more or less uniform spore count up to the maximum vegetative growth state and from flowering onwards, a gradual increase in total cfus was observed with the peak (331 CFUs) during the harvesting stage. In the second season, similar results were recorded where peak spore load (2064 CFUs) in the air was during harvesting operation followed by a sudden decline in the empty field.Cladosporium spp. dominated both the seasons mainly up to February.Penicillium, Curvularia, Aspergillus andCephalosporium were the most frequent non-pathogenic fungal types. Among the pathogenic fungi,Alternaria andDrechslera were recorded to be the most virulent to wheat crop, after inflorescence to later stages in both the seasons causing heavy leaf damage producing necrotic spots during which peak cfus were found.Fusarium was frequently found showing the peak during vegetative growth period.Sclerotium was more common in the second season than in the first season. High occurrence ofnigrospora was recorded in the earlier stages. Sterile forms' were found regularly. The phylloplane studies revealed thatCladosporium was the most dominant flora contributing 40–66% up to February in winter; gradually disappeared from the leaf surface with the onset of summer.Aspergillus andPenicillium showed the reverse picture. WhileCurvularia was isolated in high amount during later stages;Nigrospora mainly during the vegetative growth stages.Alternaria (caused Alternaria blight) andDrechslera were significantly isolated during harvesting (28.08%)and at late ‘grain maturation’ stage (80.10%), respectively.Sclerotium and ‘Sterile forms’ were recorded regularly unlikeFusarium andHelminthosporium.     

Estimation of aeromycoflora in jute fields

An air survey of jute fields for two seasons in West Bengal, India, revealed that the total colony forming units (CFUs) varied with time, showing peaks (231 and 483 CFUs, respectively) during harvesting of the crop. The effect of temperature as well as relative humidity is probably not so significant. However, the total rainfall does count. The CFUs are inversely proportional to the total rainfall. In the survey conducted, it was found that the rainfall of 1346.3 mm and 947.1 mm, during the two seasons corresponded to 574 and 1002 CFUs respectively, irrespective of growth phases of the crop. Penicillium and Aspergillus were the most dominant saprophytes followed by Curvularia and Cladosporium in the first season, while in 1991 Aspergillus and Curvularia were the most dominant, followed by Cephlalosporium, Penicillium and Cladosporium, along with Pullularia in the mid season. Pathogenic Macrophomina phaseolina causing stem rot disease, although appeared irregularly in the first season, became more frequent in later stages in the second season. Amongst other pathogens Helminthosporium occurred twice and three times in the earlier part of the two crop season, while Alternaria, Nigrospora and Fusarium occurred very occasionally.     

Fungi of certain stored vegetable seeds in relation to pre- and post-emergence effects

A number of fungi were found associated with stored cauliflower, common bean, and pea seeds, but onlyHelminthosporium sp. on cauliflower,Fusarium sp. on common bean, andAlternaria sp. on pea were proved pathogenic. Artificial inoculation tests withHelminthosporium sp.,Fusarium sp., andAlternaria sp. resulted in 30, 16.6, and 26.6 % pre-emergence injuries to cauliflower, common bean, and pea respectively. Also, these fungi were responsible for considerable post-emergence mortality of seedlings.

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Zusammenfassung Eine Anzahl von Pilzen sind mit dem Samen von Karfiol, Bohnen und Erbsen vergesellschaftet gefunden worden.Helminthosporium sp. nur an Karfiol,Fusarium sp. nur an Bohnen undAlternaria sp. nur an Erbsen haben sich als pathogen erwiesen. Küristliche Einimpfung mitHelminthosporium sp.,Fusarium sp., undAlternaria sp. gab positive Resultate in 30, 16.6, und 26.6 % bezw. in Karfiol, Bohnen und Erbsen. Diese Pilzen waren auch für das Absterben junger Pflanzen verantwortlich.

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Portion of a thesis submitted by the senior author to the Agra University, Agra, India, in partial fulfilment of the requirements for the degree of M.Sc. (Ag.).     

Airspora Measured in a Paddy Field in West Bengal,India

Aeromycoflora studies above an “Aman” variety of paddy (Oryza saliva L.) were carried out for two consecutive seasons, in 1990 and 1991, in the vicinity of Barrackpore, West Bengal, by means of the culture plate exposure technique. A more or less uniform spore concentration was observed during the early part of the vegetative stages in 1990 with an abrupt increase and peak during the maximum vegetative growth period. In 1991, a uniform spore count was found up until the flowering stages. A gradual increase in spore count after flowering was recorded in both seasons with the highest peaks during harvesting, followed by a sudden decrease after the harvest. The dominant genera isolated were Aspergillus, Currularia, Cladosporium and Penicillium. Aspergillus appeared in high concentrations from the very beginning of the crop season up to the flowering stages, with a gradual fall after flowering, while Cladosporium showed the reverse pattern. Currularia and Penicillium occurred regularly throughout the crop season.

Phytopathogenic types were represented by Helminthosporium oryzae, Fusarium, Altemaria and Nigrospora. Helminthosporium oryzae appeared in the air when the plants attained appreciable vegetative growth, being seen as “brown spots” on the foliage, and reaching peak concentration during harvesting. Fusarium in contrast to Altemaria appeared regularly in the air except during the later part of vegetative growth. Nigrospora was recorded only occasionally. A considerable number of “Sterile Forms” were present throughout both seasons.     

Aeromycoflora in the Central Milk Dairy of Calcutta, India

Intramural aeromycological survey was performed at the Central Milk Dairy, Calcutta, covering eight locations within the Dairyusing Burkard personal volumetric air sampler. The locations were butter cold storage (−2 °C), cold store (8 °C), packaging section (23 °C), milk processing section (24 °C), reconstituent of skimmed milk (24 °C), quality control lab (25 °C), raw milk reception (28 °C) and loading dock (26 °C). A number of fungal spores, conidia and mycelia were recorded in different rooms: the highest spore quantity was recorded in the packaging section (23 °C) and the minimum at the butter cold store (−2 °C). The dominant spores consisted of Aspergillus niger, A flavus,Cladosporium sp., Fusarium sp., Curvularia sp.,Alternaria sp., Torula sp., Myrotheciumsp., Helminthosporium sp., Periconia sp.,Nigrospora sp. and Pithomyces sp. This revised version was published online in June 2006 with corrections to the Cover Date.     

Quantification of Alternaria,Cladosporium, Fusarium and Penicillium verrucosum in Conventional and Organic Grains by qPCR

We analysed the levels of Alternaria, Cladosporium, Fusarium and Penicillium verrucosum in grain samples harvested in 2011 and 2012 from conventional and organic farms using qPCR. In general, both Alternaria and Cladosporium occurred in all cereal grains in the highest quantities, followed by P. verrucosum and Fusarium. Alternaria, Cladosporium and P. verrucosum had the highest levels in crop mixtures, barley and rye and lower levels in wheat, while Fusarium levels were the highest in crop mixtures and wheat. The levels of Alternaria and P. verrucosum were higher in organic rye and wheat than conventional grains. Although the level of Fusarium was higher in conventional than organic rye, opposite results were obtained for crop mixtures. A positive correlation was found between Alternaria, Cladosporium and P. verrucosum, indicating that similar factors might affect the distribution of these fungi in grains.     

Airborne pollen and fungal spores in Garki,Abuja (North-Central Nigeria)

The ambient atmosphere is dominated with pollen and spores, which trigger allergic reactions and diseases and impact negatively on human health. A survey of pollen and fungal spores constituents of the atmosphere of Garki, Abuja (North-Central Nigeria) was carried out for 1 year (June 1, 2011–May 31, 2012). The aim of the study was to determine the prevalence and abundance of pollen and fungal spores in the atmosphere and their relationship with meteorological parameters. Airborne samples were trapped using modified Tauber-like pollen trap, and the recipient solutions were subjected to acetolysis. Results revealed the abundance of fungal spores, pollen, fern spores, algal cysts and diatoms in decreasing order of dominance. The atmosphere was qualitatively and quantitatively dominated by pollen during the period of late rainy/harmattan season than the rainy season. Numerous fungal spores were trapped throughout the sampling periods among which Alternaria spp., Fusarium spp., Cladosporium spp. and Curvularia spp. dominated. These fungi have been implicated in allergic diseases and are dermatophytic, causing diverse skin diseases. Other pathogenic fungi found in the studied aeroflora were Dreschlera spp., Helminthosporium spp., Torula spp., Pithomyces spp., Tetraploa spp., Nigrospora ssp., Spadicoides spp., Puccinia spp. and Erysiphe graminis. Total pollen and fungal spores counts do not show significant correlation with meteorological parameters.     

Isolation,characterization, and bioactivity of endophytic fungi of <Emphasis Type="Italic">Tylophora indica</Emphasis>

Dothediomycetes sp., Alternaria tenuissima, Thielavia subthermophila, Alternaria sp., Nigrospora oryzae, Colletotrichum truncatum, and Chaetomium sp. were isolated as endophytic fungi from leaves and stems of the medicinal plant, Tylophora indica, based on rDNA sequencing of ITS region and microscopic examination. Alternaria tenuissima, Colletotrichum truncatum, and Alternaria sp. were found to be active against both Sclerotinia sclerotiorum and Fusarium oxysporum. Chaetomium sp. showed very mild activity against Sclerotinia sclerotiorum and Fusarium oxysporum. Whereas Dothideomycete sp. and Thielavia subthermophila showed high activity against Sclerotinia sclerotiorum. Methanol extract of Dothediomycetes sp. showed 66.5% growth inhibition (GI) at 500 μg/ml.     

Microflora of stored grain in international trade

Although the temperature of grain in the holds of ships arriving in Japan from Argentina, Australia, Canada, China and USA during 1966–67 varied with the grain, country of origin, and season, it was likely to be determined by the temperature of the grain when it was loaded into the ships. Dockage level varied among bulks of the same type of grain, but the mean dockage in any one crop was always larger when originating from the USA than from other countries. Generally the viability of the grain was good, but when it was reduced, interaction of variety and time seemed to be the principal cause. Field fungi — non-pathogenic Alternaria, and the pathogenic Helminthosporium and Fusarium species — tended to die out, during transport, thus reducing the hazards of new pathogenic strains being distributed across international boundaries. The non-pathogenic field fungi, Cladosporium and Phaeoramularia, were persistent. Although common in grain shipments from all countries, species of Aspergillus and Penicillium varied quantitatively with the different grains. In this respect, more Aspergillus spp. were found in grains originating in the USA and Australia than those originating in Canada. The primary contamination by storage fungi appeared to be at the source, at or after harvest and in storage prior to export.     

Effects of weather conditions on selected airborne fungal spores in the southern part of the state of Enugu,Nigeria

A study of airborne fungal spore was carried out at nine locations in the southern part of the state of Enugu, Nigeria, from March 2005 to February 2006. The aim of the study was to ascertain the variations in selected fungal spore types at the sites owing to weather conditions. The variation in airborne fungal spores of 14 taxa was studied using modified Tauber pollen traps including Alternaria, Corynespora, Curvularia, Drechslera type, Endophragmiella, Botryodiplodia, Ganoderma, Gliomastrix, Nigrospora, Pithomyces, Spegazzinia, Sporidesmium, Tetraploa and Ustilago. The frequency of the spore types recorded showed considerable variation. The highest spore counts were recorded in July, June and October. The highest numbers of fungal spores were recorded during the rainy season (June–October) to early dry season (November–December). The peak of occurrence of most selected fungal spore types was July. The highest percentages of fungal spores were documented at the recording stations Mgbowo Junction, UNTH Ituku Ozalla and Oji River Express Junction. Spearman’s correlation analyses were performed for the monthly amounts of the fungal spore types and monthly meteorological factors. The numbers of Curvularia, Nigrospora and Sporidesmium was significantly correlated with relative humidity, while those of Endophragmiella, Pithomyces and Nigrospora were significantly correlated with temperature. A significant correlation was also found between the number of Nigrospora spores and light intensity and Sporidesmium spores and wind velocity. Relative humidity and temperature seem to be the most important weather conditions affecting the frequency of the selected spore types in the atmosphere.     

The effects of recent changes in air temperature on trends in airborne <Emphasis Type="Italic">Alternaria</Emphasis>, <Emphasis Type="Italic">Epicoccum</Emphasis> and <Emphasis Type="Italic">Stemphylium</Emphasis> spore seasons in Bratislava (Slovakia)

Over the period 2002–2014, air temperature significantly increased regionally for Bratislava. However, no significant shifts have been observed in other meteorological parameters examined. The aim of this study was to analyse the effect of significant temperature trends on timing, duration and intensity of Alternaria, Epicoccum and Stemphylium spore seasons. Aerobiological monitoring was conducted using a Burkard 7-day volumetric spore trap. Mann–Kendall tau test was used to determine trends in spore seasons characteristics, whereas Spearman’s correlation coefficients were calculated to establish the relationships between temperature and spore season time series. Spore seasons of analysed taxa changed throughout the years of study. Alternaria spore season now starts earlier, ends later and lasts longer. Start, end and peak dates as well as duration of Alternaria spore seasons were significantly correlated with recorded increases in winter temperatures. Despite significant lengthening of Alternaria spore seasons, the lack of rising trend in its spore season index has been registered. This phenomenon could be partly explained by the reduction in the source vegetation due to drop of agricultural land use areas in Bratislava. In contrast, the intensity of Stemphylium spore seasons significantly increased during the study period and was correlated with recorded increases in summer–autumn temperatures. Based on the results of this study, it could be concluded that changes in selected fungal spore season patterns in Bratislava (earlier start date, later end date and longer duration of Alternaria spore seasons and higher Stemphylium spore season indexes) might be caused by the recorded local change in air temperature.     

Molecular heterogeneity in the 18s DNA gene of Alternaria sp. and Fusarium sp. producing mycotoxins in rice and maize grains

Background

Food contaminated with fungi and their toxins is a problem that threatens many developing countries. Kingdom of Saudi Arabia depends on the exported grain and legume seeds.

Characterization of fungi transferred by dust storms in Kuwait and their plant pathogenicity

Dust storms carry large amounts of plant detritus and microorganisms that may cause diseases in humans, animals or plants. These storms are frequent in Kuwait throughout the year. This research was conducted to identify the fungal species carried by the dust storms in Kuwait, originating from the northwesterly direction, with emphasis on plant pathogens. Fungi were isolated from settled dust samples and identified using established microbiological and molecular approaches. Fungal isolates identified as Fusarium oxysporum from settled dust were examined for pathogenicity using a number of crop plants. In total, 17 genera of fungi were identified in the dust samples. These fungi included plant pathogens or facultative plant parasites that were transported in the dust storms as viable propagules. The most common dust-carried fungi belonged to the genera Fusarium, Alternaria, Ulocladium, Phoma, Aspergillus, Acremonium and Penicillium. The F. oxysporum isolates that had been characterized by partial 18S rRNA gene sequencing were pathogenic, causing root and stem rot in tomato, bean and cucumber, but not squash.     

Endophytic fungi of teak leaves Tectona grandis L. and rain tree leaves Samanea saman Merr.

Summary In order to study the foliar endophytes from teak (Tectona grandis L.) and rain tree (Samanea saman Merr.) growing in the campus of Chulalongkorn University, healthy leaves were collected at two-monthly intervals during January to December. The number of genera and species, together with their colonization frequency (CF%) in mature teak and rain tree leaves were greater than those in the young leaves. More endophytic isolates in the leaves of both trees were recovered during the rainy season. The fungal genera found in both young and mature teak leaves were Alternaria, Colletotrichum, Nigrospora, Phomopsis and mycelia sterilia. Phomopsis was the dominant genus in both young (newly emerged) and mature leaves. Fusarium, Penicillium, Schizophyllum commune and members of the Xylariaceae were found only in mature leaves. For the rain tree leaves, species of Phomopsis and mycelia sterilia were found in both young newly emerged and mature leaves. Colletotrichum and Penicillium were found only in mature leaves, whereas Nigrospora was found only in young newly emerged leaves. In this study, Phomopsis was the dominant genus in the leaves of both tree species. A total of 37 isolates of endophytic fungi isolated from teak and rain tree leaves were tested for the production of antimicrobial activities. Out of these, 18 isolates could produce inhibitory substances effective against Bacillus subtilis, Staphylococcus aureus and Escherichia coli and 3 isolates inhibited growth of Candida albicans in vitro.     

First volumetric record of fungal spores in the atmosphere of Montevideo City,Uruguay: a 2-year survey

In Uruguay, aeromycological studies are restricted to a gravimetric analysis performed from December 1942 to March 1944 in Montevideo where spores of Pucciniaceae, Alternaria and Helminthosporium were the only specimens identified. Daily monitoring of airborne fungal spores was carried out for the first time in Montevideo, from April 2012 to March 2014, using a Rotorod sampler in order to evaluate the seasonal variation and influence of meteorological parameters. A total of 548,309.68 spores/m³ were recorded which belong to anamorphs of Higher Fungi (69.18 %), Phyla Ascomycota (12.62 %), Basidiomycota (8.01 %), Oomycota (0.37 %) and Myxomycota (0.06 %). Airborne spores occurred in Montevideo throughout the whole year. However, a seasonal pattern was revealed, with the highest concentrations recorded in autumn and summer. The most abundant spore types were Cladosporium (53.22 %), Alternaria (6.62 %), Didymella Group (5.86 %), Leptosphaeria Group (4.37 %) and Coprinus (4.3 %). Temperature appeared to be the most influential meteorological factor correlating significantly and positively with total spore, Cladosporium, Alternaria and Didymella Group abundance. Relative humidity influenced positively total spore, Cladosporium and Didymella Group concentrations while a weak negative association was obtained for Alternaria. Wind speed correlated negatively with total spore, Cladosporium, Alternaria and Didymella Group. Precipitation showed a negative influence on Alternaria, while positive correlations were observed for Didymella Group. For the first time, fungal spores considered allergenic were recorded in Montevideo atmosphere and the risk of exposure would have been high from December to June. However, long-term sampling is needed to define seasonal prevalence patterns and the influence of meteorological conditions on spore abundance.     

Fungi in the indoor environment of flour mill in Lucknow

Forty species of fungi were recovered from the indoor air of flour mills by exposing petri plates containing potato dextrose, czapek-dox, and sabouraud agar media for 5 minutes. A rotorod sampler was used. The fungal flora of the nearby outdoor environment was also studied for comparison. Species of genus Aspergillus dominated in the mills, being represented by 16 species including one ascosporic species. Other species were of genera Cladosporium and Fusarium. Variations in the fungal population in different months of the survey year were also observed.

Identifiable fungal spores recovered using the rotorod sampler were Alternaria (17% occurrence), Curvularia lunata (10.6%), C. letramera (10%), Cladosporium (19%), Drechslera sp. (9%), Epicoccum sp. (5%), Pithomyces sp. (3%), Nigrospora sp. (10.5%), Stemphylium sp. (4.5%) and Torula sp. (4.5%). Mycelial fragments and unidentifiable spores were also seen in abundance.

Varying allergic responses of patients tested intradermally for the antigens of six Aspergilli, viz., Aspergillus flavus, A. fumigatus, A. melleus, A. niger, A. niveus, and A. terreus were also recorded.     

Study of endophytic fungal community from different parts of <Emphasis Type="Italic">Aegle marmelos</Emphasis> Correae (Rutaceae) from Varanasi (India)

Endophytic fungi were isolated from healthy, living, and symptomless tissues of inner bark, leaf, and roots of Aegle marmelos, a well-known medicinal plant, growing in different parts of India including Varanasi. A total of 79 isolates of endophytic fungi were isolated, representing 21 genera, adopting a standard isolation protocol. Members of the deuteromycotina were more prevalent than ascomycotina and others. The result was quite encouraging in terms of maximum isolates recovery from hyphomycetes (78.5%) followed by ascomycetes (8.9%) and coelomycetes (7.6%) respectively, which corroborates previous studies in same area. However, 5.1% isolates remained unidentified and were classified under Mycelia Sterilia. No isolate was obtained from either basidiomycotina or from zygomycotina. Fusarium spp. had maximum colonization frequency (8.00%) in this plant. The other dominant endophytic genera were Aspergillus spp., Alternaria sp., Drechslera sp., Rhizoctonia sp., Curvularia sp., Nigrospora sp., and Stenella sp. Only two ascomycetous members Chaetomium globosum and Emericella sp. (perfect state of Aspergillus sp.) were obtained from the bark sample. These results indicated that distribution of endophytic fungi within the A. marmelos is not even. Bark harbors more endophytic fungi than leaf and root.     

Aeromycoflora of an agricultural farm in West Bengal,India: A five-year study (1994–1999)

A five-year (1994–1999) continuous survey of aeromycoflora had been carried out in an agricultural farm at a suburban area of Greater Calcutta. The sampling was carried out with Burkard volumetric spore trap placed 0.5?meter above the ground level at the centre in a small plot in a rice field. A total of 26 fungal spore types were identified microscopically. The most abundant types were Basidiospores (21.85–5.59%) followed by Cladosporium, Periconia, Nigrospora, Aspergilli group, Ascospores. The seasonal periodicity of the major dominant types had maxima in autumn, during the month of October. This coincided with the harvesting period of the rice crop during rainy season. In Petri plate exposure of nutrient media, different species of aspergilli group, Alternaria, Cladosporium, Curvularia, Nigrospora, and other taxa were identified. The diurnal periodicities recorded for different types were classified into night-time, post dawn, middle day and double maxima (showing two peaks in a day) patterns. In general, no significant correlation between the total air spora and the meteorological parameters could be established. It is evident that the local cropping practices may have some regulating role on spore concentration in the air of the study area.     

青枯病与黑胫病混发烟株发病茎秆组织微生物群落结构与多样性

为了解青枯病与黑胫病混发烟株茎秆组织的微生物菌群组成,该文采用Illumina Miseq高通量测序技术研究了青枯病与黑胫病混发烟株发病茎秆和健康烟株未发病茎秆组织的真菌、细菌群落结构与多样性.结果表明:(1)发病茎秆组织中真菌群落丰富度与多样性较健康茎秆组织低,细菌群落丰富度与多样性较健康茎秆组织高.(2)健康茎秆组...