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PubMed2003

Isolation and anti-oomycete activity of nyasol from Anemarrhena asphodeloides rhizomes.

The methanol extract of Anemarrhena asphodeloides rhizomes exhibited strong antifungal activity against the plant pathogenic fungi Magnaphothe grisea, Rhizoctonia solani, and the plant pathogenic oomycete Phytophthora capsici. The antifungal substance isolated from the rhizomes of A. asphodeloides was identified to be nyasol, (Z)-1,3-bis(4-hydroxyphenyl)-1,4-pentadiene by NMR and mass spectral analysis. Nyasol effectively inhibited the mycelial growth of Colletotrichum orbiculare, P. capsici, Pythium ultimum, R. solani, and Cladosporium cucumerinum in a range of 1-50 mug/ml, but did not affect the growth of bacteria and yeast. In a greenhouse test, treatment with the antifungal compound nyasol was significantly effective in suppressing the Phytophthora blight on pepper plants.

Alanine↗

PubMed2003

Three types of immunotherapics against pythiosis insidiosi developed and evaluated.

Pythiosis is a granulomatous disease of horses, cattle, dogs, cats and humans identified in tropical and subtropical areas and caused by Pythium insidiosum, a zoosporic fungus. Experimental models of pythiosis in naturally infected species have not yet been reported but, rabbits may be inoculated with zoospores as an experimental model for studying the disease. The present study evaluates the efficacy of three different of immunotherapics in the rabbit model. Approximately 17500 zoospores of oomycete P. insidiosum (CBS 101555 strain) were inoculated in each animal to generate the disease. Immunotherapics were produced from vortexed or sonicated cultures of the same strain. Four groups of five animals were employed: group 1, placebo; group 2, sonicated immunotherapic; group 3, mixed immunotherapic; and group 4, vortexed immunotherapic. All rabbits were inoculated with viable zoospores one month before administration of the immunotherapics. Eight doses of immunotherapic or placebo were used in each animal with a 14 day interval between injections. Rabbits receiving the vortexed immunotherapic were most effectively protected (P<0.05), showing a decrease in the area of coastal nodules due to Pythiosis insidiosum by 71.8% after 26 weeks of evaluation. Moreover, two animals in this group showed complete remission of the infection at the end of the 26 weeks. In contrast to these findings, rabbits given the sonicated immunotherapic did not show any protection and had an increase of 211.8% in the size of lesions. This failure of sonicated immunotherapic may reflect denaturation of protective antigens due to the sonication method.

Animals↗

PubMed2003

Chemical composition and antifungal properties of essential oils of three Pistacia species.

The chemical composition of essential oils obtained from the leaves of Pistacia vera, Pistacia terebinthus, Pistacia lentiscus and the resin of Pistacia lentiscus were analyzed by GC and GC-MS. alpha-Pinene, beta-pinene, limonene, terpinen-4-ol and alpha-terpineol were found to be the major components. The antifungal activities of the above oils and P. lentiscus resin (total, acidic and neutral fractions) against the growth of three agricultural pathogens, Pythium ultimum, Rhizoctonia solani and Fusarium sambucinum were evaluated. Some doses of P. terebinthus, P. vera and P. lentiscus leaf oils and total and neutral fraction of P. lentiscus resin significantly inhibited the growth of R. solani. However, all samples did not show antifungal activity against P. ultimum and F. sambucinum, but increased the growth of F. sambucinum.

Antifungal Agents↗

PubMed1999

Resistance to oomycetes: a general role for the hypersensitive response?

Oomycete plant pathogens, such as Phytophthora, downy mildews and Pythium, have devastating disease effects on numerous crop and ornamental plants. Various types of genetic resistance to oomycetes occur in plants, and can be determined at the subspecific or varietal level (race or cultivar-specific resistance), or at the species or genus level (nonhost resistance). In addition, resistance might be a quantitative phenotype (partial resistance). Resistance reactions are often associated with the hypersensitive response - a programed cell death pathway. Recent advances in the genetic, biochemical and cytological characterization of disease resistance suggests that the hypersensitive response is associated with all forms of resistance to Phytophthora and downy mildews. Identification of the resistance genes involved in nonhost and partial resistance to oomycetes remains an important challenge.

Journal Article↗

PubMed2004

Effects of the fermentation product of herbs by lactic acid bacteria against phytopathogenic filamentous fungi and on the growth of host plants.

The fermentation product of herbs by lactic acid bacteria (FHL) was assayed for antifungal activities against Rosellinia necatrix, Helicobasidium mompa, Fusarium oxysporum, Pythium graminicola and Pyricularia oryzae. FHL completely inhibited the growth of R. necatrix, H. mompa, P. graminicola and P. oryzae, and reduced the growth of F. oxysporum by 35%. When the seeds of Medicago sativa L. (alfalfa), Asparagus officinalis L. (asparagus), Brassica campestris L. (komatsuna), Oryza sativa L. (rice), Spinacia oleracea L. (spinach), Festuca arundinacea Schreb. (tall fescue), and Lycopersicum esculentum Mill. (tomato) were put on plates containing 0.69 mg/ml FHL, their germination rates did not decrease. The root elongation of A. officinalis, B. campestris, O. sativa, and L. esculentum seedlings was suppressed on plates containing 6.92 mg/ml FHL, but the root elongation of M. sativa was not suppressed on the 6.92 mg/ml FHL plate. When FHL was diluted to less than 1.73 mg/ml, the diluted FHL solution did not suppress the germination of B. campestris seeds, but it suppressed the root elongation of B. campestris seedlings. An FHL concentration higher than 0.35 mg/ml hastened the growth of seedlings of B. campestris in the presence of a chemical fertilizer but delayed the growth of these seedlings in the absence of the chemical fertilizer, suggesting that inorganic elements could affect the efficiency of FHL.

Journal Article↗

PubMed2003

Phylogenetic relationships of Peronospora and related genera based on nuclear ribosomal ITS sequences.

In order to investigate phylogenetic relationships of selected members of Peronosporaceae to the genera Pythium, Halophkytophthora, Phytophthora, and Peronophythora, Bayesian analysis of partial sequences of the ITS1-5.8S-ITS2 region was performed. In addition, sequences of the complete ITS1-5.8S-ITS2 region were analysed for 101 collections belonging to the genera Peronospora, Hyaloperonospora, Perofascia, Pseudoperonospora, Phytophthora and Peronophythora, using Bayesian inference of phylogeny and maximum parsimony. The results confirm a close relationship of these genera. The strongly supported Peronosporaceae clade is located within the paraphyletic genus Phytophthora (including Peronophythora). Monophyly of the genera Pseudoperonospora and Hyaloperonospora are strongly supported, but monophyly of Peronospora s. str. can neither be confirmed nor rejected. Within Peronospora s. str., basic relationships often remain unclear; however, some groups form highly supported monophyletic clades. Peronospora species parasitising the same host families or orders are only partly resolved as monophyletic, indicating frequent host-jumping also between distantly related host families. All species inhabiting flowers of different host families form a strongly supported monophyletic group.

Base Sequence↗

PubMed2004

Antifungal activity of beta-asarone from rhizomes of Acorus gramineus.

An antifungal substance was isolated from the extract of Acorus gramineus using various chromatographic procedures. The antibiotic was identified as beta-asarone, cis-2,4,5-trimethoxy-1-propenylbenzene, on the basis of the high-resolution EI-mass, NMR, and UV spectral data. Beta-asarone completely inhibited mycelial growth of some plant pathogenic fungi, Cladosporium cucumerinum,Colletotrichum orbiculare, Magnaporthe grisea, and Pythium ultimum, in a range of 0.5-30 microg/mL. The growth of Bacillus subtilis, Erwinia carotovora subsp. carotovora, Ralstonia solanacearum, and Xanthomonas campestris pv. vesicatoria was slightly suppressed by beta-asarone. As the concentration of beta-asarone increased, M. grisea infection was drastically inhibited on rice leaves. Treatment with 500 microg/mL of beta-asarone also greatly suppressed lesion formation of Co. orbiculare on cucumber leaves. This is the first study to demonstrate in vitro and in vivo antifungal activity of beta-asarone against plant fungal pathogens M. grisea and C. orbiculare.

Acorus↗

PubMed2005

Synthesis and fungicidal activity of novel 2-oxocycloalkylsulfonylureas.

A series of 2-oxocycloalkylsulfonylureas (2) have been synthesized in a six-step, three-pot reaction sequence from readily available cyclododecanone, cycloheptanone, and cyclohexanone. Their structures were confirmed by IR, 1H NMR, and elemental analysis. The bioassay indicated that some of them possess certain fungicidal activity against Gibberella zeae Petch. In general, compounds containing a 12-membered ring (2A) are more active than those containing a 6- or 7-membered ring (2B, 2C). In the series 2A, the compounds in which R is a disubstituted phenyl or pyrimidyl showed better activity than those in which R is a monosubstituted phenyl or pyrimidyl, and aryl-substituted compounds have somewhat higher activity than those substituted by pyrimidyl. The further bioassay showed that the representative of 2A, 2A15, has good fungicidal activities against not only G. zeae Petch but also Botrytis cinerea Pers, Colletotrichum orbiculare Arx, Pythium aphanidermatum Fitzp, Fusarium oxysporum Schl. f. sp. Vasinfectum, etc.

Fungi↗

PubMed2005

Isolation and antifungal activity of 4-phenyl-3-butenoic acid from Streptomyces koyangensis strain VK-A60.

An antifungal compound was isolated from the culture broth of Streptomyces koyangensis strain VK-A60 using various chromatographic procedures. On the basis of the high-resolution EI-mass and 1H and 13C NMR data, the compound was identified as 4-phenyl-3-butenoic acid. Colletotrichum orbiculare, Magnaporthe grisea, and Pythium ultimum were most sensitive to 4-phenyl-3-butenoic acid. Strong inhibitory effects of 4-phenyl-3-butenoic acid also were found against Pectobacterium carotovorum subsp. carotovorum and Ralstonia solanacearum. 4-Phenyl-3-butenoic acid effectively suppressed the development of M. grisea on rice leaves at the concentration of more than 10 microg/mL, and the protective activity was in general similar to that of the commercial fungicide tricyclazole. Treatment with 100 microg/mL of 4-phenyl-3-butenoic acid also effectively inhibited the anthracnose development on cucumber plants, although its in vivo efficacy was somewhat less effective than that of the commercial fungicide chlorothalonil.

Culture Media, Conditioned↗

PubMedDate not supplied

Faeriefungin: a new broad-spectrum antibiotic from Streptomyces griseus var. autotrophicus.

Faeriefungin, a polyol polyene macrolide lactone antibiotic, was isolated from the mycelium of Streptomyces griseus var. autotrophicus, MSU-32058/ATCC 53668, collected from the soil sample of a fairy ring in an old lawn in Lansing, Michigan. Faeriefungin has some properties similar to the previously reported polyene macrolides, mycoticin and flavofungin, but possesses different physiochemical and biological properties. Aspergillus, Fusarium, Microsporum, Trichophyton, and Alternaria spp. were completely inhibited by faeriefungin at 3.2 micrograms/ml, Candida spp. at 5.5 micrograms/ml, and Pythium, Phialophora, Leptosphaeria spp., and some selected Gram-negative penicillin-resistant strains of Neisseria gonorrhoeae at 16.0 micrograms/ml. At a concentration of 100 ppm, it caused 100% mortality of mosquito larvae (Aedes aegypti, Rockefeller strain) and free-living nematodes (Panagrellus redivivus). Unlike the related polyene macrolides, faeriefungin is crystalline and stable with broad-spectrum antimicrobial and insecticidal activity. Preliminary cytotoxicity studies with human erythrocytes and rat liver epithelial cells indicated that faeriefungin and amphotericin B have comparable toxicity. Solution nmr study has indicated that faeriefungin is a mixture of two compounds, faerifungins A [1] and B [2], and that they differ in the attachment of a H or an Me at C-33.

Acetylation↗

PubMed2004

Effects of nematicides on cotton root mycobiota.

Baseline information on the diversity and population densities of fungi collected from soil debris and cotton (Gossypium hirsutum L.) roots was determined. Samples were collected from Tifton, GA, and Starkville, MS containing cotton field soil treated with the nematicides 1,3-dichloroproprene (fumigant) and aldicarb (granules). A total of 10,550 and 13,450 fungal isolates were collected from these two study sites, respectively. Of this total, 34 genera of plant pathogenic or saprophytic species were identified. Pathogenic root fungi included Fusarium spp. (40% of all isolations), Macrophomina, Pythium, Rhizoctonia, and Sclerotium. Fusarium and Rhizoctonia were the most common fungal species identified and included F. oxysporum, F. verticillioides and F. solani, the three Fusarium species pathogenic on cotton plants. Population densities of Fusarium were not significantly different among locations or tissue types sampled. Macrophomina was isolated at greater numbers near the end of the growing seasons. Anastomosis groups of R. solani isolated from roots and soil debris included AG-3, -4, -7, 2-2, and -13 and anastomosis groups of binucleate Rhizoctonia included CAG-2, -3, and -5. Occurrences and frequency of isolations among sampling dates were not consistent. Fluctuations in the frequency of isolation of Rhizoctonia did not correspond with changes in frequency of isolation of the biological control fungus, Trichoderma. When individual or pooled frequencies of the mycobiota were compared to nematicide treatments, no specific trends occurred between treatments, application methods or rates. Results from this study show that use of 1,3-D and aldicarb in cotton fields does not significantly impact plant pathogenic fungi or saprophytic fungal populations. Thus cotton producers need not adjust seedling disease control measures when these two nematicides are used.

Aldicarb↗

PubMed2000

Soil pathogens and spatial patterns of seedling mortality in a temperate tree.

The Janzen-Connell hypothesis proposes that host-specific, distance- and/or density-dependent predators and herbivores maintain high tree diversity in tropical forests. Negative feedback between plant and soil communities could be a more effective mechanism promoting species coexistence because soil pathogens can increase rapidly in the presence of their host, causing conditions unfavourable for local conspecific recruitment. Here we show that a soil pathogen leads to patterns of seedling mortality in a temperate tree (Prunus serotina) as predicted by the Janzen-Connell hypothesis. In the field, the mean distance to parent of seedling cohorts shifted away from maternal trees over a period of 3 years. Seedlings were grown in soil collected 0-5 m or 25-30 m from Prunus trees. Sterilization of soil collected beneath trees improved seedling survival relative to unsterilized soil, whereas sterilization of distant soil did not affect survival. Pythium spp., isolated from roots of dying seedlings and used to inoculate healthy seedlings, decreased survival by 65% relative to controls. Our results provide the most complete evidence that native pathogens influence tree distributions, as predicted by the Janzen-Connell hypothesis, and suggest that similar ecological mechanisms operate in tropical and temperate forests.

Biological Evolution↗

PubMed2003

De novo formation, fusion and fission of mammalian COPII-coated endoplasmic reticulum exit sites.

Transport between the endoplasmic reticulum (ER) and Golgi is mediated by the sequential action of the COPII and COPI coat complexes. COPII subunits are recruited to the ER membrane where they mediate the selection of cargo for transport to the Golgi, and also membrane deformation and vesicle formation. New ER exit sites can be generated by lateral growth and medial fission (in Pythium sp.) or by de novo formation (in Pichia pastoris) but it is not known how mammalian ER exit sites form. Here, time-lapse imaging of COPII-coated structures in live mammalian cells reveals that the number of ER export sites increases greatly during interphase by de novo formation. These results show the fusion of pre-existing ER export sites and the fission of larger structures. These three mechanisms of de novo formation, fusion and fission probably cooperate to regulate the size of these sites in mammalian cells.

Animals↗

PubMed1999

In vitro and in vivo antagonism of pathogenic turfgrass fungi by Streptomyces hygroscopicus strains YCED9 and WYE53.

Disease prevention is a current practice used to minimize fungal diseases of turfgrasses in lawns and golf greens. Prevention is accomplished through fungicide applications, and by periodic thatch removal. During the development of a microbial biodethatch product utilizing the lignocellulose-degrading Streptomyces hygroscopicus strains YCED9 and WYE53, we demonstrated using in vitro plate antagonism bioassays that both strains are antagonists of various turfgrass fungal pathogens. These activities were present when the cultures were growing on thatch, as demonstrated by antifungal antagonism bioassays with culture filtrates. Experiments conducted using a growth chamber demonstrated that a bio-dethatch formulation containing spores of strains YCED9 and WYE53 in a zeolite carrier, provided protection for Kentucky bluegrass seedlings against turfgrass pathogens, including Pythium ultimum, Fusarium oxysporum, Rhizoctonia solani, Sclerotinia homeocarpa, Gaeumannomyces graminis and Microdochium nivale. Results showed that by integrating the use of the S. hygroscopicus YCED9/WYE53 bio-dethatch formulation into routine turf management practices, it should be possible to both minimize thatch build-up while also controlling fungal turfgrass diseases by way of the antifungal biocontrol activity of these strains. This in turn would help control fungal pathogens in turfgrass while minimizing the need for routine chemical fungicide applications.

Fungi↗

PubMed2003

RsmY, a small regulatory RNA, is required in concert with RsmZ for GacA-dependent expression of biocontrol traits in Pseudomonas fluorescens CHA0.

In the plant-beneficial soil bacterium and biocontrol model organism Pseudomonas fluorescens CHA0, the GacS/GacA two-component system upregulates the production of biocontrol factors, i.e. antifungal secondary metabolites and extracellular enzymes, under conditions of slow, non-exponential growth. When activated, the GacS/GacA system promotes the transcription of a small regulatory RNA (RsmZ), which sequesters the small RNA-binding protein RsmA, a translational regulator of genes involved in biocontrol. The gene for a second GacA-regulated small RNA (RsmY) was detected in silico in various pseudomonads, and was cloned from strain CHA0. RsmY, like RsmZ, contains several characteristic GGA motifs. The rsmY gene was expressed in strain CHA0 as a 118 nt transcript which was most abundant in stationary phase, as revealed by Northern blot and transcriptional fusion analysis. Transcription of rsmY was enhanced by the addition of the strain's own supernatant extract containing a quorum-sensing signal and was abolished in gacS or gacA mutants. An rsmA mutation led to reduced rsmY expression, via a gacA-independent mechanism. Overexpression of rsmY restored the expression of target genes (hcnA, aprA) to gacS or gacA mutants. Whereas mutants deleted for either the rsmY or the rsmZ structural gene were not significantly altered in the synthesis of extracellular products (hydrogen cyanide, 2,4-diacetylphloroglucinol, exoprotease), an rsmY rsmZ double mutant was strongly impaired in this production and in its biocontrol properties in a cucumber-Pythium ultimum microcosm. Mobility shift assays demonstrated that multiple molecules of RsmA bound specifically to RsmY and RsmZ RNAs. In conclusion, two small, untranslated RNAs, RsmY and RsmZ, are key factors that relieve RsmA-mediated regulation of secondary metabolism and biocontrol traits in the GacS/GacA cascade of strain CHA0.

Bacterial Proteins↗

PubMed2001

Rapid identification of tissue micro-organisms in skin biopsy specimens from domestic animals using polyclonal BCG antibody.

Immunostaining with polyclonal anti-Mycobacterium bovis (BCG) was evaluated as a single screening method for the histological identification of micro-organisms in skin biopsy specimens from various veterinary species. Confirmed archival cases infected with Mycobacteria, Nocardia, Actinobacillus, Actinomyces, Streptococcus/Staphylococcus, Dermatophilus, spirochetes, Blastomyces, Coccidioides, Cryptococcus, Histoplasma, dermatophytes, Malassezia, Sporothrix, Leishmania, Pythium, phaeohyphomycetes and Prototheca organisms were selected. A total of 70 skin biopsy specimens from the dog, cat, horse, ox and llama were evaluated. The anti-BCG immunostain labelled bacteria and fungi with high sensitivity and minimal background staining but did not label spirochetes and protozoa (Leishmania). Differences were not noted between veterinary species. The results indicate that immunostaining with polyclonal anti-BCG is a suitable screening technique for the rapid identification of most common bacterial and fungal organisms in paraffin-embedded specimens. Also, mycobacterial and nocardial organisms were identified more readily with the anti-BCG immunostain in comparison to the histochemical stains.

Animals↗

PubMed2003

Cure of orthopaedic infection with Scedosporium prolificans, using voriconazole plus terbinafine, without the need for radical surgery.

Scedosporium prolificans infections of normal hosts usually require extensive debridement and sometimes amputation to effect cure, due to the intrinsic resistance of this species to available antifungal agents. Newer agents have not tested favourably. Variable results are obtained with voriconazole, and 100% resistance is described with echinocandins. Itraconazole and terbinafine has offered synergy against various moulds including S. prolificans. In vivo success is reported with the azole/terbinafine combination in S. apiospermum pulmonary infection and Pythium insidiosum periorbital cellulitis. We report a case of orthopaedic infection in a non-immunocompromised host with S. prolificans, in which the combinations of itraconazole/terbinafine and voriconazole/terbinafine showed synergy in vitro, and success was achieved without radical surgery, using voriconazole and terbinafine.

Aged↗

PubMed2001

Breeding of mycoparasitic Trichoderma strains for heavy metal resistance.

AIMS: This study was designed to investigate the effects of 10 heavy metals on the in vitro activities of beta-glucosidase, cellobiohydrolase, beta-xylosidase and endoxylanase enzymes for six strains of Trichoderma, and to isolate and characterize heavy metal-resistant mutants. METHODS AND RESULTS: At a concentration of 1 mmol, only mercury showed significant inhibitory effects on the in vitro enzyme activities; in all other cases, the enzymes remained active. A total of 177 heavy metal-resistant mutants were isolated and tested for cross-resistance to other heavy metals. Some mutants were effective antagonists of Fusarium, Pythium and Rhizoctonia strains, even on media containing the respective heavy metals. CONCLUSION: Trichoderma strains could be developed as biocontrol agents that are effective against plant pathogenic fungi, even under heavy metal stress. SIGNIFICANCE AND IMPACT OF THE STUDY: Trichoderma mutants resistant to heavy metals might be of value for use with heavy metal-containing pesticides, as part of an integrated plant protection system.

Drug Resistance, Fungal↗