Individual and combined effects of berberine and santonin on spore germination of some fungi

Berberine and santonin were isolated from rhizomes ofBerberis aristata and unexpanded flower buds ofArtemisia maritima, respectively. Efficacy of these two chemicals individually as well as of their mixtures, was tested against spore germination of some saprophytic and obligate fungi. While berberine individually was effective against most of the fungi,Helminthosporium spp. were least affected even at the highest dose (1500 ppm). Santonin was equally effective against several fungi. Mixture of both alkaloids found to be more effective than individual ones. Keeping the dose of berberine constant and santonin at two different concentrations (viz. 250 and 500 ppm) the spore germination ofHelminthosporium, oryzae was stimulated. Increasing concentration of santonin inhibited the spore germination of all other fungi tested,Colletotrichum capsici being affected only by 20 and 5% (at berberine concentration of 250 and 500 ppm, respectively). On the other hand, santonin being constant and berberine at different concentrations, the mixture was effective against all the fungi.     

Seasonal incidence of airborne fungal allergens in Riyadh,Saudi Arabia

Aerobiological studies to evaluate allergenic fungal spores in the atmosphere of Riyadh were conducted. Burkard personal volumetric sampler were operated as volumetric viable spore traps at two different sites (Al-Batha, a more developed area in the south and Al-Ulia, a less developed area in the north) in Riyadh. Twice a week samplings were carried out over a period of 12 month. The seasonal fluctuations of the most frequent fungi were plotted as major components. The dominant species at the two sites were members of the genera Alternaria, Aspergillus, Cladosporium, Penicillium and Ulocladium. Drechslera, Fusarium, Rhizopus and Stachybotrytis species were minor components or sporadic. Seasonal variations of the total colonies were significantly (p < 0.05) different. They showed higher concentrations in the winter season and the lowest in summer. The Al-Batha site was always higher in spore concentrations than the Al-Ulia site. The results provide valuable information for the diagnosis and prophylaxis of allergic diseases due to airborne fungi.This revised version was published online in October 2005 with corrections to the Cover Date.     

Circadian periodicity of airborne pollen and spores; significance of sampling height

Summary The circadian periodicity of the five allergologically most important pollen types in S. Finland and two different spore types were studied at two sites, about 200 meters apart: one Burkard sampler situated on a roof at a height of 15 meters and the other on a garden lawn at ground level. The circadian rhythms of pollen released close to the ground (herb pollen) did not correlate at the two sampling heights used. Variations in pollen from high sources (trees) were significantly correlated at the two heights used. The circadian rhythms of spores from low source distant from the sampling sites (Suillus as an example of forest fungi) were not always correlated; instead, spores with sources at different heights (Cladosporium as an example) had similar circadian periodicity not depending on the sampling level. It was shown that, when studying circadian rhythms of atmospheric particles, the sampling height used is often of great importance. Circadian rhythms of the same pollen and spore types for ten years at the higher sampling site are presented for long-term comparison.     

Seasonal variation of arbuscular mycorrhizal fungi in temperate grasslands along a wide hydrologic gradient

We studied seasonal variation in population attributes of arbuscular mycorrhizal (AM) fungi over 2 years in four sites of temperate grasslands of the Argentinean Flooding Pampas. The sites represent a wide range of soil conditions, hydrologic gradients, and floristic composition. Lotus glaber, a perennial herbaceous legume naturalised in the Flooding Pampas, was dominant at the four plant community sites. Its roots were highly colonised by AM fungi. Temporal variations in spore density, spore type, AM root colonisation, floristic composition and soil chemical characteristics occurred in each site and were different among sites. The duration of flooding had no effect on spore density but depressed AM root colonisation. Eleven different types of spores were recognized and four were identified. Two species dominated at the four sites: Glomus fasciculatum and Glomus intraradices. Spore density was highest in summer (dry season) and lowest in winter (wet season) with intermediate values in autumn and spring. Colonisation of L. glaber roots was highest in summer or spring and lowest in winter or autumn. The relative density of G. fasciculatum and G. intraradices versus Glomus sp. and Acaulospora sp. had distinctive seasonal peaks. These seasonal peaks occurred at all four sites, suggesting differences among AM fungus species with respect to the seasonality of sporulation. Spore density and AM root colonisation when measured at any one time were poorly related to each other. However, spore density was significantly correlated with root colonisation 3 months before, suggesting that high colonisation in one season precedes high sporulation in the next season.     

Interaction of vascular plants and vesicular-arbuscular mycorrhizal fungi across a soil moisture-nutrient gradient

Summary Abundance and distribution of vascular plants and vesicular-arbuscular mycorrhizal (VAM) fungi across a soil moisture-nutrient gradient were studied at a single site. Vegetation on the site varied from a dry mesic paririe dominated by little bluestem (Schizachyrium scoparium) to emergent aquatic vegetation dominated by cattail (Typha latifolia) and water smartweed (Polygonum hydropiperoides). Plant cover, VAM spore abundance, plant species richness, and number of VAM fungi represented as spores, had significant positive correlations with each other and with percent organic matter. The plant and VAM spore variables had significant negative correlations with soil pH and available Ca, Mg, P and gravimetric soil moisture. Using stepwise multiple regression, Ca was found to be the best predictor of spore abundance. Test for association between plant species and VAM fungal spores indicated that the spores of Glomus caledonium are associated with plants from dry, nutrient poor sites and spores of gigaspora gigantea are positively associated with plants occurring on the wet, relatively nutrient rich sites. Glomus fasciculatum was the most abundant and widely distributed VAM fungus and it had more positive associations with endophyte hosts than the other VAM fungi. We found no relationship between beta niche breadth of plant species and the presence or absence of mycorrhizal infection. However, our data suggest that some plant species may vary with respect to their infection status depending upon soil moisture conditions that may fluctuate seasonally or annually to favor or hinder VAM associations.     

EFFECT OF ROCKY INTERTIDAL AMPHIPODS ON ALGAL RECRUITMENT: A FIELD STUDY1

Evidence about the potential of mobile marine invertebrates to act as algal spore dispersal agents is presently circumstantial. Using a field correlational and experimental protocol, our study tested the hypothesis that amphipods can increase the spore recruitment of the red alga Iridaea laminarioides Bory. Iridaea laminarioides spore recruitment onto glass slides was measured at a site with high amphipod abundance and a site with low density of amphipods. To evaluate the effect of an Ulva canopy on recruitment, replicated glass slides with and without a surrounding Ulva canopy were installed at both sites. The number of I. laminarioides spores recruited on the glass slides was four to eight times higher at the high amphipod abundance site than at the low density site. However, the presence of an Ulva canopy covering the glass slides did not significantly increase the recruitment of I. laminarioides. Because the abundance of I. laminarioides, the proportion of cystocarpic plants, and the percentage of open cystocarps only differed slightly between the low and high abundance amphipod sites, we suggest that the variation in recruitment between the sites is due to the differences in amphipod abundance (and their movements) and not to differences in spore production. Moreover, the presence of I. laminarioides cystocarps showing amphipod grazing scars was significantly higher at the high amphipod density site than at the low density site.     

Airborne fungal spores in urban and rural environments in Poland

The concentrations of airborne fungal spores were measured during 2001–2002 in two sites in Poland—one in the city and the other in the countryside. The sites differed in habitat characteristics, such as urbanisation level, vegetation and microclimate. The aim of the study was to determine if, and in which way, land use type would affect spore occurrence. The volumetric method was used, and ten easily identifiable spore types were sampled and anyalysed: Alternaria, Botrytis, Cladosporium, Epiccocum, Ganoderma, Pithomyces, Polythrincium, Stemphylium, Torula and Drechslera. The season of spore occurrence was determined using the 90% method. The fungal spores studied were very frequent in the air (in most instances at a frequency higher than 50%). The most common spores were those of Cladosporium, with a frequency range of 83.1–90.5%. In both years the proportion of Cladosporium spores was statistically significantly higher in the city. In both 2001 and 2002 the total seasonal sum of all the spores was higher in the countryside than in the city as was the Seasonal Fungal Index (SFI) values and average concentrations of Botrytis, Ganoderma and Torula. These latter three genera are usually represented as pathogens of plants. The mean spore concentrations of most taxa were significantly higher in the rural environment. Correlation coefficients between daily concentrations at both sites for most of the taxa studied were significant, but with lower correlation values between variables. Such results indicate that the values from the sites are weakly interdependent. The study confirms that land use type may very likely have an impact on the course of spore occurrence, the mean daily concentrations of spores as well as SFI values.     

In vivo control of Mycosphaerella pinodes on pea leaves by a crude bulb extract of Eucomis autumnalis

We previously reported on the in vitro antifungal activity of a crude whole plant extract from Eucomis autumnalis against seven economically important plant pathogenic fungi. A crude extract of the bulb showed similar in vitro mycelial growth inhibition of the same plant pathogenic fungi as well as that of an eighth fungus, Mycosphaerella pinodes, the cause of black spot or Ascochyta blight, in peas. Subsequently, fourth internode leaves were removed from 4 wk old pea plants, placed on moist filter paper in Petri dishes and inoculated with an M. pinodes spore suspension before and after treatment with the extract. The control of Ascochyta blight by different concentrations of the crude E. autumnalis extract was followed in vivo by leaf symptoms over a 6 day period at 20°C in a growth cabinet. The crude extract prevented M. pinodes spore infection of the leaves when the leaves were inoculated with spores both before or after treatment with the extract, confirming complete inhibition of spore germination. The crude E. autumnalis extract showed no phytotoxic reaction on the leaves even at the highest concentration applied.     

The incidence of fungal spores in the ambient air and inside homes: Evidence from London

Little research has been carried out in London concerning fungal spore prevalence yet this information may help to elucidate geographical patterns of asthma and hay fever. Although many types of spore reach peak concentrations outdoors in late-summer, the incidences in the indoor environment may be more important through the winter because of heating and poor ventilation. Daily average concentrations of fungal spores in the ambient atmosphere were monitored with a Burkard volumetric spore trap on an exposed roof in North London from autumn 1991 until the summer of 1992. Indoor spore measurements were taken in 19 homes in the vicinity through the winter months, both by direct air sampling using a portable Burkard sampler and by dust culture. Trends in the occurrence and concentrations of fungal spores indoors and outdoors were examined. Relationships between the abundance of selected allergenic fungi and features of the houses were analysed including age of dwelling, dampness, cleanliness and presence of pets.Aspergillus andPenicillium were the most frequently occurring spore types in the homes. Overall, high spore incidence was associated with dampness and dust accumulation. The outdoor spore samples revealed generally low concentrations through the winter until March when concentrations of many types includingCladosporium, Epicoccum andAlternaria increased in abundance in response to the warmer weather. Even during the late-spring and early-summer, concentrations of most fungal spores were notably below those reported for rural sites.     

毛乌素沙地沙打旺根围AM真菌的空间分布

对毛乌素沙地5个不同生态条件下沙打旺(Astragalus adsurgens)根围土壤0～50 cm土层 AM真菌空间分布进行研究.结果表明：不同样地和采样深度下AM真菌孢子密度和定殖率存在显著差异,最高定殖率和最大孢子密度均出现在10～30 cm土层; 定边样地孢子密度最高,并显著高于其他样地;塔湾样地菌丝和总定殖率最高,宁条梁和塔湾样地泡囊定殖率高于其他样地.总球囊霉素(TG)和易提取球囊霉素(EEG)含量均在塔湾样地最高,分别为1.18 mg·g^-1和0.65 mg·g^-1.土壤pH对孢子密度、泡囊和丛枝定殖率、TG和EEG均有极显著正效应,TG和EEG分别与孢子密度、土壤有机C、碱解N和速效P呈极显著正相关.沙漠土壤球囊霉素占有机C的比例高于农田土壤,可能是沙漠土壤有机C的主要来源之一.球囊霉素可作为评估沙漠土壤AM真菌活动和土壤生态状况的有效指标.     

Trace metal biomonitoring in the soil and the leaves ofQuercus ilex in the urban area of Naples

The concentrations of Pb, Cu, Fe, and Mn were analyzed in surface deposit and tissue ofQuercus ilex leaves from several sites of the urban area of Naples, exposed to different degrees of air pollution. These included some major roads with heavy traffic loads, squares, and three urban parks. The soil from the trunk base area ofQ. ilex trees in the same sites was also analyzed for total and available metal contents. Pb, Cu, and Fe contents in the surface deposit and leaf tissue were significantly higher (p<0.01) in leaves from roadside sites than in leaves from parks; significant correlations were found between deposit- and tissue-contents of Pb, Cu, and Fe. Mn content in leaves from roadside sites and in leaves from parks were similar and Mn content in the leaf deposit was irrelevant. Significant differences (p<0.001) in both total and available Pb and Cu soil content were found between sampling sites. Also for available Fe and Mn soil content differences among sites were relevant, although the highest values were measured in soil from urban parks. A positive correlation between leaf and soil metal content was found only for Pb, thus suggesting that trace metal contents of leaves directly depend on atmospheric depositions. Seasonal variations of Pb, Cu, and Fe were pronounced at a polluted site, whereas no relevant seasonal variation was observed at a control site; moreover, metal accumulation was high at the polluted site. Mn content and seasonal dynamics were comparable at control and polluted sites.     

Mycophagy in small mammals: A comparison of the occurrence and diversity of hypogeal fungi in the diet of the long-nosed potoroo Potorous tridactylus and the bush rat Rattus fuscipes from southwestern Victoria,Australia

Abstract Three broad dietary categories—fungus, plant and arthropod—were identified from faecal samples of two species of small terrestrial mammal in forest vegetation in southwestern Victoria. Fungal material formed the major component of the diet of the long-nosed potoroo Potorous tridactylus throughout the year and of the bush rat Rattus fuscipes during autumn and winter. Fungal material was most abundant for both species during autumn and winter and significantly less common in spring and summer. These results confirm previous studies which found P. tridactylus to be highly mycophagous throughout the year and R. fuscipes to be strongly mycophagous seasonally. Particular consideration was given to the composition of fungi in the diet. Fungal spores in faecal material were assigned to spore classes, which represent one or more fungal species that have similar spore morphology. Twenty-four fungal spore classes were recorded, but for both animal species most of the fungi consumed were from seven major spore classes. The proportions of major spore classes in the diet of both animals were generally similar, even though the composition of spore classes differed markedly across seasons. Minor differences between species in the fungi consumed may be related to differences in selectivity, foraging, or microhabitat use. If fungal resources are limiting, competition for such resources may be important in this and other small mammal communities. The amount and diversity of hypogeal fungi consumed by the two animal species makes them both important spore dispersal agents in forest ecosystems. The capacity of R. fuscipes and other seasonally mycophagous mammals in this role may be more important than previously recognized, especially in habitats where species of the Potoroidae are absent.     

Contrasts between subsurface microbial communities and their metabolic adaptation to polycyclic aromatic hydrocarbons at a forested and an urban coal-tar disposal site

The abundance and distribution of microorganisms and their potential for mineralizing polycyclic aromatic hydrocarbons (PAHs) were measured in subsurface sediment samples at two geographically separate buried coal-tar sites. At a relatively undisturbed forested site in the northeastern United States, metabolic adaptation to the PAHs was evident: Radiolabeled naphthalene and phenanthrene were converted to ¹⁴CO₂ in core material from inside but not outside a plume of groundwater contamination. However, at the urban site in the midwestern United States these PAHs were mineralized in sediments from both contaminated and uncontaminated boreholes. Thus, clear qualitative evidence showing an adaptational response by the subsurface microbial community was not obtained at the urban site. Instead, subtler clues suggesting metabolic adaptation by subsurface microorganisms from the urban site were discerned by comparing lag periods and extents of ¹⁴CO₂ production from radiolabeled PAHs added to samples from contaminated and uncontaminated boreholes. Despite slightly higher PAH mineralization activity in contaminated borehole samples, p-hydroxybenzoate was mineralized equally in all samples from the urban site regardless of location. No striking trends in the abundances of actinomycetes, fungi, and either viable or total bacteria were encountered. However, colonies of the soil bacterium, Bacillus mycoides, were detected on enumeration plates of several samples from unsaturated and saturated zones in both urban boreholes. Furthermore, other common soil bacteria, Myxococcus xanthus and Chromobacterium violaceum, were identified in samples from the uncontaminated urban borehole. The occurrence of bacteria usually restricted to surface soil, combined with the observation of fragments of building materials in many of the core samples, suggested that past excavation and backfilling operations may have caused mixing of surface soil with subsurface materials at the urban site. We speculate that this mixing, as well as non-coal-tar-derived sources of PAHs, contributed to the PAH-mineralizing activity present in the sediment samples from the uncontaminated urban borehole.     

Ectomycorrhizal, vesicular-arbuscular and dark septate fungal colonization of bishop pine (Pinus muricata) seedlings in the first 5 months of growth after wildfire

 We followed the colonization frequency of ectomycorrhizal (EM), vesicular-arbuscular mycorrhizal (VAM), and dark septate (DS) fungi in 1- to 5-month-old bishop pine seedlings reestablishing after a wildfire. Seedlings were collected on a monthly basis at either a VAM-dominated chaparral scrub site or an EM-dominated forest site, both of which were burned. In both vegetation types, fully developed EM were observed from the third month after germination. EM fungi observed on the seedlings from the scrub site were limited to Rhizopogon subcaerulescens, R. ochraceorubens and Suillus pungens. Seedlings from the forest were colonized by a greater variety of EM fungi including Amanita spp., Russula brevipes and a member of the Cantharellaceae. VAM structures (vesicles, arbuscules or hyphal coils) were observed in the seedling root systems beginning 1 month after germination at the scrub site and 3 months after germination at the forest site. Seedlings from the scrub site consistently had more frequent VAM fungal colonization than those from the forest site through the fifth month after germination. DS fungi were observed in most seedlings from both the scrub and forest sites beginning in the first month post-germination. We propose that these fungi survived as a resident inoculum in the soils and did not disperse into the sites after the fire. Accepted: 14 February 1998     

Intradiurnal periodicity of fungal spore concentrations (Alternaria, Botrytis, Cladosporium, Didymella, Ganoderma) in Cracow, Poland

Aerobiological monitoring enables the definition of seasonal fungal spore concentrations and also intradiurnal time when the highest concentrations of spores could cause or increase allergy symptoms. These data are useful to estimate symptoms of disease, duration of infection and how advanced the illness is in people suffering from fungal allergens. The aim of the study was to compare the concentrations of fungal spores (Alternaria, Botrytis, Cladosporium, Didymella, Ganoderma) during dry and rainy periods and to analyse their intradiurnal changes. Average daily spore concentrations in dry and rainy periods were compared, using z test, separately for each taxon, season and for a combined 3-year period. Intradiurnal periodicity of fungal spore concentrations was analysed on the basis of three complementary diagrams. These spore concentrations were presented using three curves for all, dry and rainy days in 1997–1999 (April–November). The spore percentage in particular hours was normalized in relation to the daily spore sum accepted as 100%. Two further diagrams enabled the more precise analysis of the highest concentrations in dry days. Daily Botrytis and Cladosporium spore concentrations did not show significant differences between dry and rainy periods. In the case of Didymella and Ganoderma spore concentrations, there were no significant differences between both weather types in the single years, although there was a significant difference when a 3-year period was considered. The differences between daily concentrations of Alternaria spores in dry and rainy periods occurred in 1997 and in a 3-year period. Intradiurnal periodicity of spore concentrations was different for ‘dry’ and ‘wet’ fungal spores. Dry spores are released from the spore-producing parts of the fungus under conditions of decreasing humidity and increasing airflow. Examples of dry spores are those from Alternaria, Cladosporium and Botrytis. Wet spores, such as those from many Ascomycetes (Didymella) and Basidiomycetes (Ganoderma), are released into the atmosphere by processes related to humidity conditions or rain. The highest concentrations of ‘dry’ spores were observed early in the afternoon, while highest values of ‘wet’ spore concentrations occurred in the predawn hours. Statistically non-significant differences between daily spore concentrations in dry and rainy periods of single seasons were found except for Alternaria. Statistically significant differences could occur when the studied period was longer than one season (Alternaria, Didymella, Ganoderma). The highest concentrations of Alternaria, Botrytis and Cladosporium spores were recorded at noon and early in the afternoon. Concentrations of Didymella and Ganoderma spores were highest in the predawn hours.     

Spore Composition in a Garbage Disposal Plant

The municipal garbage disposal plant in Turku converts all household garbage into ash by burning it in specially constructed ovens. For several years, the workers there have been complaining of allergy and skin diseases. An investigation was started in January, 1977, to determine the frequencies of pathogenic and allergenic fungi in the air inside this plant. The survey is being made four times during 1977 (two of these have already been carried out), using both Petri dish method and Hirst-Burkard traps. The spore trap collections indicate that the seven sampling sites can be classified into three groups with regard to spore frequencies: (1) the dumping room and the room for crushing the wastes show extremely high frequencies (170 000-180 000 spores/m³), with Penicillium and Aspergillus as the main spore types. (2) In the furnace unit the frequencies are clearly higher than in normal indoor air (over 10 000 spores/m³). (3) In the washing, dressing and control rooms the frequencies are about the same as in the indoor air in general, or even lower. The Petri dish collections gave similar results; e.g. the concentrations of Penicillium and Aspergillus in the dumping room are 6000-fold when compared with the outdoor air. The wide variations in the spore contents are directly correlated with the kind of garbage under treatment. The outdoor air collected at a distance of c. 200m showed no conspicuous differences when compared with the air in Turku in general. These results indicate that it is absolutely necessary to use face masks—at least in the dumping room conditions.     

Fungal Epiphytes and Endophytes of Coffee Leaves (Coffea arabica)

Plants harbor diverse communities of fungi and other microorganisms. Fungi are known to occur both on plant surfaces (epiphytes) and inside plant tissues (endophytes), but the two communities have rarely been compared. We compared epiphytic and endophytic fungal communities associated with leaves of coffee (Coffea arabica) in Puerto Rico. We asked whether the dominant fungi are the same in both communities, whether endophyte and epiphyte communities are equally diverse, and whether epiphytes and endophytes exhibit similar patterns of spatial heterogeneity among sites. Leaves of naturalized coffee plants were collected from six sites in Puerto Rico. Epiphytic and endophytic fungi were isolated by placing leaf pieces on potato dextrose agar without and with surface sterilization, respectively. A total of 821 colonies were isolated and grouped into 131 morphospecies. The taxonomic affinities of the four most common nonsporulating fungi were determined by sequencing the nuclear ribosomal internal transcribed spacer (ITS) region: two grouped with Xylaria and one each with Botryosphaeria and Guignardia. Of the most common genera, Pestalotia and Botryosphaeria were significantly more common as epiphytes; Colletotrichum, Xylaria, and Guignardia were significantly more common as endophytes. Suprisingly, more morphospecies occurred as endophytes than as epiphytes. Differences among sites in number of fungi per plant were significant. Thus epiphytic and endophytic communities differed greatly on a single leaf, despite living only millimeters apart, and both communities differed from site to site. Significant correlations between occurrence of fungal morphospecies suggested that fungi may have positive or negative effects on their neighbors. This is the first quantitative comparison of epiphytic and endophytic fungal floras in any plant, and the first to examine endophytic fungi or epiphytic fungi in leaves of coffee, one of the world’s most valuable crops.     

The impact of wildfire on vesicular-arbuscular mycorrhizal fungi and their potential to influence the re-establishment of post-fire plant communities

Wildfires are a typical event in many Australian plant communities. Vesicular-arbuscular mycorrhizal (VAM) fungi are important for plant growth in many communities, especially on infertile soils, yet few studies have examined the impact of wildfire on the infectivity of VAM fungi. This study took the opportunity offered by a wildfire to compare the infectivity and abundance of spores of VAM fungi from: (i) pre-fire and post-fire sites, and (ii) post-fire burned and unburned sites. Pre-fire samples had been taken in May 1990 and mid-December 1990 as part of another study. A wildfire of moderate intensity burned the site in late December 1990. Post-fire samples were taken from burned and unburned areas immediately after the fire and 6 months after the fire. A bioassay was used to examine the infectivity of VAM fungi. The post-fire soil produced significantly less VAM infection than the pre-fire soil. However, no difference was observed between colonization of plant roots by VAM fungi in soil taken from post-fire burned and adjacent unburned plots. Soil samples taken 6 months after the fire produced significantly more VAM than corresponding soil samples taken one year earlier. Spore numbers were quantified be wet-sieving and decanting of 100-g, air-dried soil subsamples and microscopic examination. For the most abundant spore type, spore numbers were significantly lower immediately post-fire. However, no significant difference in spore numbers was observed between post-fire burned and unburned plots. Six months after the fire, spore numbers were the same as the corresponding samples taken 1 year earlier. All plants appearing in the burned site resprouted from underground organs. All post-fire plant species recorded to have mycorrhizal associations before the fire had the same associations after the fire, except for species of Conospermum (Proteaceae), which lacked internal vesicles in cortical cells in the post-fire samples.     

Arbuscular mycorrhizal and dark septate endophyte fungal associations in South Indian grasses

We examined arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal association in 50 south Indian grasses from four different sites. AM fungal diversity was also compared among the different sites. Forty-four of the 50 grasses examined had AM association and dual association with DSE fungi occurred in 25 grasses. We report for the first time AM and DSE fungal status in 23 and 27 grasses respectively. Arum-type AM morphology was the dominant occurring in 21 grasses with typical Paris-type colonization occurring in 6 grasses. AM morphology is reported for the first time in 35 grasses. Over the different sites, spore density in the soil ranged from 5–22 per 100 g air-dried soil. Spores of 11 AM fungal taxa were isolated from the soil samples of grasses of which nine belonged to Glomus, one to Acaulospora and one to Scutellospora. No significant relationship existed between AM fungal colonization and spore numbers. Species richness was high in site II and Glomus aggregatum, Glomus viscosum and Glomus mosseae were most frequent species at different sites. Overall species diversity indices (Simpson index, Shannon-Weaver index, species equitability index) differed significantly between sites.