| microorganisms in the rhizosphere of wheat colonized by the fungus gaeumannomyces graminis var. tritici. | the population of microorganisms in wheat rhizosphere changed in the presence of the fungus gaeumannomyces graminis var. tritici causing the take-all of wheat. in the majority of cases when the soil was artificially contaminated by the fungus, both the number of bacteria in the rhizosphere and the bacteria/fungi ratio temporarily increased. at the beginning bacteria growing in the presence of nh4+ predominated, later bacteria utilizing organic n-substances prevailed. pseudomonas fluorescens and ... | 1979 | 112016 |
| effect of bacterial polysaccharides on the growth of gaeumannomyces graminis var. tritici and wheat roots. | agrobacterium sp. and related species which in the soil and in the rhizosphere of wheat accompany the fungus gaemannomyces graminis var. tritici and cause take-all of the wheat roots produced polysaccharides in pure cultures (glucans, mannoglucans and galactomannoglucans). these polysaccharides were utilized better by the mycelium of g. graminis than glucose and polysaccharides of plant origin that occurred on the surface of wheat roots (the so-called mucigel). at lower concentrations these bact ... | 1979 | 468081 |
| a volatile factor inducing transmissible lysis in gaeumannomyces graminis (sacc.) arx and olivier var. tritici walker. | filtered water extract of gabalong soil with a recent history of take-all in wheat caused lytic plaques to form in agar cultures of a virulent strain of gaeumannomyces graminis var. tritici. the plaques resembled those produced by bdellovibrio on plate seeded with bacteria. however, there was no evidence of the presence of bacteria, viruses, or mycoplasmas. the lytic factor was transmissible in culture filtrates to fresh subcultures of the fungus. exposure of young healthy colonies to sublethal ... | 1975 | 1116042 |
| cloning and heterologous expression of the phenazine biosynthetic locus from pseudomonas aureofaciens 30-84. | pseudomonas aureofaciens strain 30-84 suppresses take-all disease of wheat caused by gaeumannomyces graminis var. tritici. three antibiotics, phenazine-1-carboxylic acid, 2-hydroxyphenazine-1-carboxylic acid, and 2-hydroxyphenazine, were responsible for disease suppression. tn5-induced mutants deficient in production of one or more of the antibiotics (phz-) were significantly less suppressive than the parental strain. cosmids plsp259 and plsp282 from a genomic library of strain 30-84 restored ph ... | 1992 | 1325219 |
| contribution of phenazine antibiotic biosynthesis to the ecological competence of fluorescent pseudomonads in soil habitats. | phenazine antibiotics produced by pseudomonas fluorescens 2-79 and pseudomonas aureofaciens 30-84, previously shown to be the principal factors enabling these bacteria to suppress take-all of wheat caused by gaeumannomyces graminis var. tritici, also contribute to the ecological competence of these strains in soil and in the rhizosphere of wheat. strains 2-79 and 30-84, their tn5 mutants defective in phenazine production (phz-), or the mutant strains genetically restored for phenazine production ... | 1992 | 1514808 |
| genetic analysis of the antifungal activity of a soilborne pseudomonas aureofaciens strain. | pseudomonas aureofaciens q2-87 produces the antibiotic 2,4-diacetophloroglucinol (phl), which inhibits gaeumannomyces graminis var. tritici and other fungi in vitro. strain q2-87 also provides biological control of take-all, a root disease of wheat caused by this fungus. to assess the role of phl in the antifungal activity of strain q2-87, a genetic analysis of antibiotic production was conducted. two mutants of q2-87 with altered antifungal activity were isolated by site-directed mutagenesis wi ... | 1991 | 1660695 |
| relative importance of fluorescent siderophores and other factors in biological control of gaeumannomyces graminis var. tritici by pseudomonas fluorescens 2-79 and m4-80r. | pseudomonas fluorescens 2-79 suppresses take-all, a major root disease of wheat caused by gaeumannomyces graminis var. tritici. the bacteria produce an antibiotic, phenazine-1-carboxylic acid (pca), and a fluorescent pyoverdin siderophore. previous studies have established that pca has an important role in the biological control of take-all but that antibiotic production does not account fully for the suppressiveness of the strain. to define the role of the pyoverdin siderophore more precisely, ... | 1991 | 1838240 |
| role of a phenazine antibiotic from pseudomonas fluorescens in biological control of gaeumannomyces graminis var. tritici. | pseudomonas fluorescens 2-79 (nrrl b-15132) and its rifampin-resistant derivative 2-79rn10 are suppressive to take-all, a major root disease of wheat caused by gaeumannomyces graminis var. tritici. strain 2-79 produces the antibiotic phenazine-1-carboxylate, which is active in vitro against g. graminis var. tritici and other fungal root pathogens. mutants defective in phenazine synthesis (phz-) were generated by tn5 insertion and then compared with the parental strain to determine the importance ... | 1988 | 2841289 |
| characterization of an antibiotic produced by a strain of pseudomonas fluorescens inhibitory to gaeumannomyces graminis var. tritici and pythium spp. | the production, isolation, and characterization of an antibiotic substance from cultures of pseudomonas fluorescens 2-79 (nrrl b-15132) is described. p. fluorescens 2-79 originally was isolated from the roots of wheat and is suppressive to the wheat root disease take-all caused by gaeumannomyces graminis var. tritici. the antibiotic was isolated from potato glucose broth cultures of strain 2-79 by solvent extraction. it was purified by silica gel column chromatography and was a greenish yellow, ... | 1986 | 3087284 |
| sequence complexities of the nuclear and mitochondrial genomes of the take-all fungus, gaeumannomyces graminis var. tritici. | the nuclear (n) and mitochondrial (mt) genomes of the take-all fungus, gaeumannomyces graminis var. tritici, were examined by reassociation kinetics with escherichia coli dna as internal standard. only one kinetic component was detected in each dna, with second-order rate constants of 0.022 m-1 s-1 for ndna and 10.9 m-1 s-1 for mtdna, corresponding to sequence complexities of 29 x 10(6) base pairs and 60 x 10(3) base pairs respectively. | 1983 | 6663284 |
| rhizosphere microflora and colonization of wheat roots by gaeumannomyces graminis var. tritici after foliar application of urea and benomyl. | the effect of foliar application of 2% urea and 0.6% benomyl on changes in colonization of the rhizosphere by microorganisms and of roots by the fungus gaeumannomyces graminis (sacc.) arx et olivier var. tritici walker was followed in vegetation glass-house experiments. treatment with a urea solution resulted in increased counts of bacteria (82%), pseudomonas fluorescens (46%), agrobacterium sp. (31%) and antagonistic bacteria with respect to the used fungus isolate and in a decreased occurrence ... | 1980 | 6777280 |
| control of microorganisms in the rhizosphere of wheat by inoculation of seeds with pseudomonas putida and by foliar application of urea. | after inoculation of wheat seeds with various bacterial strains germination of plants was usually inhibited at first but growth was stimulated later. after inoculation with pseudomonas putida k 11 producing physiologically active compounds the total number of bacteria increased together with the bacteria: fungi ratio in the rhizosphere. these characteristic were further increased after foliar application of urea due to increased root exudation. dry mass of upper wheat parts was about 14--80% hig ... | 1981 | 7203287 |
| liquid-culture ph, temperature, and carbon (not nitrogen) source regulate phenazine productivity of the take-all biocontrol agent pseudomonas fluorescens 2-79. | strain 2-79 is a biocontrol agent against take-all, an important disease of wheat caused by gaeumannomyces graminis var. tritici. in the rhizosphere, it produces the antibiotic phenazine 1-carboxylic acid (pca) as the primary means of disease suppression. one barrier to commercial use of phenazine-producing pseudomonads, like strain 2-79, is the lack of liquid-culture technology for mass production. for instance, there is little published research concerning the impact of liquid-culture secondar ... | 1995 | 7576546 |
| antifungal metabolites from trichoderma harzianum. | a detailed examination of the metabolites produced in liquid cultures by a strain of trichoderma harzianum, isolated from wheat roots, has resulted in the identification of a further five metabolites. two of these, cyclonerodiol [5] and the octaketide keto diol 6, have previously been isolated from a strain of trichoderma koningii. the structures of the three new octaketide-derived compounds 7, 8, and 10 have been deduced from spectroscopic and chemical studies. all newly isolated compounds show ... | 1993 | 8277317 |
| n-acyl-homoserine lactone-mediated regulation of phenazine gene expression by pseudomonas aureofaciens 30-84 in the wheat rhizosphere. | pseudomonas aureofaciens 30-84 is a soilborne bacterium that colonizes the wheat rhizosphere. this strain produces three phenazine antibiotics which suppress take-all disease of wheat by inhibition of the causative agent gaeumannomyces graminis var. tritici. phenazines also enhance survival of 30-84 within the wheat rhizosphere in competition with other organisms. expression of the phenazine biosynthetic operon is controlled by the phzr/phzi n-acyl-homoserine lactone (ahl) response system (l. s. ... | 1997 | 9401023 |
| characterization of a split respiratory pathway in the wheat "take-all" fungus, gaeumannomyces graminis var. tritici. | this article describes the first detailed analysis of mitochondrial electron transfer and oxidative phosphorylation in the pathogenic filamentous fungus, gaeumannomyces graminis var. tritici. while oxygen consumption was cyanide insensitive, inhibition occurred following treatment with complex iii inhibitors and the alternative oxidase inhibitor, salicylhydroxamic acid (sham). similarly, maintenance of a deltapsi across the mitochondrial inner membrane was unaffected by cyanide but sensitive to ... | 1998 | 9556599 |
| detoxification of benzoxazolinone allelochemicals from wheat by gaeumannomyces graminis var. tritici, g. graminis var. graminis, g. graminis var. avenae, and fusarium culmorum. | the ability of phytopathogenic fungi to overcome the chemical defense barriers of their host plants is of great importance for fungal pathogenicity. we studied the role of cyclic hydroxamic acids and their related benzoxazolinones in plant interactions with pathogenic fungi. we identified species-dependent differences in the abilities of gaeumannomyces graminis var. tritici, gaeumannomyces graminis var. graminis, gaeumannomyces graminis var. avenae, and fusarium culmorum to detoxify these allelo ... | 1998 | 9647804 |
| purification and characterization of a secreted laccase of gaeumannomyces graminis var. tritici. | we purified a secreted fungal laccase from filtrates of gaeumannomyces graminis var. tritici cultures induced with copper and xylidine. the active protein had an apparent molecular mass of 190 kda and yielded subunits with molecular masses of 60 kda when denatured and deglycosylated. this laccase had a pi of 5.6 and an optimal ph of 4.5 with 2,6-dimethoxyphenol as its substrate. like other, previously purified laccases, this one contained several copper atoms in each subunit, as determined by in ... | 1999 | 10388705 |
| genetic diversity and biological control activity of novel species of closely related pseudomonads isolated from wheat field soils in south australia. | rhizobacteria closely related to two recently described species of pseudomonads, pseudomonas brassicacearum and pseudomonas thivervalensis, were isolated from two geographically distinct wheat field soils in south australia. isolation was undertaken by either selective plating or immunotrapping utilizing a polyclonal antibody raised against p. brassicacearum. a subset of 42 isolates were characterized by amplified 16s ribosomal dna restriction analysis (ardra), biolog analysis, and gas chromatog ... | 2000 | 10742249 |
| terpenoids and flavonoids from artemisia species. | a phytochemical reinvestigation of the aerial parts of artemisia sieversiana gave a new guaianolide and two known flavones (chrysosplenetin and 5-hydroxy-3',4',6,7-tetramethoxyflavone). antifungal fractions derived from the chloroform extract of a. annua afforded two cadinane derivatives (arteannuin b and artemisinin), oleanolic acid, beta-sitosterol, stigmasterol, and the four flavones artemetin, bonanzin, eupalitin and chrysosplenetin. their structures were elucidated by spectral methods. all ... | 2000 | 10865468 |
| antimicrobial activities of ferulago essential oils. | essential oils from ferulago asparagifolia boiss., f. galbanifera (miller) w. koch, f. humilis boiss. (endemic), f. trachycarpa boiss. growing in turkey were evaluated against 15 microorganisms for their antifungal and antibacterial activity using an agar tube dilution and microdilution broth susceptibility assay, respectively. the essential oil compositions were investigated by gc/ms. inhibitory effects against escherichia coli, enterobacter aerogenes, candida albicans, gaeumannomyces graminis ... | 2000 | 11204191 |
| antifungal activity of artemisia annua endophyte cultures against phytopathogenic fungi. | artemisia annua, well recognized for its production of antimalarial drug artemisinin, is seldom attacked by any of phytopathogenic fungi, which could be partially associated with the presence of endophytes. present investigation is aiming at disclosing whether the endophytes inside a. annua produce antifungal substances. a total of 39 endophytes were isolated and fermented, and the ferment broth was evaluated in vitro for the antifungal activity against crop-threatening fungi gaeumannomyces gram ... | 2001 | 11434973 |
| changes in populations of rhizosphere bacteria associated with take-all disease of wheat. | take-all, caused by gaeumannomyces graminis var. tritici, is one of the most important fungal diseases of wheat worldwide. knowing that microbe-based suppression of the disease occurs in monoculture wheat fields following severe outbreaks of take-all, we analyzed the changes in rhizosphere bacterial communities following infection by the take-all pathogen. several bacterial populations were more abundant on diseased plants than on healthy plants, as indicated by higher counts on a pseudomonas-se ... | 2001 | 11571137 |
| molecular mechanisms of defense by rhizobacteria against root disease. | genetic resistance in plants to root diseases is rare, and agriculture depends instead on practices such as crop rotation and soil fumigation to control these diseases. "induced suppression" is a natural phenomenon whereby a soil due to microbiological changes converts from conducive to suppressive to a soilborne pathogen during prolonged monoculture of the susceptible host. our studies have focused on the wheat root disease "take-all," caused by the fungus gaeumannomyces graminis var. tritici, ... | 1995 | 11607544 |
| the dark side of the mycelium: melanins of phytopathogenic fungi. | melanins are darkly pigmented polymers that protect organisms against environmental stress. even when not directly involved in pathogenesis, fungal melanin is likely required by melanizing phytopathogens for survival in the environment. however, some phytopathogenic fungi that produce melanized appressoria for host invasion require appressorial melanogenesis for pathogenicity. much less is known about the role melanins play in pathogenesis during infection by other phytopathogens that do not rel ... | 1999 | 11701831 |
| cloning, characterization, and transcription of three laccase genes from gaeumannomyces graminis var. tritici, the take-all fungus. | gaeumannomyces graminis var. tritici, a filamentous ascomycete, is an important root pathogen of cereals that causes take-all disease and results in severe crop losses worldwide. previously we identified a polyphenol oxidase (laccase) secreted by the fungus when induced with copper. here we report cloning and partial characterization of three laccase genes (lac1, lac2, and lac3) from g. graminis var. tritici. predicted polypeptides encoded by these genes had 38 to 42% amino acid sequence identit ... | 2002 | 11872481 |
| mechanisms of natural soil suppressiveness to soilborne diseases. | suppressive soils are characterized by a very low level of disease development even though a virulent pathogen and susceptible host are present. biotic and abiotic elements of the soil environment contribute to suppressiveness, however most defined systems have identified biological elements as primary factors in disease suppression. many soils possess similarities with regard to microorganisms involved in disease suppression, while other attributes are unique to specific pathogen-suppressive so ... | 2002 | 12448751 |
| [the production of phenazine antibiotics by the pseudomonas aureofaciens strain with plasmid-controlled resistance to cobalt and nickel]. | plasmid pbs501 responsible for the resistance of the wild-type pseudomonas sp. bs501 (pbs501) to cobalt and nickel ions was conjugatively transferred to the rhizosphere pseudomonas aureofaciens strain bs1393, which is able to synthesize phenazine antibiotics and to suppress a wide range of phytopathogenic microorganisms. the transconjugant p. aureofaciens bs1393 (pbs501) turned out to be resistant to cobalt and nickel with an mic of 8 mm. when grown in a synthetic medium with 0.25 mm cobalt, the ... | 2002 | 12526199 |
| identification and manipulation of soil properties to improve the biological control performance of phenazine-producing pseudomonas fluorescens. | pseudomonas fluorescens 2-79rn(10) protects wheat against take-all disease caused by gaeumannomyces graminis var. tritici; however, the level of protection in the field varies from site to site. identification of soil factors that exert the greatest influence on disease suppression is essential to improving biocontrol. in order to assess the relative importance of 28 soil properties on take-all suppression, seeds were treated with strain 2-79rn(10) (which produces phenazine-1-carboxylate [pca(+) ... | 2003 | 12788734 |
| an attempt to protect winter wheat against gaeumannomyces graminis var. tritici by the use of rhizobacteria pseudomonas fluorescens and bacillus mycoides. | pseudomonas fluorescens strains iii107 and ii21 and bacillus mycoides strains jc192 and k184, stimulating growth of winter wheat, were chosen for the studies. the bacterial strains inhibited on agar nutrient medium the growth of gaeumannomyces graminis var. tritici (ggt)--the pathogenic fungus causing take-all on wheat. both strains of pseudomonads synthesized relatively high amounts of fe3+ chelators. the strains of bacilli were characterized by the very fast spreading on agar media. furthermor ... | 2004 | 15478355 |
| changes in population structure of the soilborne fungus gaeumannomyces graminis var. tritici during continuous wheat cropping. | a method was developed to assess the genetic structure of gaeumannomyces graminis var. tritici (ggt) populations and test the hypothesis of an association between disease level in the field with changes in pathogen populations. a long-term wheat monoculture experiment, established since 1994, generated different take-all epidemics with varying the number of wheat crop successions in the 1999-2000 cropping season. genetic polymorphism in ggt populations was investigated over natural, local epidem ... | 2004 | 15479250 |
| apoplastic extracts from a transgenic wheat line exhibiting lesion-mimic phenotype have multiple pathogenesis-related proteins that are antifungal. | a transgenic wheat line constitutively expressing genes encoding a class iv acidic chitinase and an acidic beta-1,3-glucanase, showed significant delay in spread of fusarium head blight (scab) disease under greenhouse conditions. in an earlier work, we observed a lesion-mimic phenotype in this transgenic line when homozygous for transgene loci. apoplastic fluid (af) extracted from the lesion-mimic plants had pathogenesis-related (pr) proteins belonging to families of beta-1,3-glucanases, chitina ... | 2004 | 15597736 |
| dna probe for identification of the take-all fungus, gaeumannomyces graminis. | a 4.3-kilobase mitochondrial dna fragment was cloned from gaeumannomyces graminis var. tritici, the causative agent of take-all disease of wheat. although this dna fragment hybridized with all three varieties of g. graminis, it showed little homology with dna from other fungi and thus should be useful for identification of gaeumannomyces sp. recovered from infected plants. | 1989 | 16347842 |
| production of the antibiotic phenazine-1-carboxylic acid by fluorescent pseudomonas species in the rhizosphere of wheat. | pseudomonas fluorescens 2-79 and p. aureofaciens 30-84 produce the antibiotic phenazine-1-carboxylic acid and suppress take-all, an important root disease of wheat caused by gaeumannomyces graminis var. tritici. to determine whether the antibiotic is produced in situ, wheat seeds were treated with strain 2-79 or 30-84 or with phenazine-nonproducing mutants or were left untreated and then were sown in natural or steamed soil in the field or growth chamber. the antibiotic was isolated only from ro ... | 1990 | 16348176 |
| effects of fungal root pathogens on the population dynamics of biocontrol strains of fluorescent pseudomonads in the wheat rhizosphere. | the influences of gaeumannomyces graminis var. tritici (which causes take-all of wheat), rhizoctonia solani ag-8 (which causes rhizoctonia root rot of wheat), pythium irregulare, p. aristosporum, and p. ultimum var. sporangiiferum (which cause pythium root rot of wheat) on the population dynamics of pseudomonas fluorescens 2-79 and q72a-80 (bicontrol strains active against take-all and pythium root rot of wheat, respectively) in the wheat rhizosphere were examined. root infection by either g. gr ... | 1991 | 16348532 |
| gluconic acid: an antifungal agent produced by pseudomonas species in biological control of take-all. | pseudomonas strain an5 (ps. str. an5), a non-fluorescent australian bacterial isolate, is an effective biological control (biocontrol) agent of the take-all disease of wheat caused by the fungus gaeumannomyces graminis var. tritici (ggt). ps. str. an5 controls ggt by producing an antifungal compound which was purified by thin layer and column chromatography, and identified by nmr and mass spectroscopic analysis to be d-gluconic acid. commercially bought pure gluconic acid strongly inhibited ggt. ... | 2006 | 16445952 |
| the role of dsba in colonization of the wheat rhizosphere by pseudomonas fluorescens q8r1-96. | certain well-conserved genes in fluorescent pseudomonas spp. are involved in pathogenic interactions between the bacteria and evolutionarily diverse hosts including plants, insects and vertebrate animals. one such gene, dsba, encodes a periplasmic disulfide-bond-forming enzyme implicated in the biogenesis of exported proteins and cell surface structures. this study focused on the role of dsba in pseudomonas fluorescens q8r1-96, a biological control strain that produces the antibiotic 2,4-diacety ... | 2006 | 16514165 |
| variation in sensitivity of gaeumannomyces graminis to antibiotics produced by fluorescent pseudomonas spp. and effect on biological control of take-all of wheat. | isolates of gaeumannomyces graminis var. tritici, the causal agent of take-all of wheat, varied in sensitivity in vitro to the antibiotics phenazine-1-carboxylic acid (pca) and 2,4-diacetylphloroglucinol (phl) produced by fluorescent pseudomonas spp. shown previously to have potential for biological control of this pathogen. none of the four isolates of g. graminis var. avenae examined were sensitive to either of the antibiotics in vitro at the concentrations tested. the single isolate of g. gra ... | 1995 | 16535070 |
| major secondary metabolites produced by two commercial trichoderma strains active against different phytopathogens. | trichoderma harzianum strains t22 and t39 are two micro-organisms used as active agents in a variety of commercial biopesticides and biofertilizers and widely applied amongst field and greenhouse crops. the production, isolation, biological and chemical characterization of the main secondary metabolites produced by these strains are investigated. | 2006 | 16869896 |
| role of ptsp, orft, and sss recombinase genes in root colonization by pseudomonas fluorescens q8r1-96. | pseudomonas fluorescens q8r1-96 produces 2,4-diacetylphloroglucinol (2,4-dapg), a polyketide antibiotic that suppresses a wide variety of soilborne fungal pathogens, including gaeumannomyces graminis var. tritici, which causes take-all disease of wheat. strain q8r1-96 is representative of the d-genotype of 2,4-dapg producers, which are exceptional because of their ability to aggressively colonize and maintain large populations on the roots of host plants, including wheat, pea, and sugar beet. in ... | 2006 | 16936061 |
| role of 2,4-diacetylphloroglucinol-producing fluorescent pseudomonas spp. in the defense of plant roots. | plants have evolved strategies of stimulating and supporting specific groups of antagonistic microorganisms in the rhizosphere as a defense against diseases caused by soilborne plant pathogens owing to a lack of genetic resistance to some of the most common and widespread soilborne pathogens. some of the best examples of natural microbial defense of plant roots occur in disease suppressive soils. soil suppressiveness against many different diseases has been described. take-all is an important ro ... | 2007 | 17058178 |
| linear relationship between gaeumannomyces graminis var. tritici (ggt) genotypic frequencies and disease severity on wheat roots in the field. | in order to investigate potential links existing between gaeumannomyces graminis var. tritici (ggt) population structure and disease development during polyetic take-all epidemics in sequences of ggt host cereals, seven epidemics in fields with different cropping histories were monitored during the seasons 2001/2002 (two fields), 2002/2003 (two fields) and 2003/2004 (three fields). take-all incidence and severity were measured at stem elongation and ggt populations were characterized. the 73 iso ... | 2007 | 17222147 |
| altering the ratio of phenazines in pseudomonas chlororaphis (aureofaciens) strain 30-84: effects on biofilm formation and pathogen inhibition. | pseudomonas chlororaphis strain 30-84 is a plant-beneficial bacterium that is able to control take-all disease of wheat caused by the fungal pathogen gaeumannomyces graminis var. tritici. the production of phenazines (pzs) by strain 30-84 is the primary mechanism of pathogen inhibition and contributes to the persistence of strain 30-84 in the rhizosphere. pz production is regulated in part by the phzr/phzi quorum-sensing (qs) system. previous flow cell analyses demonstrated that qs and pzs are i ... | 2008 | 18263718 |
| colonization of barley roots by endophytic fungi and their reduction of take-all caused by gaeumannomyces graminis var. tritici. | fungal root endophytes obtained from natural vegetation were tested for antifungal activity in dual culture tests against the root pathogen gaeumannomyces graminis var. tritici. fifteen isolates, including acremonium blochii, acremonium furcatum, aspergillus fumigatus, cylindrocarpon sp., cylindrocarpon destructans, dactylaria sp., fusarium equiseti, phoma herbarum, phoma leveillei, and a sterile mycelium, selected based on the dual culture test, were inoculated on barley roots in growth tubes u ... | 2008 | 18772922 |
| effect of mixed and single crops on disease suppressiveness of soils. | abstract the effect of mixed cropping on disease suppressiveness of soils was tested for two cropping systems, brussels sprouts-barley and triticale-white clover. disease suppressiveness of field soils was evaluated in bioassays for the soilborne pathogens rhizoctonia solani, fusarium oxysporum f. sp. lini, and gaeumannomyces graminis var. tritici. for both cropping systems, mixed cropping did not enhance disease suppressiveness of the soils. in some cases, soil cropped to barley alone was signi ... | 2005 | 18943364 |
| evidence of a multicopper oxidase in mn oxidation by gaeumannomyces graminis var. tritici. | abstract manganese (mn) oxidation by the plant-pathogenic fungus gaeumannomyces graminis var. tritici has been correlated with virulence in take-all disease. the mechanism of mn oxidation has not, however, been investigated adequately. research on bacteria and other fungi indicates that mn oxidation is most often the result of the activity of multicopper oxidases. to determine if g. graminis var. tritici oxidizes mn by similar means, the mn oxidizing factor (mof) produced by g. graminis var. tri ... | 2006 | 18943915 |
| genetic diversity of phld from 2,4-diacetylphloroglucinol-producing fluorescent pseudomonas spp. | abstract fluorescent pseudomonas spp. that produce 2,4-diacetylphloroglucinol (2,4-dapg) have biocontrol activity against damping-off, root rot, and wilt diseases caused by soilborne fungal pathogens, and play a key role in the natural suppression of gaeumannomyces graminis var. tritici, known as take-all decline. diversity within phld, an essential gene in the biosynthesis of 2,4-dapg, was studied by restriction fragment length polymorphism (rflp) analysis of 123 2,4-dapg-producing isolates fro ... | 2001 | 18944276 |
| an epidemiological analysis of the role of disease-induced root growth in the differential response of two cultivars of winter wheat to infection by gaeumannomyces graminis var. tritici. | abstract epidemiological modeling combined with parameter estimation of experimental data was used to examine differences in the contribution of disease-induced root production to the spread of take-all on plants of two representative yet contrasting cultivars of winter wheat, ghengis and savannah. a mechanistic model, including terms for primary infection, secondary infection, inoculum decay, and intrinsic and disease-induced root growth, was fitted to data describing changes in the numbers of ... | 2006 | 18944311 |
| modeling of take-all epidemics to evaluate the efficacy of a new seed-treatment fungicide on wheat. | abstract take-all, caused by gaeumannomyces graminis var. tritici, is a damaging disease of wheat that remains difficult to control. the efficacy of an experimental fungicide, applied as a seed treatment, was evaluated in five naturally infested field experiments conducted during three cropping seasons. plants were sampled and assessed for take-all incidence and severity at different growth stages. nonlinear models expressing disease variables as a function of degree-days were fitted to the obse ... | 1999 | 18944741 |
| dynamics of primary and secondary infection in take-all epidemics. | abstract using a combination of experimentation and mathematical modeling, the effects of initial (particulate) inoculum density on the dynamics of disease resulting from primary and secondary infection of wheat by the take-all fungus, gaeumannomyces graminis var. tritici, were tested. a relatively high inoculum density generated a disease progress curve that rose monotonically toward an asymptote. reducing the initial inoculum density resulted in a curve that initially was monotonic, rising to ... | 1999 | 18944808 |
| bacillus sp. l324-92 for biological control of three root diseases of wheat grown with reduced tillage. | abstract strain l324-92 is a novel bacillus sp. with biological activity against three root diseases of wheat, namely take-all caused by gaeumannomyces graminis var. tritici, rhizoctonia root rot caused by rhizoctonia solani ag8, and pythium root rot caused mainly by pythium irregulare and p. ultimum, that exhibits broad-spectrum inhibitory activity and grows at temperatures from 4 to 40 degrees c. these three root diseases are major yieldlimiting factors for wheat in the u.s. inland pacific nor ... | 1997 | 18945111 |
| population dynamics of bacillus sp. l324-92r(12) and pseudomonas fluorescens 2-79rn(10) in the rhizosphere of wheat. | abstract bacillus sp. l324-92 is suppressive to three root diseases of wheat, namely take-all caused by gaeumannomyces graminis var. tritici, rhizoctonia root rot caused by rhizoctonia solani ag8, and pythium root rot caused by several pythium species. populations of strain l324-92r(12), a rifampicin-resistant mutant of l324-92 applied as a seed treatment, were monitored in the rhizosphere and spermosphere of wheat and compared with populations of pseudomonas fluorescens 2-79rn(10), a known, rhi ... | 1997 | 18945112 |
| influence of crop management on take-all development and disease cycles on winter wheat. | abstract wheat was assessed at four crop growth stages for take-all (gaeumannomyces graminis var. tritici) in a series of field trials that studied the effects of five wheat management practices: sowing date, plant density, nitrogen fertilizer dose and form, and removal/burial of cereal straw. an equation expressing disease level as a function of degree days was fitted to the observed disease levels. this equation was based on take-all epidemiology and depended on two parameters reflecting the i ... | 1997 | 18945150 |
| production and characterization of a monoclonal antibody raised against surface antigens from mycelium of gaeumannomyces graminis var. tritici: evidence for an extracellular polyphenol oxidase. | abstract a murine monoclonal antibody (mab) of immunoglobulin class m (igm) was raised against surface antigens from gaeumannomyces graminis var. tritici and, by enzyme-linked immunosorbent assay, recognized isolates of g. graminis var. tritici, g. graminis var. avenae and g. graminis var. graminis. characterization of the antigen by heat and protease treatments showed that the epitope recognized by the mab was a protein. antigen production was detected only in live mycelia. immunofluorescence s ... | 1997 | 18945163 |
| the plant pathogenic fungus gaeumannomyces graminis var. tritici improves bacterial growth and triggers early gene regulations in the biocontrol strain pseudomonas fluorescens pf29arp. | in soil, some antagonistic rhizobacteria contribute to reduce root diseases caused by phytopathogenic fungi. direct modes of action of these bacteria have been largely explored; however, commensal interaction also takes place between these microorganisms and little is known about the influence of filamentous fungi on bacteria. an in vitro confrontation bioassay between the pathogenic fungus gaeumannomyces graminis var. tritici (ggt) and the biocontrol bacterial strain pseudomonas fluorescens pf2 ... | 2009 | 19121038 |
| feeding of the nematode acrobeloides nanus on bacteria. | information on the effect of bacteria-feeding nematodes on bacterial populations in the soil is sparse. we have isolated, cultured, and microscopically examined bacteria and nematodes coexisting within an agricultural soil and have studied their feeding relationship. the bacterium pseudomonas corrugata isolate 2140r is a biocontrol agent against the pathogenic fungus gaeumannomyces graminis var. tritici. the nematode acrobeloides nanus is a cosmopolitan, bacteria-feeding organism widespread in a ... | 1993 | 19279801 |
| diversity, virulence, and 2,4-diacetylphloroglucinol sensitivity of gaeumannomyces graminis var. tritici isolates from washington state. | we determined whether isolates of the take-all pathogen gaeumannomyces graminis var. tritici become less sensitive to 2,4-diacetylphloroglucinol (2,4-dapg) during wheat monoculture as a result of exposure to the antibiotic over multiple growing seasons. isolates of g. graminis var. tritici were baited from roots of native grasses collected from noncropped fields and from roots of wheat from fields with different cropping histories near lind, ritzville, pullman, and almota, wa. isolates were char ... | 2009 | 19351242 |
| role of gluconic acid production in the regulation of biocontrol traits of pseudomonas fluorescens cha0. | the rhizobacterium pseudomonas fluorescens cha0 promotes the growth of various crop plants and protects them against root diseases caused by pathogenic fungi. the main mechanism of disease suppression by this strain is the production of the antifungal compounds 2,4-diacetylphloroglucinol (dapg) and pyoluteorin (plt). direct plant growth promotion can be achieved through solubilization of inorganic phosphates by the production of organic acids, mainly gluconic acid, which is one of the principal ... | 2009 | 19376896 |
| persistence of dna of gaeumannomyces graminis var. tritici in soil as measured by a dna-based assay. | there are an increasing number of assays available for fungal plant pathogens based on dna technology. we have developed such an assay for gaeumannomyces graminis var. tritici (ggt) in soil, using slot-blot hybridisation. to ensure the validity of dna-based soil assays for the fungus, it is important to determine the stability of ggt dna in soil. this study was undertaken to quantify the dna degradation of dead ggt in soil using a dna-based assay. mycelia were killed using various treatments, th ... | 2004 | 19712330 |
| polymorphisms within the prnd and pltc genes from pyrrolnitrin and pyoluteorin-producing pseudomonas and burkholderia spp. | abstract pyrrolnitrin (prn) and pyoluteorin (plt) are broad-spectrum antibiotics produced by several strains of pseudomonas and burkholderia species. both antibiotics play an important role in the suppression of multiple plant pathogenic fungi. primers were developed from conserved sequences and amplified prnd and pltc fragments from 18 pseudomonas and four burkholderia spp. of worldwide origin that produce either prn or plt or both. subsequent rflp (restriction fragment length polymorphisms) an ... | 2003 | 19719693 |
| rhizosphere bacterial communities associated with disease suppressiveness stages of take-all decline in wheat monoculture. | the decline of take-all disease (gaeumannomyces graminis var. tritici), which may take place during wheat monocropping, involves plant-protecting, root-colonizing microorganisms. so far, however, most work has focused on antagonistic fluorescent pseudomonads. our objective was to assess the changes in rhizobacterial community composition during take-all decline of field-grown wheat. the study was based on the development and utilization of a taxonomic 16s rrna-based microarray of 575 probes, cou ... | 2009 | 19732350 |
| effect of wheat roots infected with the pathogenic fungus gaeumannomyces graminis var. tritici on gene expression of the biocontrol bacterium pseudomonas fluorescens pf29arp. | traits contributing to the competence of biocontrol bacteria to colonize plant roots are often induced in the rhizosphere in response to plant components. these interactions have been studied using the two partners in gnotobiotic systems. however, in nature, beneficial or pathogenic fungi often colonize roots. influence of these plant-fungus interactions on bacterial behavior remains to be investigated. here, we have examined the influence of colonization of wheat roots by the take-all fungus ga ... | 2009 | 19888826 |
| isolation, characterization, and sensitivity to 2,4-diacetylphloroglucinol of isolates of phialophora spp. from washington wheat fields. | dark pigmented fungi of the gaeumannomyces-phialophora complex were isolated from the roots of wheat grown in fields in eastern washington state. these fungi were identified as phialophora spp. on the basis of morphological and genetic characteristics. the isolates produced lobed hyphopodia on wheat coleoptiles, phialides, and hyaline phialospores. sequence comparison of internal transcribed spacer regions indicated that the phialophora isolates were clearly separated from other gaeumannomyces s ... | 2010 | 20373960 |
| [molecular-genetic polymorphism of cellular lines of wheat resistant to cultural filtrate gaeumannomyces graminis var. tritici and plant-regenerants from them]. | dna polymorphism of wheat cellular lines resistant to culture filtrate of g. graminis var. tritici and regenerated plants has been investigated using issr-analysis. specific changes in dna sequence were revealed in resistant calluses. it was established, that all resistant cellular lines differed by the presence of specific amplicons of 2347 bp (primer 5'-tctctctctctctctcg-3') and 1745 bp (primer 5'-agagagagagagagagtc-3'), as well as the absence of the amplicon of 1108 bp (primer 5'-acacacacacac ... | 2009 | 20458963 |
| comparison of barley succession and take-all disease as environmental factors shaping the rhizobacterial community during take-all decline. | the root disease take-all, caused by gaeumannomyces graminis var. tritici, can be managed by monoculture-induced take-all decline (tad). this natural biocontrol mechanism typically occurs after a take-all outbreak and is believed to arise from an enrichment of antagonistic populations in the rhizosphere. however, it is not known whether these changes are induced by the monoculture or by ecological rhizosphere conditions due to a disease outbreak and subsequent attenuation. this question was addr ... | 2010 | 20525871 |
| gaeumannomyces graminis, the take-all fungus and its relatives. | summary take-all, caused by the fungus gaeumannomyces graminis var. tritici, is the most important root disease of wheat worldwide. many years of intensive research, reflected by the large volume of literature on take-all, has led to a considerable degree of understanding of many aspects of the disease. however, effective and economic control of the disease remains difficult. the application of molecular techniques to study g. graminis and related fungi has resulted in some significant advances, ... | 2004 | 20565593 |
| periodicity in host availability does not account for evolutionary branching as observed in many plant pathogens: an application to gaeumannomyces graminis var. tritici. | periodicity in host availability is common in agricultural systems. although it is known to have profound effects on plant pathogen abundance, the evolutionary consequences of periodicity for the pathogen population have not previously been analyzed. an epidemiological model incorporating periodic absence of the host crop is combined with the theory of adaptive dynamics to determine whether or not seasonality in host presence plays a role in the occurrence of evolutionary branching, leading to c ... | 2010 | 20932165 |
| the biocontrol bacterium pseudomonas fluorescens pf29arp strain affects the pathogenesis-related gene expression of the take-all fungus gaeumannomyces graminis var. tritici on wheat roots. | the main effects of antagonistic rhizobacteria on plant pathogenic fungi are antibiosis, fungistasis or an indirect constraint through the induction of a plant defence response. to explore different biocontrol mechanisms, an in vitro confrontation assay was conducted with the rhizobacterium pseudomonas fluorescens pf29arp as a biocontrol agent of the fungus gaeumannomyces graminis var. tritici (ggt) on wheat roots. in parallel with the assessment of disease extension, together with the bacterial ... | 2011 | 21726382 |
| biological control of take-all by fluorescent pseudomonas spp. from chinese wheat fields. | take-all disease of wheat caused by the soilborne fungus gaeumannomyces graminis var. tritici is one of the most important root diseases of wheat worldwide. bacteria were isolated from winter wheat from irrigated and rainfed fields in hebei and jiangsu provinces in china, respectively. samples from rhizosphere soil, roots, stems, and leaves were plated onto king's medium b agar and 553 isolates were selected. on the basis of in vitro tests, 105 isolates (19% of the total) inhibited g. graminis v ... | 2011 | 22070279 |
| Enhancing plant disease suppression by Burkholderia vietnamiensis through chromosomal integration of Bacillus subtilis chitinase gene chi113. | Burkholderia vietnamiensis P418 is a plant growth-promoting rhizobacteria. A chitinase gene from Bacillus subtilis was cloned and stably integrated into the chromosome of using the transposon delivery vector, pUTkm1. Chitinase activity was detected in recombinant P418-37 but not in wild type P418. Recombinant P418-37 retained the in vitro growth rate, N(2)-fixation and phosphate and potassium-solubilizing characteristics of the wild type. P418-37 significantly (P < 0.05) inc ... | 2011 | 21972146 |