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1.
The spectrum of entomophthoroid fungal species parasitising aphids on cereal crops and a study of the phenology and prevalence of these pathogens were investigated in Argentina. The studies were conducted at six different sites cultivated with crops of Triticum aestivum (wheat), Avena sativa (oats) and Sorghum bicolor (sorghum) during two consecutive years. Entomopathogenic fungi from the new phylum Entomophthoromycota were recorded from six aphid species on cereals in Argentina: Rhopalosiphum maidis, Rhopalosiphum padi, Rhopalosiphum rufiabdominalis, Schizaphis graminum, Sitobion avenae and Sipha maydis. Three species of entomophthoroid fungi were found infecting these aphid species: Pandora neoaphidis, Zoophthora radicans (Entomophthorales: Entomophthoraceae) and Neozygites fresenii (Neozygitales: Neozygitaceae). Entomophthoroid fungal infections occurred mostly in autumn–winter seasons (March–August), and coincided with periods of high relative humidity and comparatively low temperatures. This study represents the first base‐line characterisation of entomophthoroid fungi infecting aphids on cereal crops in Argentina.  相似文献   

2.
Argemone mexicana L. (Papaveraceae), a tropical annual weed, is known to be phytotoxic to many crop species. This study was designed to examine the possible impact of A. mexicana on root‐infecting fungi, changes in fungal community structure and the growth of tomato. A. mexicana decaying shoots in soil provided a marked decrease in the infectivity of Fusarium solani and Rhizoctonia solani but Macrophomina phaseolina remained unaffected. Plant height and shoot growth of tomato plants increased markedly though high concentration of A. mexicana (5% w/w) was deleterious to tomato plants. General species diversity of soil fungal communities increased in the amended soils over the controls and greater increase in diversity occurred at higher concentrations of decaying A. mexicana. Likewise, equitability and richness components of diversity increased in treatments compared to controls but declined with increasing sampling period. Aspergillus nidulans, Cephaliophora irregularis, Drechslera halodes, Paecilomyces lilacinus and Trichoderma viride were isolated exclusively from the amended soils. Aqueous extract of A. mexicana when applied in soil greatly suppressed all three of the above root‐infecting fungi, and at lower concentration actually enhanced plant growth. The influence of different levels of N‐fertilization with NH4NO3 on the modification of the effect of decaying A. mexicana on root‐infecting fungi was also investigated. N‐fertilization to some extent alleviated the phytotoxicity to tomato plants while suppressing the root‐infecting fungi. A. mexicana in conjunction with Pseudomonas aeruginosa, a plant growth‐promoting rhizobacterium, significantly suppressed root‐infecting fungi with concomitant increase in plant growth. Whereas P. aeruginosa was reisolated from the rhizosphere and inner root tissues of tomato, its population slightly declined in the amended soil but not to an extent that could reduce the biocontrol and growth promoting potential of the bacterium.  相似文献   

3.
A new species of rodent of the genus Phyllotis is described based in cranial and external morphology, as well as morphometric data. Additionally, sequences of the mitochondrial gene cytochrome-b were used to asses the phylogenetic relationships. We have compared our specimens with all the extant species of the genus Phyllotis and also with some species of related genera, particularly with the most similar and with those that occur in the province of Tucumán and northwestern Argentina. The new species is large compared to the average size of the genus, and can be easily distinguished from all other species essentially by coloration and by cranial morphology. It is closely related to the recently described P. anitae, and these two species are, in turn, sister to P. osilae. The only two localities where the new species has been found are in the Upper Montane Forests of the southern portion of the Yungas Ecoregion, in the province of Tucumán, Argentina.  相似文献   

4.
Propolis samples from north‐west Argentina (Amaicha del Valle, Tucumán) were evaluated by palynology, FT‐IR spectra, and RP‐HPTLC. In addition, the volatile fraction was studied by HS‐SPME‐GC/MS. The botanical species most visited by Apis mellifera L. near the apiaries were collected and their RP‐HPTLC extracts profiles were compared with propolis samples. In addition, GC/MS was performed for volatile compounds from Zuccagnia punctata Cav. (Fabaceae). FT‐IR spectra and RP‐HPTLC fingerprints of propolis samples showed similar profiles. In RP‐HPTLC analyses, only Z. punctata presented a similar fingerprint to Amaicha propolis. The major volatile compounds present in both were trans‐linalool oxide (furanoid), 6‐camphenone, linalool, trans‐pinocarveol, p‐cymen‐8‐ol, and 2,3,6‐trimethylbenzaldehyde. Potential variations for the Amaicha del Valle propolis volatile fraction as consequence of propolis sample preparation were demonstrated.  相似文献   

5.
Variations in the chemical composition of the essential oils of Minthostachys mollis Griseb. (Lamiaceae) collected in their natural habitat in Argentina were determined using GC-FID-MS analysis. Seventy five samples collected out of 40 wild plant populations in the Central and Northwestern Argentina during four years sampling, were analyzed. Principal Component Analysis was made on the chemical data showing that samples from Córdoba and San Luis belonged to the typical menthone – pulegone chemotype in accordance with previous reports; meanwhile samples from Tucumán, Salta and Catamarca showed the presence of different compositions, some previously unreported, mainly those detected in Tucumán province. In addition, cluster analysis was applied using Euclidean distance to measure the dissimilarity in the relative composition of samples from Tucumán, Salta and Catamarca, using Ward's method as the agglomeration technique. Five groups were retained with less than 10% of information loss: i) dihydrocarvone-carvone, ii) pulegone with absence of menthone, iii) carvacryl acetate-carvacrol, iv) limonene and v) linalool.It is worth mentioning that the compositions of the different chemotypes remained constant throughout the four years of collection and despite the highly diverse pattern of compositions revealed in this search, the typical chemotype was not found present northwards Córdoba and San Luis provinces. This is the first report of a deep study on natural populations of peperina throughout the whole distribution area in Argentina with consecutive sampling repetitions of the same populations during several years.  相似文献   

6.
Fibrinolytic enzyme production was evaluated in fungal specimens isolated from the sub-tropical Las Yungas Pedemontana forest (Tucumán, Argentina). Proteolytic and fibrinolytic activities were evaluated in freeze-thaw crude extracts from 230 fungal isolates on 1% w/v skimmed-milk or 0.25% w/v fibrin-agar plates, respectively. Proteolytic activity was positive in 62% of the isolates, whilst only three of them were able to produce extracellular fibrinolytic enzymes on solid nutritive medium. Fibrinolytic-positive extracts were able to degrade fibrin clots in a direct plasminogen-independent way. Selected isolates were identified by sequencing the 26S rDNA D1/D2 domain. Isolates LY 4.1 and LY 4.4 showed a 99.9% similarity with Bionectria ochroleuca, while LY 4.2 showed a 99.9% identity with Cladosporium cladosporioides. Under submerged culture conditions, LY 4.1 and LY 4.4 were able to excrete fibrinolytic enzymes, reaching a maximum at 120 h of cultivation of 100.2 and 107.9 U/ml in plasmin-equivalent units, respectively. Fibrinolytic enzyme production could be scaled-up to fermenter scale reaching similar values. Fibrin zymography showed that fibrinolytic activity was associated with ~173-, 153- and 80-kDa protein fractions. Extracellular fibrinolytic enzymes from Bionectria species may be potentially related to pathogenesis mechanisms, as already demonstrated for serine-proteases from the nematicidal anamorph Clonostachys rosea. This work reveals the potential of Bionectria strains as an unconventional and unexplored production alternative to already known thrombolytic agents. The value of Las Yungas forests as a reservoir of fungal species with promising biotechnological value could be also highlighted.  相似文献   

7.
A plant growth‐promoting rhizobacterium, Pseudomonas aeruginosa strain IE‐6, and a fungal antagonist, Pochonia chlamydosporia, were tested for their ability to inhibit mycelial growth of root‐infecting fungi under laboratory conditions including Macrophomina phaseolina, Fusarium oxysporum, F. solani and Rhizoctonia solani. Biocontrol effectiveness of the bacterium and the fungus alone or in combination was also determined for the control of root‐infecting fungi under field conditions. In a dual‐culture plate assay, the colonies of P. chlamydosporia and P. aeruginosa met each other and no further growth of either organism occurred. Against M. phaseolina, F. solani and R. solani, an ethyl acetate extract of the culture filtrates of P. aeruginosa inhibited fungal growth greater than the hexane extract, but against F. oxysporum the hexane extract caused greater inhibition of fungal growth. By contrast, against M. phaseolina, F. oxysporum and F. solani, the hexane extract of P. chlamydosporia was more effective in the inhibition of fungal growth than the ethyl acetate fraction. Ethyl acetate extracts of P. aeruginosa at 1.0 mg/ml not only inhibited the radial colony growth of R. solani but also lysed the fungal mycelium. P. aeruginosa produced siderophores and hydrogen cyanide under laboratory conditions. Field experiments conducted in 1997 and repeated in 1998 revealed that Pochonia chlamydosporia and P. aeruginosa significantly suppressed the root‐infecting fungi M. phaseolina, F. oxysporum, F. solani and R. solani and that the combination of the two caused greater inhibition of the fungal pathogens than either alone. Application of P. chlamydosporia and P. aeruginosa as a soil drench also resulted in enhanced growth of tomato plants.  相似文献   

8.
Recent studies have detected phylogenetic signals in pathogen–host networks for both soil‐borne and leaf‐infecting fungi, suggesting that pathogenic fungi may track or coevolve with their preferred hosts. However, a phylogenetically concordant relationship between multiple hosts and multiple fungi in has rarely been investigated. Using next‐generation high‐throughput DNA sequencing techniques, we analyzed fungal taxa associated with diseased leaves, rotten seeds, and infected seedlings of subtropical trees. We compared the topologies of the phylogenetic trees of the soil and foliar fungi based on the internal transcribed spacer (ITS) region with the phylogeny of host tree species based on matK, rbcL, atpB, and 5.8S genes. We identified 37 foliar and 103 soil pathogenic fungi belonging to the Ascomycota and Basidiomycota phyla and detected significantly nonrandom host–fungus combinations, which clustered on both the fungus phylogeny and the host phylogeny. The explicit evidence of congruent phylogenies between tree hosts and their potential fungal pathogens suggests either diffuse coevolution among the plant–fungal interaction networks or that the distribution of fungal species tracked spatially associated hosts with phylogenetically conserved traits and habitat preferences. Phylogenetic conservatism in plant–fungal interactions within a local community promotes host and parasite specificity, which is integral to the important role of fungi in promoting species coexistence and maintaining biodiversity of forest communities.  相似文献   

9.
The first record of Cavia tschudi Fitzinger, 1857 for the subandean area of Salta Province, Argentina, is herein presented.

This species presently inhabits the subandean area of the provinces of Tucumán and Jujuy. The materials are composed of two mandibles coming from an archaeological site, which had been occupied ca. 1480 AD, at 2300 m a.s.l.  相似文献   

10.
Yellows diseases associated with phytoplasmas cause high mortality in China‐tree (Melia azedarach) in Argentina, but there has been no previous large‐scale survey to determine their diversity and geographical distribution. To assess the presence and identity of phytoplasmas affecting this species throughout the country, 425 samples of symptomatic trees collected at different geographic locations were analysed by a polymerase chain reaction (using universal and group‐specific primers) and restriction fragment length polymorphism. Phytoplasmas belonging to 16SrIII‐B group were detected at almost every location sampled, whereas 16SrXIII‐C group phytoplasmas, reported for the first time in Argentina, were only found in two regions sharing similar agro‐ecological characteristics (Northeast provinces and Tucumán). Double infections with 16SrIII‐B and 16SrXIII‐C group phytoplasmas were also recorded. Nucleotide sequencing of the 16S rDNA of three Argentinian 16SrXIII‐C group phytoplasma isolates revealed high identity (99.6–99.3%) with the CbY1 isolate reported from Bolivia.  相似文献   

11.
The diversity of arbuscular mycorrhizal (AM) fungi and their broad or narrow association with distinct plant species in natural environments are crucial information in the understanding of the ecological role of AM fungi on plant co-existence. This knowledge is also needed for appropriate mycorrhization of nursery-grown seedlings for forestation efforts. Here, we report results from comparative studies on three co-occurring indigenous tree species of the dry Afromontane forests of Ethiopia and their seedlings grown under controlled conditions in soil collected from the sites. AM fungal SSU rDNA fragment was amplified and sequenced from mycorrhizas of adult plants and seedlings of Olea europaea subsp. cuspidata and Prunus africana, and from Podocarpus falcatus seedlings. AM fungal identity, diversity and community structure were analyzed based on sequence types defined by the NS31-AM1 SSU rDNA fragment similarity in order to compare with data from other habitats. A total of 409 sequences, grouped in 32 sequence types, belonging to Glomeraceae, Diversisporaceae and Gigasporaceae were found. Some sequence types are close to the widespread Glomus intraradices, G. hoi, G. etunicatum, G. cf. etunicatum and Gigaspora margarita. However, the majority (59%) of sequence types are so far specific for the sites including 11 new types when compared with previous data from the same area. The AM fungal community associated with adult plants, including data previously obtained from adult Podocarpus falcatus seedlings, and seedlings of a host species differed significantly, where seedlings trapping a surprising large number of native fungi. AM fungal community structure also differed significantly between host species and sites, respectively. The results confirm previous results from the same area indicating distinct fungal communities associated with the diverse tree species and suggests the potential of these indigenous tree seedlings to trap a wide range of AM fungi appropriate for successful afforestation.  相似文献   

12.
Azospirillum species are free-living nitrogen-fixing bacteria commonly found in soil and in association with roots of different plant species. For their capacity to stimulate growth they are known as plant growth-promoting bacteria (PGPB). In this work, we demonstrate the natural occurrence and colonization of different parts of strawberry plants by Azospirillum brasilense in the cropping area of Tucumán, Argentina. Although bacteria isolations were carried out from two strawberry cultivars, e.g., Camarosa and Pájaro, attempts were successful only with the cultivar Camarosa. Whereas different strains of Azospirillum were isolated from the root surface and inner tissues of roots and stolons of the cultivar Camarosa, we have not obtained Azospirillum isolates from the cultivar Pájaro. After microbiological and molecular characterization (ARDRA) we determined that the isolates belonged to the species A. brasilense. All isolates showed to have the capacity to fix nitrogen, to produce siderophores and indoles. Local isolates exhibited different yields of indoles production when growing in N-free NFb semisolid media supplemented or not with tryptophan (0.1 mg ml−1). This is the first report on the natural occurrence of A. brasilense in strawberry plants, especially colonizing inner tissues of stolons, as well as roots. The local isolates showed three important characteristics within the PGPB group: N2-fixation, siderophores, and indoles production.  相似文献   

13.
En el curso de las investigaciones sobre la fauna de las aguas subterráneas límnicas de la Argentina, se encontraron en pocas muestras una sorprendente cantidad de especies de crustáceos.

Una de las especies (Leptobathynella richerti) fué descubierta poco antes en Paraguay y 3 especies (Parastygocaris goerssi, P. andina e Ingolfiella uspallatae) ya han sido publicadas por el autor. Aqui se describen, se ilustran y se discuten 2 especies del género Parabathynella, 1 Nitocrella y 12 Parastenocaris como nuevas para la ciencia. Se completa la descripción de Leptobathynella richerti. Por falta de material, otras 5 especies aún no se han podido determinar.

Por consiguiente, la fauna de las aguas subterráneas neotropicales prueba ser abun‐dante y representada por mudias especies también en la Argentina. Un análisis biogeo‐gráfico del material aparecerá en otra oportunidad con relaciones más ámplias.

Las investigaciones serán continuadas.  相似文献   

14.
RNA silencing is an ancient regulatory mechanism operating in all eukaryotic cells. In fungi, it was first discovered in Neurospora crassa, although its potential as a defence mechanism against mycoviruses was first reported in Cryphonectria parasitica and, later, in several fungal species. There is little evidence of the antiviral potential of RNA silencing in the phytopathogenic species of the fungal genus Botrytis. Moreover, little is known about the RNA silencing components in these fungi, although the analysis of public genome databases identified two Dicer‐like genes in B. cinerea, as in most of the ascomycetes sequenced to date. In this work, we used deep sequencing to study the virus‐derived small RNA (vsiRNA) populations from different mycoviruses infecting field isolates of Botrytis spp. The mycoviruses under study belong to different genera and species, and have different types of genome [double‐stranded RNA (dsRNA), (+)single‐stranded RNA (ssRNA) and (–)ssRNA]. In general, vsiRNAs derived from mycoviruses are mostly of 21, 20 and 22 nucleotides in length, possess sense or antisense orientation, either in a similar ratio or with a predominance of sense polarity depending on the virus species, have predominantly U at their 5′ end, and are unevenly distributed along the viral genome, showing conspicuous hotspots of vsiRNA accumulation. These characteristics reveal striking similarities with vsiRNAs produced by plant viruses, suggesting similar pathways of viral targeting in plants and fungi. We have shown that the fungal RNA silencing machinery acts against the mycoviruses used in this work in a similar manner independent of their viral or fungal origin.  相似文献   

15.
Two new species of Farrodes Peters are described. These new species are the first records of Farrodes from continental South America and Argentina, and represent a southward range extension of roughly 4.500 km. Both primary faunal components of Neotropical Leptophlebiidae are present in the north‐argentinean province of Tucuman (27° S). However, these two faunal components are geographically separated along a temperature‐elevation gradient. Farrodes and Thraulodes Ulmer of the Guiana & Brazilian Shields, Warm‐Adapted Genera are common in streams at elevations below 1,550 m. In contrast, the leptophlebiid fauna at elevations above 2,000 m is composed entirely of Patagonian Shield, South Andean, Cold‐Adapted Genera with Meridialaris Peters & Edmunds and Massartellopsis Demoulin being particularly abundant. Streams between 1,550–2,000 m in Tucumán Province remain uncollected and the elevation and conditions at which faunal mixing or replacement occurs remain unknown.  相似文献   

16.
In terrestrial ecosystems, plant roots are colonized by various clades of mycorrhizal and endophytic fungi. Focused on the root systems of an oak‐dominated temperate forest in Japan, we used 454 pyrosequencing to explore how phylogenetically diverse fungi constitute an ecological community of multiple ecotypes. In total, 345 operational taxonomic units (OTUs) of fungi were found from 159 terminal‐root samples from 12 plant species occurring in the forest. Due to the dominance of an oak species (Quercus serrata), diverse ectomycorrhizal clades such as Russula, Lactarius, Cortinarius, Tomentella, Amanita, Boletus, and Cenococcum were observed. Unexpectedly, the root‐associated fungal community was dominated by root‐endophytic ascomycetes in Helotiales, Chaetothyriales, and Rhytismatales. Overall, 55.3% of root samples were colonized by both the commonly observed ascomycetes and ectomycorrhizal fungi; 75.0% of the root samples of the dominant Q. serrata were so cocolonized. Overall, this study revealed that root‐associated fungal communities of oak‐dominated temperate forests were dominated not only by ectomycorrhizal fungi but also by diverse root endophytes and that potential ecological interactions between the two ecotypes may be important to understand the complex assembly processes of belowground fungal communities.  相似文献   

17.
Five native species of the flora of Egypt: Adonis dentata Delile, Ranunculaceae; Papaver dubium L., Papaveraceae; Matthiola longipetala (Vent.) DC., Brassicaceae; Malva parviflora L., Malvaceae; and Erodium laciniatum (Cav.) Willd., Geraniaceae have been investigated morphologically, palynologically and mycologically. The total counts of phyllosphere fungi fluctuated between 223 and 388 colonies/100 leaf segments giving maximum on Malva parviflora followed by Matthiola longipetala, Erodium laciniatum, Papaver dubium and Adonis dentata. The widest spectrum of genera (20) and species (39 and l variety) was recorded on Malva parviflora and the narrowest on Adonis dentata (9, 14). Sixty species and one variety belonging to 27 genera were collected from leaves (24 genera and 56 species and 1 variety) and anthers/pollen (16 genera and 27 species) of the five studied plants with the most frequently species were some members of Alternaria, Cladosporium, Fusarium and Mucor. Members of Aspergillus and Penicillium were prevalent only on leaves of Matthiola longipetala and Malva parviflora, while these members were infrequently recorded on leaf surfaces of Adonis dentata and Papaver dubium. Results revealed that density of hairs on the leaf surface and size of leaf blade, almost seem to be the most reliable factors of the biodiversity of the fungal spores on the studied taxa. On the other hand, reticulate or striate pollen surface had a wider spectrum of fungal biodiversity and higher densities of spores compared with echinate and scabrate surface.  相似文献   

18.
The distribution of entomopathogenic fungi in various geographical areas of Punjab, Pakistan, is poorly understood. The present study was planned to explore the occurrence and diversity of entomopathogenic fungi from soils collected from cultivated and non‐cultivated habitats. The detailed survey of different habitats (crop fields, fruits, vegetables, forests) was conducted to collect soil samples and the associated fungi were isolated using Galleria bait method. Among 210 soil samples, 168 fungal isolates were recovered and identified, with 98 from forests, 32 from vegetables, 30 from field crops and 8 from fruits. The major entomopathogenic fungi recovered from these samples were Beauveria bassiana, Metarhizium anisopliae, Paecilomyces lilacinus, B. brongniartii, P. chlamydosporia and Lecanicillium attenuatum. The diversity of entomopathogenic fungi was greater in soil samples from forests compared to crop fields, vegetables and fruits, respectively. The geographical attributes (altitude, longitude, latitude) greatly influenced the occurrence of entomopathogenic fungi with the highest number of isolates found from >600 m altitude, 33°–34′N latitude, and 73°74′E longitude from soil samples. The results of the surveys clearly indicated that the entomopathogenic fungi are distributed in the soils which may be used in successful IPM programs in future.  相似文献   

19.
Xing YM  Chen J  Cui JL  Chen XM  Guo SX 《Current microbiology》2011,62(4):1218-1224
Endophytic fungi are rich in orchids and have great impacts on their host plants. 53 endophytes (30 isolates from Dendrobium devonianum and 23 endophytic fungi from D. thyrsiflorum) were isolated, respectively, from roots and stems of Dendrobium species. All the fungi were identified by way of morphological and/or molecular biological methods. 30 endophytic fungi in D. devonianum were categorized into 11 taxa and 23 fungal endophytes in D. thyrsiflorum were grouped into 11 genera, respectively. Fusarium was the dominant species of the two Dendrobium species in common. Antimicrobial activity of ethanol extract of fermentation broth of these fungi was explored using agar diffusion test. 10 endophytic fungi in D. devonianum and 11 in D. thyrsiflorum exhibited antimicrobial activity against at least one pathogenic bacterium or fungus among 6 pathogenic microbes (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus). Out of the fungal endophytes isolated from D. devonianum and D. thyrsiflorum, Phoma displayed strong inhibitory activity (inhibition zones in diameter >20 mm) against pathogens. Epicoccum nigrum from D. thyrsiflorum exhibited antibacterial activity even stronger than ampicillin sodium. Fusarium isolated from the two Dendrobium species was effective against the pathogenic bacterial as well as fungal pathogens. The study reinforced the assumption that endophytic fungi isolated from different Dendrobium species could be of potential antibacterial or antifungal resource.  相似文献   

20.
S. M. Ovruski 《BioControl》1995,40(3-4):367-370
Pupal and larval-pupal parasitoids were obtained from 5 % of the 1,413 tephritid puparia collected in four localities of the Tucumán province, Argentina, from April, 1991 to April, 1993.Ceratitis capitata (Wiedemann) was attacked byPachycrepoideus vindemmiae (Rondani) (Pteromalidae), a pupal parasitoid, andAganaspis pelleranoi (Brèthes) (Eucoilidae), a larval parasitoid.Anastrepha spp. were attacked byDoryctobracon areolatus (Szépligeti) (Braconidae), a larval parasitoid, and also byA. pelleranoi. Information about parasitism, percentage of emergence of tephritid species and pupal viability in different localities is provided.  相似文献   

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