Percentage Of Spores Research Articles

The Effect of Different Temperatures and Moisture Levels on Survival of Calonectria pseudonaviculata in Boxwood Leaves and Twigs and as Microsclerotia Produced in Culture.

Leaves and twig sections of boxwood infected with Calonectria pseudonaviculata were incubated in sand at two moisture levels (36% [carrying capacity] and 5% water [vol/vol]) and at five temperatures (-10, 0, 10, 20, and 30°C). Percent sporulation from monthly tissue samples plated on glucose yeast-extract tyrosine media declined to zero after 5 months at 30°C and after 7 months at -10°C. At 0, 10, and 20°C, sporulation was observed through 30 months. Statistical analysis of data collected over 16 months of sampling showed a significant effect for temperature in all sample types, with maximum survival at 10°C. For discrete microsclerotia grown on cellophane sheets, sporulation was not observed after 2 months at 30°C or after7 months at -10°C. At all other temperatures, they continued to germinate over the 30 months of sampling. Statistical analysis showed significant effects for temperature and moisture level, with maximum survival at 0°C in moist soil over 16 months. These results suggest that extremes of heat and cold will kill the pathogen in plant debris but, at moderate temperatures, it will remain in soil for long periods, making replanting in affected sites in well-moderated climates difficult.

Beyond animals and plants: dynamic maternal effects in the fungus Neurospora crassa.

Maternal effects are widely documented in animals and plants, but not in fungi or other eukaryotes. A principal cause of maternal effects is asymmetrical parental investment in a zygote, creating greater maternal vs. paternal influence on offspring phenotypes. Asymmetrical investments are not limited to animals and plants, but are also prevalent in fungi and groups including apicomplexans, dinoflagellates and red algae. Evidence suggesting maternal effects among fungi is sparse and anecdotal. In an experiment designed to test for maternal effects across sexual reproduction in the model fungus Neurospora crassa, we measured offspring phenotypes from crosses of all possible pairs of 22 individuals. Crosses encompassed reciprocals of 11 mating-type 'A' and 11 mating-type 'a' wild strains. After controlling for the genetic and geographic distances between strains in any individual cross, we found strong evidence for maternal control of perithecia (sporocarp) production, as well as maternal effects on spore numbers and spore germination. However, both parents exert equal influence on the percentage of spores that are pigmented and size of pigmented spores. We propose a model linking the stage-specific presence or absence of maternal effects to cellular developmental processes: effects appear to be mediated primarily through the maternal cytoplasm, and, after spore cell walls form, maternal influence on spore development is limited. Maternal effects in fungi, thus far largely ignored, are likely to shape species' evolution and ecologies. Moreover, the association of anisogamy and maternal effects in a fungus suggests maternal effects may also influence the biology of other anisogamous eukaryotes.

Diatom assemblages from coastal settings of West Antarctica

Abstract Diatom assemblages from 33 core-tops, collected along a 2500 km transect of the northern Antarctic Peninsula and Pine Island Bay areas, were examined for their use as paleoenvironmental proxies. Environmental affinities of assemblages were interpreted within a broad geographical context and a wide range of ecological conditions. Four major assemblages were identified: three pelagic assemblages related to different sea-ice duration, SST, and other conditions affecting primary production, and one benthic and epiphytic-dominated assemblage typical of near-shore, shallow-water habitats. Chaetoceros resting spores are an important component of diatom assemblages. Their high concentrations may reflect increased primary production and are associated with low total assemblage diversities. The lowest diversities are observed at sites with increased resting spore percentages. Along the NW coast of the Antarctic Peninsula, sedimentation rates strongly influence total diatom concentrations. By contrast, relative abundances of Chaetoceros resting spores remain mostly unaffected by terrigenous flux and may serve as a reliable proxy for primary production. This broad sampling of Antarctic coastal environments fills a gap in our knowledge of phytoplankton communities in polar regions and helps establish the framework for reconstructing paleoenvironments from the paleorecord.

Diversity and Abundance of Arbuscular Mycorrhizal Fungi Under Different Plant and Soil Properties in Sidama, Southern Ethiopia

In Sidama, agroforestry represents land-use systems with deliberate management of multipurpose trees and shrubs that grow in intimate association with annual and perennial agricultural crops and/or livestock. The interaction of microbiota with the trees, shrubs and crops make the system fertile, productive and sustainable. One of the beneficial microbiota which has symbiotic association with most of the plants in agroforestry is arbuscular mycorrhizal fungi (AMF). In November and December of 2012, root and rhizosphere soil samples of 21 plant species from nine peasant associations (PAs)(villages within districts where 300-500 families live) were collected from the agroforestry practices in Sidama of Southern Ethiopia for the determination of diversity and abundance of AMF under selected soil parameters and plant species density. Findings on the diversity of AMF based on soil properties showed that at moderate to low P and N concentrations the rate of AMF root colonization and spore density was high in comparison with the rhizosphere soils with the highest P and N concentration. The highest percentage of total AMF colonization was recorded for shade trees Millettia ferruginea (84%) and Erythrina brucei (80%) followed by intercropped perennial crops Ensete ventricosum (86%), Catha edulis (85%) and Coffea arabica (80%) and the lowest percentage AMF colonization was recorded for Rhamnus prinoides (53%) and Colocasia esculenta (52%). Though found in almost all homegarden agroforestry practices and with broad coverage in Sidama agroforestry, some crops and vegetables such Brassica integrifolia and Cucurbita pepo, grown intercropped were found to be non-mycorrrhizal as none of the AMF structures were recorded. The highest number of AM spore population was recorded in rhizosphere soils of Croton macrostachyus (1066±19.33) and Catha edulis (1054±53.12) and the lowest spore density was recorded for Dioscorea alata (100.00±2.89) spore per 100 g of dry soil. The percentage fungal colonization in any individual plant species and spore population in the rhizosphere soils of that species did not correlate to each other and percentage AM root colonization and spore density of all plants in the agroforestry of Sidama were found significantly different at P<0.05 level.

Potential of pre-harvest application of Burkholderia spinosa for Biological control of epiphytic and pathogenic microorganisms on the phyllosphere of banana (Musa spp.)

A study was conducted to determine the effects of pre-harvest application of a bacterial antagonist, Burkholderia spinosa on the population dynamics of epiphytic and pathogenic microorganisms dwelling on banana ( Musa spp.) leaves together with the population build-up of the applied bacterial antagonist. Banana cultivar Kolikuttu was established as an outdoor plot experiment and the antagonist was applied by two methods (i.e. a foliar spray and a soil drench) at nine times (i.e. 300 ml per plant per time) repeatedly at weekly intervals. Effects of leaf washings of plants treated with different application methods on germination of C. musae , the causal organism of several postharvest diseases of banana, spores were investigated in vitro . There was a significant (p B. spinosa application on the density of the bacterial antagonist on banana leaves. A gradual build-up of B. spinosa was observed on leaves with a peak density at 228 days after planting when bacterial antagonist was applied as a foliar spray. Burkholderia spinosa was not found on leaves of banana when the plants were treated as a soil drench or left untreated with the antagonist. Densities of Aspergilus spp. And unidentified fungal species on leaves of banana were significantly influenced by the method of application of B. spinosa . In contrast, density of Fusarium spp. on the banana phyllosphere varied significantly with the time of application (p Aspergillus spp. and Fusarium spp. Percentage germination of C. musae spores continued to increase 24 h after incubation in the leaf washing of control banana plants. In contrast, leaf washings of B. spinosa treated plants showed a decline in the percentage spore germination. The findings of the present study revealed the ability of B. spinosa for building up considerable cell densities on the treated leaf surface and its ability for suppressing a range of microbes. These are desirable features of B. spinosa to be used in field application for the control of foliar pathogens of banana. Tropical Agricultural Research Vol. 25 (4): 543 – 554 (2014)

Studies on Antifungal Potential, Primary Characterization and Mode of Action of a De Novo Cytoplasmic Protein (EAF) from Human Commensal Escherichia coli Against Aspergillus spp.

A de novo protein named as EAF (Escherichia antifungal protein) from the cytoplasmic pool of an Escherichia coli strain (MTCC 1652), has been purified to homogeneity using anion exchange (Q-XL Sepharose) and cation exchange (SP-Sepharose) chromatography. The MIC (minimum inhibitory concentration) values of purified protein against A. fumigatus (the major pathogenic species) were found to be comparable with standard drugs i.e. 3.90 µg/ml, 3.90 µg/ml and 1.25 µg/disc via microbroth dilution assay (MDA), percentage spore germination inhibition (PSGI) and disc diffusion assay (DDA) respectively. Toxicity results confirmed that it causes no haemolysis against human RBCs upto a concentration of 1000.0 µg/ml as compared to Amphotericin B (conventional antifungal drug) that causes hundred percent haemolysis at a concentration of 37.50 µg/ml only.The purified protein demonstrated a molecular mass of 28 kDa on SDS-PAGE which was further authenticated by MALDI-TOF. Proteomic and bioinformatics studies deciphered its significant homology (72 %) with chain A-D-ribose binding protein (cluster 2 sugar binding periplasmic proteins; sequence homologues of transcription regulatory proteins) from E. coli. Single dimensional page analysis of A. fumigatusproteins with due effect of EAF (at MIC50) revealed the inhibition of two major proteins; a heat shock protein 70-Hsp70 (68 kDa); having role in protein folding and functioning andphenylanalyl-t RNA synthetase PodG subunit protein (74 kDa); involved in growth polarity in fungi. Scanning electron microscopic studies depicted homologous results. We suggest that EAF most likely belongs to a new group of proteins with potent antifungal characteristics, negligible toxicity and targeting vital proteins of fungal metabolism.

Endophytes from wheat as biocontrol agents against tan spot disease

Endophytes from wheat cultivars isolated in Buenos Aires province, Argentina, were assessed for their potential as biocontrol agents against Pyrenophora tritici-repentis (Died.) Drechsler (anamorph Drechslera tritici-repentis) (Died.) Shoem (Dtr), the causal agent of tan spot of wheat. Endophytes were screened using dual culture techniques and examining the effect on growth, sporulation and the antifungal activity in greenhouse assays. The most of endophytes tested significantly reduced Dtr growth compared to the control except Rhodotorula rubra from 11 to 15days post inoculation. Trichoderma hamatum, Penicillium sp., Bacillus sp. and Paecilomyces lilacinus significantly reduced the colony diameter of the pathogen. Most of the endophytes evaluated showed morphological changes in the conidia and/or the mycelia of D. tritici-repentis. In addition, two endophytes, Bacillus sp. and Fusarium sp., reduced significantly the percent spore germination of Dtr compared to the control by 82% and 52% respectively. In greenhouse experiment T. hamatum, Chaetomium globosum and Fusarium sp. significantly (P⩽0.05) reduced the average disease severity on all three leaves compared to the control. However, the best antagonistic effect was shown with T. hamatum as it resulted in the greatest suppression in the greenhouse and in the dual-plate assays. Likewise, Bacillus sp. was other highlighted microorganism that antagonized the pathogen in in vitro assays. From our promising results, we conclude that endophytes have potential in the biological control of tan spot of wheat caused by D. tritici-repentis, particularly T. hamatum and Bacillus sp.

Sporulation dynamics and spore heat resistance in wet and dry biofilms of Bacillus cereus

Environmental conditions and growth history can affect the sporulation process as well as subsequent properties of formed spores. The sporulation dynamics was studied in wet and air-dried biofilms formed on stainless steel (SS) and polystyrene (PS) for Bacillus cereus ATCC 10987 and the undomesticated food isolate B. cereus NIZO 4080. After harvesting and maturation, the wet heat resistance of spores obtained from these biofilms was tested and compared to planktonic and agar plate-derived spores. Drying/air exposure of the preformed 24 h old biofilms accelerated spore formation for both strains and resulted in higher final spore percentages. Prolonged dry incubation of more than three days triggered germination of spores in the biofilms of ATCC 10987. Spores harvested from wet biofilms on SS displayed the highest heat resistance compared to liquid, agar plate and PS biofilm derived spores. The D95 °C values for these spores were 17 and 22 min for NIZO 4080 and ATCC 10987, respectively, which was 2 and 1.2 fold higher compared to planktonic spores of these strains. Spores obtained from dried biofilms of ATCC 10987 displayed reduced heat resistance compared to wet biofilm spores. The results indicate that environmental conditions encountered by biofilms affect sporulation dynamics and spore heat resistance, thus affecting subsequent quality issues and safety risks related to these biofilms.

A pyrosequencing-based method to quantify genetic substitutions associated with resistance to succinate dehydrogenase inhibitor fungicides in Botrytis spp. populations

The genetic underlying resistance mechanisms in the population of the phytopathogenic fungus Botrytis cinerea are well documented. Specifically, several genetic substitutions associated with succinate dehydrogenase inhibitor (SDHI)-based fungicide resistance have been identified in the succinate dehydrogenase gene. The objective of the present work was to develop a molecular tool for accurate quantification of these genetic substitutions within Botrytis populations. A test using the PyroMark Q24 instrument was designed to detect and quantify five genetic substitutions associated with SDHI resistance. The technique is based on sequencing by synthesis, and it generated quantitative and accurate data with a limit of quantification of a minimum of 500 spores. There was a linear relationship between the known and estimated percentages of spores with the targeted genetic substitutions and wild-type strains at ratios of 0-100%, with a 20% increment. With the pyrosequencing assay developed in this study, a large number of Botrytis spp. individuals can be characterised in a timely fashion with greater accuracy than by commonly used methods. Hence, pyrosequencing-based methods will be useful for improving our understanding of fungicide resistance, detecting the arrival of new genetic substitutions, monitoring shifts in fungal populations and assessing the effectiveness of antiresistance strategies, and for routine monitoring of fungicide resistance.

Fungicide Resistance of Two Species of Alternaria from Potato in the Columbia Basin of Washington.

Fungicides are extensively used in the Columbia Basin of Washington in an effort to manage early blight and brown spot on potato caused by Alternaria solani and A. alternata, respectively. Azoxystrobin and boscalid interfere with cellular respiration, and fungicide resistance is expected to occur in fungal populations due to the narrow modes of action dictated by each fungicide. The objective of this research was to assess A. solani and A. alternata populations in the Columbia Basin of Washington for azoxystrobin and boscalid resistance by initially screening isolates at a threshold concentration using mycelial growth and spore germination. Fifty isolates of A. solani and 58 of A. alternata were randomly selected for screening from 671 isolates collected from potato in the Columbia Basin from 2009 to 2011. Screening at a threshold concentration was done to estimate the range of fungicide resistance within the populations of A. solani and A. alternata in the region. Resistance of five isolates that differed in sensitivity to azoxystrobin and boscalid were then assessed for mycelial growth and spore germination at three fungicide concentrations in order to determine where rates were no longer effective. A. solani mycelial growth ratios and percent spore germination on azoxystrobin-amended media did not change from 2010 to 2011. A slight decrease in resistance of mycelial growth to azoxystrobin was exhibited among A. alternata isolates collected between 2010 and 2011. No change in sensitivity to azoxystrobin was observed in mycelial growth ratios among A. alternata isolates collected between 2010 and 2011. Resistance to boscalid by A. solani increased as indicated by a significant increase in mean mycelial growth ratio from 2010 to 2011, whereas A. alternata showed no change. Spore germination of A. solani was less at 100 μg/ml than at 1 or 10 μg/ml azoxystrobin. Spore germination of A. alternata did not differ among 1, 10, or 100 μg/ml azoxystrobin. Spore germination of A. solani and A. alternata did not differ among 0.5, 5, or 50 μg/ml boscalid. Resistance to azoxystrobin and boscalid in A. solani and A. alternata populations was shown to be present in the Columbia Basin and will likely become widespread with continued used of site-specific fungicides.

Floristic And Microbial Diversity In Different Coal Mine Overburdens And Adjacent Natural Forest Of Chhattisgarh, India

In the present study, percent AMF (Arbuscular Mycorrhizal Fungi) colonization and spore density in different overburden vegetations and in natural forest was evaluated to study the pattern of recovery of vegetation at overburdens. Total eight forest species were planted on coal mine overburdens aged 2, 3 and 5 years located in nearby areas of Korba, India. Sissoo (Dalbergia sissoo), Peltaphorum (Peltaphorum ferrugineum) and Bamboo (Dendrocalamus strictus) were best in harboring highest number of AMF. The mean root colonization in tree species was increased 61.98% in 3 years and 110.23% in 5 years compared with the species of 2 year. The dominant AMF were Acaulospora scrobiculata and Rhizophagus irregularis in 2 year overburdens and Funneliformis mosseae, Gigaspora and Sclerocystis in older overburdens and forest soil. The diversity index of AMF was found 1.80, 2.14 and 2.49 in 2, 3 and 5 year overburdens respectively while the diversity index of other soil fungi was found 1.61 in 2 years, 1.73 in 3 year and 2.10 in 5 year aged of overburdens compared to natural forest (2.21). Total 11, 25 and 29 ground species were recorded from 2, 3, 5 year overburden respectively and 25 species from the site of natural forest. The root colonization in ground vegetation was found 28.03%, 31.86% and 39.43% in 2, 3 and 5 year old re-vegetated overburden respectively in comparison to natural forest (29.08%). The status of soil pH and phosphorus was also ameliorated in older dumps.

A potential trade-off with stictic acid improves ascospore viability inXanthoparmelia cumberlandia

Abstract The goal of this paper was to explore trade-offs between fecundity and carbon based secondary metabolites (CBSM) production within the thallus of three species of Rock-shield and Ring lichens, Arctoparmelia centrifuga, Xanthoparmelia viriduloumbrina and X. cumberlandia. Fecundity was measured by numbers of apothecia per thallus, number of spores per apothecium and percent spore germination, and it was compared with the quantity of the major CBSMs produced by the thallus. Results showed negative correlations between stictic acid and all three measures of fecundity for X. cumberlandia, which are consistent with trade-offs. When thallus and apothecium quantities of CBSMs were compared, stictic acid was the only CBSM with levels in the apothecium that were significantly higher than those in the thallus supporting a function that may protect ascospores against herbivory. Other CBSMs are hypothesized to have functions associated with the thallus and UV protection of green algae.

English

The effects of sucrose, pH and plant growth hormones on spore germination percentage and gametophyte growths of Pteris tripartita were studied. Various morphological structures of gametophytes were observed namely, filamentous, spatulate and heart stages in the MS culture medium with hormones. After 15&nbsp;days, the spores of P. tripartita were sprouted in MS basal medium fortified with pH, sucrose and hormones. Maximum spore germination rates (84%) were observed in 70&nbsp;g/L of sucrose and 79.33% in pH 5.7. On the other hand, the maximum gametophyte sizes were observed both in 40 and 50&nbsp;g/l of sucrose on half strength MS medium. The maximum growth of gametophyte lengths (484.39 and 507.72&nbsp;&micro;m) and widths (846.58&nbsp;and 1270.98&nbsp;&micro;m) were observed in both pH 5.7 and 6.7. Among three different hormones, the utmost number or percentage of spores were sprouted in GA3. However, the in vitro cultures of spore having the capability to increase the spore germinated due to addition of adequate nutrition in the culture medium and also reduce the contamination as well as environmental factors. &nbsp; Key words: Pteris tripartita, spore germination, sucrose, hormone, MS medium.

On the neutralization of bacterial spores in post-detonation flows

In multiple operational scenarios, explosive charges are used to neutralize confined or unconfined stores of bacterial spores. The spore destruction is achieved by post-detonation combustion and mixing of hot detonation product gases with the ambient flow and spore clouds. In this work, blast wave interaction with bacterial spore clouds and the effect of post-detonation combustion on spore neutralization are investigated using numerical simulations. Spherical explosive charges (radius, $$R_\mathrm{C}$$ = 5.9 cm) comprising of nitromethane are modeled in the vicinity of a spore cloud, and the spore kill in the post-detonation flow is quantified. The effect of the mass of the spores and the initial distance, $$d^0$$ , of the spore cloud from the explosive charge on the percentage of spores neutralized is investigated. When the spores are initially placed within a distance of 3.0 $$R_\mathrm{C}$$ , within 0.1 ms after detonation of the charge, all the spores are neutralized by the blast wave and the hot detonation product gases. In contrast, almost all the spores survived the explosion when $$d^0$$ is greater than 8.0 $$R_\mathrm{C}$$ . The percentage of intact spores varied from 0 to 100 for 3.0 $$R_\mathrm{C}$$ $$<d^0<$$ 8.0 $$R_\mathrm{C}$$ with spore neutralization dependent on time spent by the spores in the post-detonation mixing/combustion zone.

Temperature effect on rose downy mildew development under environmental controlled conditions

The rose downy mildew disease, caused by Peronospora sparsa Berkeley, is one of the most important that affect rose crops in Colombia. To manage this disease, flower growers must deal with high-costs due to the excessive application of fungicides, but without good results. Studies on P. sparsa behavior have shown its narrow relationship with environmental conditions. In this study, the temperature effect was evaluated during the infection and sporulation of P. sparsa in Charlotte leaflets, a susceptible commercial variety, through an environmental controlled conditions system. Infection and sporulation were observed at different temperatures in a range of from 4 to 40°C. Infection with the absence of or very low sporulation was observed at 4°C. The most favorable pathogen responses were between 15 and 18°C in terms of inoculum concentration and sporulation percentage. There was no infection or leaflet change above 35°C. According to the results, sporulation can occur from 4 to 33°C, confirming the fact that P. sparsa is able to reproduce throughout a wide temperature range.

Effect of fungicides, botanicals, bioagents and Indigenous Technology Knowledge (ITKs) on germination of urediniospores of Puccinia sorghi in vitro

Tebuconazole 250 EC (4.78% urediniospores germination) was found to be significantly superior among the eight systemic fungicides evaluated in vitro condition against Puccinia sorghi at different concentrations. Among the non-systemic fungicides Mancozeb + Phyton (7.24% urediniospores germination) was found to be significantly superior followed by Mancozeb (24.44% urediniospores germination) at different concentrations screened in vitro. The fungicides revealed higher efficacy with the increase in concentration levels. Among the botanicals tested, Neemazol F5% caused significantly less percent spore germination (6.55%) followed by Nimbicidine (6.83%) at different concentrations and Trichoderma harzianum at 108spores/ml was recorded significantly less percent germination (31.07%) followed by Bacillus subtilis(43.42%) and Pseudomonas flourescens (53.39%) evaluated in vitro condition against P. sorghi at different concentrations. Jeevamruta at 20% concentration caused significantly less percent germination (22.69%) followed by Panchyagavya at 20% (33.67%). Key words: Botanical, bioagent, common rust, fungicide, Indigenous Technology Knowledge (ITK’s), in vitro bioassay, maize, Puccinia sorghi.

Effects of temperature on rust development on mint infected with strains of Puccinia menthae

Two principal groups of races of Puccinia menthae occur on mint. One infects native spearmint but not peppermint and is called native spearmint rust; the other infects peppermint but not native spearmint and is called peppermint rust. High summer temperatures are thought to be a limiting factor for rust development on peppermint. The effects of temperature on germination of urediniospores and length of germ tubes of native spearmint and peppermint rust isolates, and on length of latent period when host species were infected with respective isolates, were determined. Percent spore germination and length of germ tubes were significantly greater for the native spearmint isolate than the peppermint isolates; development of both types of rust isolates significantly decreased as temperature increased from 18° to 30 °C. Regression coefficients did not differ between the two types of rust for either percent germination or length of germ tubes. Length of latent period did not differ between isolates of native spearmint and peppermint rust at 18 °C and 23 °C, but latent period was significantly shorter for the native spearmint isolate than peppermint isolates at 28 °C. The increased germination, growth of germ tubes and shorter latent period for native spearmint isolates infecting native spearmint would favour the rust development in relatively warm environments. Conversely, peppermint rust would be disfavoured in increasingly warm environments, further explaining its limitation in high temperature environments.

Inhibition of conidiophore development in Aspergillus fumigatus by an Escherichia coli DH5α strain, a promising antifungal candidate against aspergillosis

The opportunistic human pathogen Aspergillus fumigatus produces a massive number of asexual spores (conidia) as the primary means of dispersal, survival, genome protection and infection of hosts. In this report, we investigated secretory and cytosolic proteins of non-pathogenic bacterial species (mostly belonging to human microbiome) for antifungal potential against A. fumigatus, A. flavus and A. niger. Our preliminary results revealed that cytosolic proteins of E. coli DH5α were most active and the less toxic against various pathogenic isolates of A. fumigatus (the major pathogenic species), depicting a minimum inhibitory concentration (MIC) of 62.50 μg/mL, 62.50 μg/mL and 12.50 μg/disc using microbroth dilution assay (MDA), percentage spore germination inhibition assay (PSGI) and disc diffusion assay (DDA), respectively. E. coli protein was non-toxic against human erythrocytes at doses up to 1000 μg/mL as compared to standard drug, amphotericin B which lysed 100% of erythrocytes at a concentration of 37.50 μg/mL. Time kill analysis proved it to be fungicidal in a concentration and time-dependent manner. Scanning electron microscopic studies (SEM) were carried out to prevail what kind of damage it causes to A. fumigatus. SEM results reported that conidiophore (structures forming conidia) development was halted as a major consequence, reducing the number of conidiophores to insignificant values as well as alteration in their morphological attributes. This feature may contribute to the development of new prevention strategies against Aspergillus infections. Hyphal atrophy was also observed, evidenced by shrinking and flattening of hyphal walls and reduced, abrupt hyphal branching. Such actions may effectively reduce the invasive ability of Aspergillus as well as it can sterilize the fungal burden by obstructing the conidiation pathway of A. fumigatus. Hence, E. coli DH5α, being a commensal species, can lead to the development of antifungal molecule with novel targets in fungal metabolism, which will help in combating the antifungal resistance and toxicity associated with current therapy.

Spore germination of eight homosporous ferns in a temperature gradient

Temperature determines the germination percentage and germination rate of non-dormant fern spores and is known to be a crucial factor for breaking or inducing dormancy in seeds. The objective of this study was to determine the effect of optimal, supraoptimal and suboptimal temperatures on spore germination of eight species of terrestrial homosporous ferns. Spores were incubated for one month in a temperature gradient from 15 to 35°C in either light or dark. Thereafter, the spores were transferred to 25°C and incubated in the light. The optimal temperature for germination varied among species, and germination inhibition and possible secondary dormancy were induced at both suboptimal and supraoptimal temperatures. At 35 or 30°C, with light, spores of most species did not germinate or exhibited low germination percentages, owing to thermoinhibition or possible thermodormancy. In the dark, the spores did not germinate at any of the temperatures tested. After the spores were transferred to the light at 25°C, a high percentage of spore germination was observed. Incubation in the dark at different temperatures also promoted high germination or dormancy. Temperatures that promoted germination might be related to the season that the different species germinate rather than their habitat, as a number of species within the same habitat had different optimum temperature requirements. Differences in temperature requirements may help to form a soil spore bank. It is necessary to determine whether secondary dormancy was induced by supraoptimal and suboptimal temperatures to further understand spore germination and colonisation in the field.

Composition and structure of arbuscular-mycorrhizal communities in El Palmar National Park, Argentina

The arbuscular-mycorrhizal-fungal (AMF) communities from the El Palmar National Park of Entre Ríos Province, Argentina, were investigated and characterized. The species of AMF present in five distinct vegetation types—gallery forest, grassland, marsh, palm forest, and scrubland—were isolated, identified and quantified over 2 y. Forty-six AMF morphotaxa were found. The composition of the AMF communities differed between the seasons, soil and vegetation types. Seasonal variations were observed in members of the Acaulosporaceae, Archaeosporaceae, Claroideoglomeraceae, Gigasporaceae and Pacisporaceae. Depending on soil type, the AMF-spore communities were dominated by members of one of the two main orders of the Glomeromycota. AMF communities from grassland and palm forest, which occur on sandy soils, comprised primarily members of the Diversisporales, with a high percentage of species of Acaulospora and of Gigasporaceae. Communities from the gallery forest, marsh and scrubland, which occur on loam-clay soils, were composed of members of the Glomerales, with a high percentage of spores from species of Glomus. Thus, both AMF and plant communities would appear to be strongly and similarly influenced by edaphic conditions.