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stimulation of de novo synthesis of l-phenylalanine ammonia-lyase in relation to phytoalexin accumulation in colletotrichum lindemuthianum elicitor-treated cell suspension cultures of french bean (phaseolus vulgaris).(1) the regulation of the accumulation of the isoflavonoid-derived phytoalexin phaseollin in cell suspension cultures of dwarf french bean (phaseolus vulgaris/ has been investigated. (2) an elicitor preparation from cell walls of colletotrichum lindemuthianum, the causal agent of anthracnose disease of french bean, caused a marked accumulation of phaseollin in the cultures. the elicitor induced phaseollin accumulation to a level of 60% that obtained with the artificial elicitor autoclaved ribonu ...1979476149
degradation of 4-(2,4-dichlorophenoxy)butyric acid (2,4-db) by phytophthora megasperma. 19761254809
elicitor-specific induction of one member of the chitinase gene family in arachis hypogaea.chitinases are believed to play an important role in plant defence against bacterial and fungal attack. in peanut (arachis hypogaea) chitinase genes form a small multigene family. four chitinase cdnas (chit 1-4) were isolated from cultured peanut cells. expression of individual chit genes was assayed by the polymerase chain reaction (pcr) followed by analysis of restriction fragment length polymorphisms (rflp). uv irradiation, dilution of cell cultures and treatment with phytophthora megasperma ...19901980004
actin in the oomycetous fungus phytophthora infestans is the product of several genes.actin (act) in phytophthora infestans is encoded by at least two genes, in contrast to unicellular and other filamentous fungi where there is a single gene. these genes (designated acta and actb) have been isolated from a genomic library of p. infestans. the complete nucleotide sequence of both genes has been determined. unlike the actin-encoding genes (act) of other filamentous fungi, no introns are obvious in the coding region, a feature shared with the act genes of certain protists. northern ...19912055461
genic rearrangements in phytophthora mitochondrial dna.to assess evolutionary relationships among the oomycetous fungi we have constructed a physical and genic map of the mtdna of a broad host range strain (695t) of phytophthora megasperma. while, like other phytophthora species, this 43.5 kb circular genome lacks the typical oomycete large inverted repeat, a short 0.5-0.9 kb inverted repeat has been identified. comparison of the relative order of seven genic regions with host-specific phytophthora strains reveals both a clustering of these loci wit ...19902357738
induction of 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase activity by fungal elicitor in cultures of petroselinum crispum.the effects of a cell wall fraction of the fungus phytophthora megasperma on the enzymatic activities of 3-deoxy-d-arabino-heptulosonate-7-phosphate (dahp) synthase (ec 4.1.2.15) in extracts of cultured parsley cells (petroselinum crispum) were examined. the specific activity of a plastidic form of dahp synthase, designated ds-mn by ganson et al. [ganson, r. j., d'amato, t. a. & jensen, r. a. (1986) plant physiol. 82, 203-210], was increased 2- to 3-fold in extracts of treated cells, with maximu ...19892571991
elicitor-induced biosynthesis of psoralens in ammi majus l. suspension cultures. microsomal conversion of demethylsuberosin into (+)marmesin and psoralen.suspension cultures of ammi majus l. cells produce various linear furanocoumarins in response to treatment with elicitor preparations from either alternaria carthami chowdhury or phytophthora megasperma f.sp. glycinea. microsomes which were isolated from these cells 14 h after addition of the elicitor efficiently catalyzed the conversion of demethyl [3-14c]suberosin into labelled (+)marmesin in the presence of nadph and oxygen. in contrast to the chemical cyclization of demethylsuberosin by m-ch ...19882828055
defense strategies of soybean against the fungus phytophthora megasperma f.sp. glycinea: a molecular analysis. 19883072693
further investigations of race:cultivar-specific induction of enzymes related to phytoalexin biosynthesis in soybean roots following infection with phytophthora megasperma f.sp. glycinea.the activities of the following enzymes in soybean roots were determined at early times after infection of the roots with zoospores of an incompatible or a compatible race of phytophthora megasperma f.sp. glycinea: dimethylallyl-diphosphate : 3,6a,9-trihydroxypterocarpan dimethylallyltransferase (prenyltransferase), an enzyme specific for glyceollin biosynthesis; nadph-cytochrome reductase and hydroxymethylglutaryl-coa reductase, enzymes related to the glyceollin pathway; and isocitrate dehydrog ...19863094555
effects of ca2+ on phytoalexin induction by fungal elicitor in soybean cells.a glucan elicitor from the cell walls of the fungus phytophthora megasperma f.sp. glycinea caused increases in the activities of the phytoalexin biosynthetic enzymes, phenylalanine ammonia-lyase and chalcone synthase, and induced the production of the phytoalexin, glyceollin, in soybean (glycine max) cell suspension cultures when tested in culture medium containing 1.2 mmol/liter ca2+. removal of extracellular ca2+ by treatment with ethylene glycol bis(beta-aminoethyl ether)-n, n'-tetraacetic ac ...19873116938
biosynthesis of psoralens. psoralen 5-monooxygenase activity from elicitor-treated ammi majus cells.microsomes prepared from cultured ammi majus cells that had been challenged for 14 h with an elicitor derived from the cell walls of phytophthora megasperma f.sp. glycinea (pmg) converted psoralen to bergaptol (5-hydroxypsoralen) in the presence of nadph and oxygen. the enzymatic activity was characterized as an inducible cytochrome-p-450-dependent monooxygenase associated with the endoplasmic reticulum. all of the steps involved in bergapten (5-methoxypsoralen) biosynthesis in ammi majus have n ...19883181429
high-affinity binding of fungal beta-glucan fragments to soybean (glycine max l.) microsomal fractions and protoplasts.we have recently reported the existence of binding sites in soybean membranes for a beta-glucan fraction derived from the fungal pathogen phytophthora megasperma f. sp. glycinea, which may play a role in the elicitor-mediated phytoalexin response of this plant [schmidt, w. e. & ebel, j. (1987) proc. natl acad. sci. usa 84, 4117-4121]. the specificity of beta-glucan binding to soybean membranes has now been investigated using a variety of competing polyglucans and oligoglucans of fungal origin. p ...19883402458
enhanced instrumental sensitivity and selectivity for aminopeptidase profiling.laser-excited fluorimetry has been applied to the identification of bacteria and fungus. the instrumental sensitivity and selectivity of the aminopeptidase profiling method has been enhanced by the use of laser excitation in conjunction with improved spectral and temporal background rejection. the linear dynamic range for the aminopeptidase technique has been increased by achieving a reduced lower limit of detection of the fluorescent tag, beta-naphthylamine. standard aminopeptidase methodology ...19863706731
elicitor-induced phytoalexin synthesis in soybean cells: changes in the activity of chalcone synthase mrna and the total population of translatable mrna.rapid changes in the mrna activity encoding chalcone synthase, a central enzyme involved in isoflavonoid phytoalexin synthesis, were induced in cultured cells of soybean (glycine max) after treatment with a glucan elicitor from the cell walls of the fungus, phytophthora megasperma f. sp. glycinea, a soybean pathogen. two-dimensional gel electrophoresis of the in vitro- and in vivo-synthesized chalcone synthase showed that it consisted of a group of proteins of similar molecular weights of about ...19853855251
elicitor induction of a microsomal 5-o-(4-coumaroyl)shikimate 3'-hydroxylase in parsley cell suspension cultures.microsomal preparations from parsley cell suspension cultures challenged with an elicitor from phytophthora megasperma f.sp. glycinea (pmg) catalyze the formation of trans-5-o-caffeoylshikimate from trans-5-o-(4-coumaroyl)shikimate. neither the cis isomer nor free 4-coumarate, 4-coumaroyl-coa, or 5-o-(4-coumaroyl)quinate are substrates for this enzyme. the reaction is strictly dependent on nadph as a reducing cofactor and on molecular oxygen. nadh, ascorbic acid, and 6,7-dimethyl-5,6,7,8-tetrahy ...19854037798
the effect of calcium on mycelial growth of phytophthora megasperma and p. cinnamomi. 19685700459
immunohistochemical detection of phytophthora megasperma f. sp. glycinea in situ. 19836352265
differential response of cultured parsley cells to elicitors from two non-pathogenic strains of fungi. 1. identification of induced products as coumarin derivatives.dark-grown cell suspension cultures of parsley, petroselinum hortense, produce furanocoumarins after treatment with elicitor preparations of either phytophthora megasperma f.sp. glycinea (pmg elicitor) or alternaria carthami chowdhury (ac elicitor). the linear furanocoumarins, psoralen and xanthotoxin, and the benzodipyrandione, graveolone, are the major products synthesized in response to pmg elicitor, besides small amounts of the furanocoumarin bergapten. treatment with ac elicitor induces pre ...19836682038
investigation of the mechanism of glyceollin accumulation in soybean infected by phytophthora megasperma f. sp. glycinea. 19817034651
a new elicitor of the hypersensitive response in tobacco: a fungal glycoprotein elicits cell death, expression of defence genes, production of salicylic acid, and induction of systemic acquired resistance.a 32 kda glycoprotein whose effects in tobacco and other nicotianae mimic a typical hypersensitive response, was isolated from phytophthora megasperma. infiltration of a few nanograms of the protein into leaves caused the formation of lesions that closely resemble hypersensitive response lesions. transcripts of genes encoding enzymes of the phenylpropanoid and sesquiterpenoid pathways accumulated rapidly after elicitor application followed by salicylic acid production. cellular damage, restricte ...19957496401
perception and transduction of an elicitor signal in cultured parsley cells.treatment of cultured parsley cells or protoplasts with a purified extracellular glycoprotein from phytophthora megasperma f.sp. glycinea induces the transcription of the same set of defence-related genes as is activated in parsley leaves upon infection. elicitor activity was shown to reside in a specific portion of the protein moiety which was isolated, sequenced and synthesized. partial cdnas encoding the entire mature protein as well as other related proteins have been isolated, indicating th ...19947639778
cytosolic protons as secondary messengers in elicitor-induced defence responses.a variety of early elicitor-induced membrane responses have been described, and their possible role in the generation of second messengers involved in the cascades of events leading to the activation of defence genes is actively investigated. treatment of tobacco cells with a crude elicitor preparation from phytophthora megasperma, purified oligouronides and a commercial pectate lyase, induce a common set of membrane reactions similar to those described in a variety of plant material, i.e. efflu ...19947639771
oligopeptide elicitor-mediated defense gene activation in cultured parsley cells.we have used suspension-cultured parsley cells (petroselinum crispum) and an oligopeptide elicitor derived from a surface glycoprotein of the phytopathogenic fungus phytophthora megasperma f.sp. glycinea to study the signaling pathway from elicitor recognition to defense gene activation. immediately after specific binding of the elicitor by a receptor in the plasma membrane, large and transient increases in several inorganic ion fluxes (ca2+, h+, k+, cl-) and h2o2 formation are the first detecta ...19957753777
characterization of hepta-beta-glucoside elicitor-binding protein(s) in soybean.we are studying the cellular signalling pathway leading to pterocarpan phytoalexin biosynthesis in soybean that is induced by a branched hepta-beta-glucoside originally isolated from the mycelial walls of the phytopathogenic oomycete, phytophthora megasperma f. sp. glycinea. our research has focused on the first step in this signal pathway, namely the specific recognition of the hepta-beta-glucoside elicitor by plasma-membrane-localized binding protein(s) in soybean cells. binding of a radio-iod ...19947639770
molecular cloning and expression of a new class of ortho-diphenol-o-methyltransferases induced in tobacco (nicotiana tabacum l.) leaves by infection or elicitor treatment.in tobacco (nicotiana tabacum l. cv samsun nn), three distinct enzymes account for ortho-diphenol-o-methyltransferase (omt) activity. omt i is the major enzyme of healthy leaves, whereas enzymes omt ii and iii are preferentially induced during the hypersensitive reaction to tobacco mosaic virus (tmv). using an anti-omt iii antiserum, we isolated a partial omt iii cdna clone by immunoscreening an expression library made from mrna of tmv-infected tobacco leaves. using this omt iii clone as a probe ...19937518088
structural features of fungal beta-d-glucans for the efficient inhibition of the initiation of virus infection on nicotiana tabacum.glucans of fungal origin have been shown to inhibit the early stages of infection of nicotiana by numerous viruses of different taxonomic groups. several glucans were isolated from the cell walls of phytophthora parasitica, phytophthora megasperma f. sp. glycinea (pmg) and fusarium oxysporum, and their antiviral activity compared on tobacco leaves inoculated with tobacco mosaic virus. these polysaccharides consist of a mixture of (1-->3)(1-->6)-beta-d-glucans with m(r) varying from 1.1 x 10(3) t ...19957786491
molecular characterization of nucleotide sequences encoding the extracellular glycoprotein elicitor from phytophthora megasperma.cdna sequences encoding the 42 kda glycoprotein elicitor from the oomycete, phytophthora megasperma, that induces the defense response in parsley have been cloned and sequenced. the 5' end of the mrna matches a consensus derived from sequences surrounding the transcription initiation sites of seven other oomycete genes. the major transcript of 1802 nucleotides contains a 529-codon open reading frame, which was predicted to encode a 57 kda precursor protein. on the basis of peptide sequencing, th ...19957823912
importance of antibiotic production in antagonism of selected streptomyces species to two soil-borne plant pathogens.antagonism of ten streptomyces spp., five of which produce antibiotics, to the plant pathogens rhizoctonia solani and phytophthora megasperma var. sojae was studied. antibiotic activity was detected in culture for the five antibiotic producers. s. griseus, s. hygroscopicus var. geldanus, and s. noursei produced wide zones of inhibition to r. solani and p. megasperma var. sojae. similar activity was found for s. reticuli var. protomycicus to p. megasperma var. sojae. s. cellulosae reduced rhizoct ...19817287585
induction and characterization of a microsomal flavonoid 3'-hydroxylase from parsley cell cultures.a microsomal preparation from irradiated parsley cell cultures catalyses the nadph and dioxygen-dependent hydroxylation of (s)-naringenin [(s)-5, 7, 4'-trihydroxyflavanone] to eriodictyol (5, 7, 3', 4'-tetrahydroxyflavanone). dihydrokaempferol, kaempferol, and apigenin were also substrates for the 3'-hydroxylase reaction. in contrast prunin (naringenin 7-o-beta-glucoside) was not converted by the enzyme. the microsomal preparation, which also contains cinnamate 4-hydroxylase, did not catalyse hy ...19836884346
differential response of cultured parsley cells to elicitors from two non-pathogenic strains of fungi. 2. effects on enzyme activities.parsley cell cultures produce linear furanocoumarins and the linear benzodipyrandione, graveolone, in response to treatment with an elicitor from either phytophthora megasperma or alternaria carthami. activities of enzymes involved in general phenylpropanoid metabolism, phenylalanine ammonia-lyase and 4-coumarate: coa ligase, as well as of an enzyme involved specifically in furanocoumarin biosynthesis, dimethylallyl diphosphate: umbelliferone dimethylallyltransferase, were monitored over several ...19836682039
the primary structures of one elicitor-active and seven elicitor-inactive hexa(beta-d-glucopyranosyl)-d-glucitols isolated from the mycelial walls of phytophthora megasperma f. sp. glycinea.the primary structures of eight hexa(beta-d-glucopyranosyl)-d-glucitols purified from partially hydrolyzed phytophthora megasperma f. sp. glycinea mycelial walls were determined by microscale glycosyl-sequence analysis. the elicitor-active hexa(beta-d-glucopyranosyl)-d-glucitol had the following structure: (formula: see text) the similarity in structure of six of the elicitor-inactive hexa(beta-d-glucopyranosyl)-d-glucitols to the elicitor-active hexa(beta-d-glucopyranosyl)-d-glucitol establishe ...19846470003
race:cultivar-specific induction of enzymes related to phytoalexin biosynthesis in soybean roots following infection with phytophthora megasperma f. sp. glycinea.primary roots of soybean [glycine max (l.), cv harosoy 63] seedlings were inoculated with zoospores from either race 1 (incompatible, host resistant) or race 3 (compatible, host susceptible) of phytophthora megasperma f. sp. glycinea (pmg) and the activities of phenylalanine ammonia-lyase (pal), chalcone synthase (chs), isoflavone synthase, and dihydroxypterocarpan 6a-hydroxylase related to phytoalexin (glyceollin) biosynthesis, and of glucose-6-phosphate dehydrogenase (glc-6-pdh) and glutamate ...19863963819
structure of the large ribosomal subunit rna of phytophthora megasperma, and phylogeny of the oomycetes.the 5.8s and 28s rrna sequences of the oomycete phytophthora megasperma were determined in order to study the secondary structure of these molecules and to assess the phylogenetic position of the oomycetes among the eukaryotes. preliminary results point to an affiliation between the oomycetes, dinoflagellates and ciliates, a cluster which seems related to the fungi. in the course of this work, we developed a set of primers which allow sequencing and pcr amplification of eukaryotic large ribosoma ...19948307170
transformation of the oomycete pathogen phytophthora megasperma f. sp. glycinea occurs by dna integration into single or multiple chromosomes.a procedure for stable transformation was developed for phytophthora megasperma f. sp. glycinea, an oomycete pathogen of soybean. transformants were obtained using a bacterial hygromycin resistance gene fused to a promoter and terminator from the ham34 gene of another oomycete, bremia lactucae. vector dna, alone or complexed to cationic liposomes, was introduced into protoplasts using polyethylene glycol and cacl2. dna and rna hybridization, and phosphotransferase assays, confirmed the presence ...19938382110
a structural model for the mechanisms of elicitor release from fungal cell walls by plant beta-1,3-endoglucanase.the release of elicitor-active carbohydrates from fungal cell walls by beta-1,3-endoglucanase contained in host tissues has been implicated as one of the earliest processes in the interaction between soybean (glycine max) and the fungal pathogen phytophthora megasperma f. sp. glycinea leading to host defense responses such as phytoalexin production. the present study was conducted to evaluate the primary structure of the glucanase-released elicitor (re). gel-filtration chromatography of carbohyd ...19958552716
isolation of sealed plasma membrane vesicles from phytophthora megasperma f. sp. glycinea: ii. partial characterization of ca2+ transport and glyceollin effects.calcium uptake was examined in sealed plasma membrane vesicles isolated from the plant pathogenic fungus, phytophthora megasperma f. sp. glycinea. calcium uptake was atp-dependent and by the addition of various ionophores in the presence of atp, it was shown that ca2+ transport was mediated by a nh+/ca2+ antiport. further evidence for this antiport mechanism included ca2+ uptake driven by an imposed ph gradient and the observation that calcium could dissipate a steady-state ph gradient across th ...19883142364
differential response of cultured parsley cells to elicitors from two non-pathogenic strains of fungi. microsomal conversion of (+)marmesin into psoralen.microsomal fractions isolated from parsley cell suspension cultures, which had been challenged with an elicitor from either alternaria carthami or phytophthora megasperma f. sp. glycinea, catalyzed the formation of psoralen from synthetic [3-14c](+)marmesin. whereas psoralen was the only product formed in incubations with alternaria-induced microsomes, another unidentified product was isolated from incubations with phytophthora-induced microsomes. the latter product is neither a precursor nor a ...19863023094
formation of trans-caffeoyl-coa from trans-4-coumaroyl-coa by zn2+-dependent enzymes in cultured plant cells and its activation by an elicitor-induced ph shift.a novel hydroxylase activity catalyzing the formation of trans-caffeoyl-coa from trans-4-coumaroyl-coa was identified in crude extracts from cultured parsley cells. the extracts were less active (vmax/km) in converting trans-4-coumaric to trans-caffeic acid. optimal hydroxylase activity was found at ph 6.5 with a steep decline toward both ph 7.4 and ph 5.0. the enzyme activity requires ascorbate and zn2+ at optimal concentrations of 50 and 0.5 mm, respectively. no other reductant could replace a ...19892919878
differential expression of eight chitinase genes in medicago truncatula roots during mycorrhiza formation, nodulation, and pathogen infection.expression of eight different chitinase genes, representing members of five chitinase classes, was studied in medicago truncatula roots during formation of arbuscular mycorrhiza with glomus intraradices, nodulation with rhizobium meliloti, and pathogen attack by phytophthora megasperma f. sp. medicaginis, fusarium solani f. sp. phaseoli (compatible interactions with root rot symptoms), ascochyta pisi (compatible, symptomless), and f. solani f. sp. pisi (incompatible, nonhost interaction). in the ...200010875337
isolation of sealed plasma membrane vesicles from phytophthora megasperma f. sp. glycinea. i. characterization of proton pumping and atpase activity.sealed vesicles were isolated from a plant pathogenic fungus phytophthora megasperma f. sp. glycinea using a modification of a method previously developed for plant plasma membrane vesicle isolation. vanadate-sensitive, proton pumping microsomal membrane vesicles were resolved on a linear sucrose density gradient and found to comigrate with a vanadate-sensitive atpase. both the proton pumping and atpase activity of these vesicles had a ph optimum of 6.5 and demonstrated similar properties with r ...19882844118
the biosynthesis of phytoalexins in dianthus caryophyllus l. cell cultures: induction of benzoyl-coa:anthranilate n-benzoyltransferase activity.it has been shown that cell cultures of dianthus caryophyllus l. c.v. eleganz accumulate n-benzoyl-4-methoxyanthranilic acid, previously identified as the phytoalexin methoxydianthramide b, in response to treatment either with a crude elicitor isolated from the cell walls of phytophthora megasperma f.sp. glycinea or with a commercial yeast extract. cell-free extracts from the induced cells efficiently catalyzed the n-benzoylation of anthranilate in the presence of benzoyl-coa. the partially puri ...19892817901
a novel tetratricopeptide repeat-containing j-protein localized in a plasma membrane-bound protein complex of the phytopathogenic oomycete phytophthora megasperma.phytoalexins originating from plant tissues may cause within cells of fungi or oomycetes a change in the localization of actin, tubulin and chaperones. to test the hypothesis in a filamentously growing oomycete, we compared the distribution of cellular markers in the presence and absence of hydroxystilbene phytoalexins. using cdna from the phytopathogenic organism phytophthora megasperma, the causal agent of root rot on soybean and many other plants, and including probes for hsp70 and hsp40, we ...200111561904
formation of di-isodityrosine and loss of isodityrosine in the cell walls of tomato cell-suspension cultures treated with fungal elicitors or h2o2.about 84% of the hydroxyproline residues in a cell culture of tomato (lycopersicon esculentum x lycopersicon peruvianum) were present in phenol-inextractable (i.e. covalently wall-bound) material. treatment of the cells with any of three fungal elicitors (wall fragments from phytophthora megasperma and pythium aphanidermatum and xylanase from aureobasidium pullulans) or with 1 mm h2o2 had little effect on the quantity of phenolinextractable hydroxyproline per milligram of freeze-dried cells. how ...199712223793
conditioning of parsley (petroselinum crispum l.) suspension cells increases elicitor-induced incorporation of cell wall phenolics.the elicitor-induced incorporation of phenylpropanoid derivatives into the cell wall and the secretion of soluble coumarin derivatives (phytoalexins) by parsley (petroselinum crispum l.) suspension cultures can be potentiated by pretreatment of the cultures with 2,6-dichloroisonicotinic acid or derivatives of salicylic acid. to investigate this phenomenon further, the cell walls and an extracellular soluble polymer were isolated from control cells or cells treated with an elicitor from phytophth ...199312231833
phytoalexin synthesis in soybean cells: elicitor induction of reductase involved in biosynthesis of 6'-deoxychalcone.chromatofocusing on mono p proved to be an efficient purification procedure for the nadph-dependent reductase from soybean (glycine max l.) cell cultures which acts together with chalcone synthase in the biosynthesis of 2',4',4-trihydroxychalcone (6'-deoxychalcone). by isoelectric focusing the pi of reductase was determined to be 6.3. addition of pure soybean reductase to cell-free extracts from stimulated cell cultures of parsley and bean (phaseolus vulgaris) and from young flowers of dahlia va ...19892500065
high-affinity binding of a synthetic heptaglucoside and fungal glucan phytoalexin elicitors to soybean membranes.soybean membranes possess high-affinity binding sites for fungal beta-glucans that elicit phytoalexin synthesis. the ability of 1,3-1,6-beta-glucans, released by acid hydrolysis from mycelial walls of phytophthora megasperma f.sp. glycinea, to compete for the putative phytoalexin elicitor receptors increases with their average degree of polymerization (dp). the results suggest a function where the probability for glucan fragments of containing a structural determinant that is optimal for binding ...19902226806
immediate activation of respiration in petroselinum crispum l. in response to the phytophthora megasperma f. sp. glycinea elicitor.treatment of parsley (petroselinum crispum l.) cell cultures with the phytophthora megasperma elicitor isolated from the fungus phytophthora megasperma f. sp. glycinea caused an immediate increase in the rate of respiratory co2 evolution in the dark. the respiratory response was biphasic, showing a rapid enhancement in the first 20 min and then a slower increase until a steady rate was attained 60 min posttreatment. the enhanced rate of co2 evolution corresponded to the activation of phosphofruc ...199412232429
temporal and spatial patterns of gene expression around sites of attempted fungal infection in parsley leaves.we analyzed the expression patterns of several pathogen defense-related genes in primary leaf buds of parsley by in situ rna hybridization. labeled antisense rna probes were generated from seven selected cdnas detecting transcripts from genes that are rapidly and strongly activated in cultured parsley cells upon treatment with fungal elicitor. these genes encode two enzymes of general phenylpropanoid metabolism, phenylalanine ammonia-lyase and 4-coumarate:coa ligase, a furanocoumarin-specific be ...198912359883
the single-copy actin gene of phytophthora megasperma encodes a protein considerably diverged from any other known actin.this paper reports the cloning and sequencing of a phytophthora megasperma actin gene. sequence analysis revealed that the gene does not contain introns and encodes a putative actin protein remarkably diverged from any other known actins. genomic southern analysis indicates that there is a single actin gene per haploid genome, which is actively transcribed in vivo, as revealed by s1 mapping of the transcripts. the transcripts are heterogeneous in size because they have different 3' termini, none ...19902102822
isoflavonoid-inducible resistance to the phytoalexin glyceollin in soybean rhizobia.the antibacterial effect of the soybean phytoalexin glyceollin was assayed using a liquid microculture technique. log-phase cells of bradyrhizobium japonicum and sinorhizobium fredii were sensitive to glyceollin. as revealed by growth rates and survival tests, these species were able to tolerate glyceollin after adaptation. incubation in low concentrations of the isoflavones genistein and daidzein induced resistance to potentially bactericidal concentrations of glyceollin. this inducible resista ...19912045365
purification and properties of invertases extractable from phytophthora megasperma var. sojae mycelia. 19807396503
a molecular phylogeny of pythium insidiosum.sequence analysis of the ribosomal dna internal transcribed spacers (its) was used to establish phylogenetic relationships among 23 isolates of pythium insidiosum, the etiological agent of pythiosis in mammals. the isolates were divided into three distinct clades that exhibited significant geographic isolation. clade i consisted of isolates from north, central, and south america, while clade ii contained isolates from asia and australia. also present in clade ii was an isolate from a patient in ...200312884950
enzyme induction in soybean infected by phytophthora megasperma f.sp. glycinea. 19826889840
sterol induction of reproduction and stimulation of growth of pythium and phytophthora.sterols of fungal, plant, and animal origin induced sexual reproduction in pythium periplocum and phytophthora megasperma var. sojae and the formation of large zoosporangia in phytophthora parasitica var. nicotianae. some sterols, especially cholesterol, stimulated growth.196414137942
modeling the qo site of crop pathogens in saccharomyces cerevisiae cytochrome b.saccharomyces cerevisiae has been used as a model system to characterize the effect of cytochrome b mutations found in fungal and oomycete plant pathogens resistant to q(o) inhibitors (qois), including the strobilurins, now widely employed in agriculture to control such diseases. specific residues in the q(o) site of yeast cytochrome b were modified to obtain four new forms mimicking the q(o) binding site of erysiphe graminis, venturia inaequalis, sphaerotheca fuliginea and phytophthora megasper ...200415153117
synthesis of a glucoheptaose and a glucooctaose that elicit phytoalexin accumulation in soybean.the glucoheptaose 1 and the glucooctaose 2 have been synthesized using unambiguous methods. the former is identical with an elicitor-active heptasaccharide obtained from partially hydrolyzed mycelium of phytophthora megasperma f. sp. glycinea. the octasaccharide is also elicitor active, although to a lesser extent than the heptasaccharide. 1:r = h; 2:r = beta-d-glcp. (formula: see text)19846540779
purification and partial characterization of a beta-glucan fragment that elicits phytoalexin accumulation in soybean.the synthesis of phytoalexins (antibiotics) in plant cells is induced by molecules called elicitors. partial acid hydrolysis of mycelial walls of phytophthora megasperma f. sp. glycinea solubilized a multicomponent mixture of elicitor-active and elicitor-inactive oligoglucosides. one elicitor-active and seven elicitor-inactive hexa(beta-d-glucopyranosyl)-d-glucitols were purified by gel-filtration, normal-phase partition, and reversed-phase liquid chromatography after reduction with nabh4. the e ...19846540778
induction and suppression of phytoalexin biosynthesis in cultured cells of safflower, carthamus tinctorius l., by metabolites of alternaria carthami chowdhury.cell suspension cultures derived from the safflower variety us-10 respond to treatment with cell wall elicitors from either phytophthora megasperma f.sp.glycinea or alternaria carthami chowdhury by producing polyacetylenic phytoalexins. these polyacetylenes were absent from the uninduced cell cultures. low concentrations of brefeldin a, a toxin produced by a. carthami, when added to suspension-cultured safflower cells, considerably diminished the accumulation of the phytoalexins following elicit ...19846538399
induction of phenylalanine ammonia-lyase and 4-coumarate:coa ligase mrnas in cultured plant cells by uv light or fungal elicitor.the mrnas encoding two enzymes of phenylpropanoid metabolism, phenylalanine ammonia-lyase (pal; ec 4.3.1.5) and 4-coumarate:coa ligase (4cl; ec 6.2.1.12), were induced in cultured parsley cells (petroselinum hortense) either by irradiation with uv light or by treatment with elicitor, a cell-wall fraction of the fungus phytophthora megasperma f. sp. glycinea. two-dimensional gel electrophoresis of the encoded pal and 4cl proteins revealed that the mrnas induced by either treatment were very simil ...198416593418
rapid activation by fungal elicitor of genes encoding "pathogenesis-related" proteins in cultured parsley cells.administration of a cell-wall preparation from the fungus phytophthora megasperma f. sp. glycinea, which acts as an elicitor of phytoalexin production in cell suspension cultures of parsley (petroselinum crispum), also results in a rapid and dramatic increase in the relative amounts of mrnas coding for a number of small proteins having low isoelectric points. according to various operational criteria, the translation products are classified as "pathogenesis-related" (pr) proteins. here we report ...198616593684
induction of phytoalexin synthesis in soybean: enzymatic cyclization of prenylated pterocarpans to glyceollin isomers.a microsome preparation from elicitor-challenged soybean cell suspension cultures catalyzed an nadph-dependent and oxygen-dependent cyclization of a mixture of 2- and 4-dimethylallylglycinols to the glyceollin isomers i-iii. this is the last committed step in glyceollin biosynthesis. the cyclase was inhibited in a light-reversible manner by carbon monoxide in the presence of oxygen. cyclase was also inhibited by cytochrome c, nadp+, and a number of inhibitors of cytochrome p-450 enzymes. nadh in ...19883369863
amino acid sequence of the alpha-elicitin secreted by phytophthora cactorum.elicitins are toxic, signalling proteins secreted by phytophthora spp. responsible for the incompatible reaction and systemic leaf necroses. we have sequenced the least toxic known elicitin, which is secreted by phytophthora cactorum and belongs to the alpha-elicitin class. this 98 residue sequence was compared to eight other known elicitins. in addition to the point mutation already observed to correlate with the differences in necrotic activities, we confirmed the existence of amino acid chang ...19937764283
phytoalexin synthesis in soybean cells: elicitor induction of phenylalanine ammonia-lyase and chalcone synthase mrnas and correlation with phytoalexin accumulation.a glucan elicitor from cell walls of the fungus phytophthora megasperma f. sp. glycinea, a pathogen of soybean (glycine max), induced large and rapid increases in the activities of enzymes of general phenylpropanoid metabolism, phenylalanine ammonia-lyase, and of the flavonoid pathway, acetyl-coa carboxylase and chalcone synthase, in suspension-cultured soybean cells. the changes in phenylalanine ammonia-lyase and chalcone synthase activities were correlated with corresponding changes in the mrn ...19846540068
molecular cloning and heterologous expression of acridone synthase from elicited ruta graveolens l. cell suspension cultures.cell suspension cultures of ruta graveolens l. produce a variety of acridone alkaloids, and the accumulation can be stimulated by the addition of fungal elicitors. acridone synthase, the enzyme catalyzing the synthesis of 1,3-dihydroxy-n-methylacridone from n-methylanthraniloyl-coa and malonyl-coa, had been isolated from these cells, and the partial enzyme polypeptide sequence, elucidated from six tryptic fragments, revealed homology to heterologous chalcone synthases. poly(a)+ rna was isolated ...19957727746
sequences of acidic and basic elicitin isoforms secreted by phytophthora megasperma megasperma.elicitins are toxic proteins secreted by phytophthora spp. responsible for the incompatible reaction and systemic leaf necroses on tobacco. we found that phytophthora megasperma megasperma produces two elicitin isoforms, each belonging to a different physico-chemical class, although the beta elicitin was less toxic than other beta ones. these 98 residue proteins were purified, sequenced and compared with other known elicitins. in addition to the point mutation already known to correlate with the ...19937763784
covalent cross-linking of the phytophthora megasperma oligopeptide elicitor to its receptor in parsley membranes.an oligopeptide elicitor from phytophthora megasperma f.sp. glycinea (pep-13) that induces phytoalexin accumulation in cultured parsley cells was radioiodinated and chemically cross-linked to its binding site in microsomal and plasma membrane preparations with each of three homobifunctional reagents. analysis by sds/page and autoradiography of solubilized membrane proteins demonstrated labeling of a 91-kda protein, regardless of which reagent was used. cross-linking of this protein was prevented ...19957892267
sequence analysis of duplicated actin genes in lagenidium giganteum and pythium irregulare (oomycota).southern analysis of genomic dna identified multiple-copy actin gene families in lagenidium giganteum and pythium irregulare (oomycota). polymerase chain reaction (pcr) protocols were used to amplify members of these actin gene families. sequence analysis of genomic coding regions demonstrated five unique actin sequences in l. giganteum (lg-ac1, 2, 3, 4, 5) and four unique actin sequences in p. irregulare (pi-ac1, 2, 3, 4); none were interrupted by introns. maximum parsimony analysis of the codi ...19948064873
hsp90 homologue from madagascar periwinkle (catharanthus roseus): cdna sequence, regulation of protein expression and location in the endoplasmic reticulum.we describe cdnas for a hsp90 homologue from catharanthus roseus and studies on the regulation of expression. the largest cdna (2670 bp) coded for a protein of 817 amino acids with a calculated size of 93,491 da and a pi of 4.61. it contained a eucaryotic secretory signal, the endoplasmic reticulum (er) targeting and retention signal (lys-asp-glu-leu), and the hsp90 protein family signature with one conservative exchange (asn-lys-asp-ile-phe-leu instead of asn-lys-glu-ile-phe-leu). rna blots rev ...19938106014
activation of a tobacco glycine-rich protein gene by a fungal glucan preparation.a phytophthora megasperma f.sp. glycinea cell wall glucan preparation was previously shown to protect tobacco plants against viral infection. eleven plant defense-related genes were assayed for elevated mrna accumulation levels in response to glucan treatment of tobacco plants. the expression of only one of these genes, a glycine-rich protein (grp) gene, was induced by glucan application. elevated grp gene mrna levels could be detected within 15 min of glucan treatment and reached maximum levels ...19938220493
molecular cloning and expression of 4-coumarate:coenzyme a ligase, an enzyme involved in the resistance response of soybean (glycine max l.) against pathogen attack.we have isolated three classes of cdnas that probably encode three 4-coumarate:coenzyme a ligase (4cl) isoenzymes in soybean (glycine max l.). the deduced amino acid sequences reveal several regions of extended sequence identity among 4cls of all plants analyzed to date. the sequences of two of these regions are consistent with a domain structure proposed for a group of enzymes catalyzing the atp-dependent covalent binding of amp to their substrates during the reaction sequence. by using two cdn ...19938278545
rapid response of suspension-cultured parsley cells to the elicitor from phytophthora megasperma var. sojae: induction of the enzymes of general phenylpropanoid metabolism.large and rapid increases in the activities of two enzymes of general phenylpropanoid metabolism, phenylalanine ammonia-lyase and 4-coumarate:coa ligase, occurred in suspension-cultured parsley cells (petroselinum hortense) treated with an elicitor preparation from phytophthora megasperma var. sojae. highest enzyme activities were obtained with an elicitor concentration similar to that required for maximal phenylalanine ammonialyase induction in cell suspension cultures of soybean, a natural hos ...198116661752
aquatic fungi of the narew river and its tributaries in the stretch from siemianówka to doktorce.the work was undertaken to investigate the mycoflora of the lowland river narew and its tributaries in the stretch from siemianówka to doktorce. samples of water collected once a month over the years 1987-1991 for hydrochemical analysis and studies of the stretch from siemianówka to doktorce. the following fungi unknown from poland were found in this rivers: dangeardia laevis. lagenidium rabenhorstii, olpidiopsis achlyae, phytophthora megasperma, phytophthora gonapodyoides, pythium akanense, tri ...19969020536
cyclic [beta]-1,6-1,3-glucans of bradyrhizobium japonicum usda 110 elicit isoflavonoid production in the soybean (glycine max) host.high levels of cyclic [beta]-1,6-1,3-glucans (e.g. 0.1 mg mg-1 of total protein) are synthesized by free-living cells as well as by bacteroids of bradyrhizobium japonicum usda 110 (k.j. miller, r.s. gore, r. johnson, a.j. benesi, v.n. reinhold [1990] j bacteriol 172: 136-142; r.s. gore and k.j. miller [1993] plant physiol 102: 191-194). these molecules share structural features with glucan fragments isolated from the mycelial cell wall of the soybean (glycine max) pathogen phytophthora megasperm ...199412232136
molecular cloning and biological activity of alpha-, beta-, and gamma-megaspermin, three elicitins secreted by phytophthora megasperma h20.we report on the molecular cloning of the phytophthora megasperma h20 (pmh20) glycoprotein shown previously as an inducer of the hypersensitive response, of localized acquired resistance and of systemic acquired resistance in tobacco (nicotiana tabacum), and of the pmh20 alpha- and beta-megaspermin, two elicitins of class i-a and i-b, respectively. the structure of the glycoprotein shows a signal peptide of 20 amino acids followed by the typical elicitin 98-amino acid-long domain and a 77-amino ...200312529524
a harpin binding site in tobacco plasma membranes mediates activation of the pathogenesis-related gene hin1 independent of extracellular calcium but dependent on mitogen-activated protein kinase activity.harpin from the bean halo-blight pathogen pseudomonas syringae pv phaseolicola (harpin(psph)) elicits the hypersensitive response and the accumulation of pathogenesis-related gene transcripts in the nonhost plant tobacco. here, we report the characterization of a nonproteinaceous binding site for harpin(psph) in tobacco plasma membranes, which is assumed to mediate the activation of plant defense responses in a receptor-like manner. binding of 125i-harpin(psph) to tobacco microsomal membranes (d ...200111340183
host-pathogen interactions: xii. response of suspension-cultured soybean cells to the elicitor isolated from phytophthora megasperma var. sojae, a fungal pathogen of soybeans.the glucan elicitor isolated from the mycelial walls of phytophthora megasperma var. sojae, the fungus which causes stem and root rot in soybeans, stimulates the activity of phenylalanine ammonia-lyase and the accumulation of glyceollin in suspension-cultured soybean cells. nigeran, a commercially available fungal wall glucan, was the only other compound tested which has any activity in this system. glyceollin is a phenylpropanoid-derived phytoalexin which is toxic to p. megasperma var. sojae. e ...197616659568
host-pathogen interactions: x. fractionation and biological activity of an elicitor isolated from the mycelial walls of phytophthora megasperma var. sojae.an elicitor of phytoalexin production in soybean (glycine max l.) tissues was isolated from purified phytophthora megasperma var. sojae mycelial walls by a heat treatment similar to that used to solubilize the surface antigens from the cell walls of saccharomyces cerevisiae. the wall-released elicitor is a discrete, minor portion of the p. megasperma var. sojae mycelial walls. the elicitor released from the mycelial walls was divided by diethylaminoethylcellulose and concanavalin a-sepharose chr ...197616659566
host-pathogen interactions: xi. composition and structure of wall-released elicitor fractions.the structures of the four wall-released elicitor fractions isolated from the phytophthora megasperma var. sojae mycelial walls have been examined. the results demonstrate that fraction i is primarily composed of a branched beta-1,3-glucan, similar in structure to the extracellular elicitors described previously (ayers, a., j. ebel, f. finelli, n. burger, and p. albersheim. 1976. plant physiol. 57: 751-759). fractions ii and iv are primarily composed of a highly branched mannan-containing glycop ...197616659567
specific binding of a fungal glucan phytoalexin elicitor to membrane fractions from soybean glycine max.treatment of soybean tissues with elicitors results in the production of phytoalexins, one of a number of inducible plant defense reactions against microbial infections. the present study uses a beta-1,3-[(3)h]glucan elicitor fraction from phytophthora megasperma f. sp. glycinea, a fungal pathogen of soybean, to identify putative elicitor targets in soybean tissues. use of the radiolabeled elicitor disclosed saturable high-affinity elicitor binding site(s) in membrane fractions of soybean roots. ...198716593852
host-pathogen interactions: ix. quantitative assays of elicitor activity and characterization of the elicitor present in the extracellular medium of cultures of phytophthora megasperma var. sojae.resistance of soybean (glycine max l.) seedlings to phytophthora megasperma var. sojae (pms) is in part due to the accumulation in infected tissue of a compound which is toxic to pms. the accumulation of this compound, a phytoalexin called glyceollin, is triggered by infection, but it can also be triggered by molecules, "elicitors," present in cultures of pms. the ability of the pms elicitor to stimulate phytoalexin accumulation in soybean tissues has been used as the basis for biological assays ...197616659565
hydrogen peroxide from the oxidative burst is neither necessary nor sufficient for hypersensitive cell death induction, phenylalanine ammonia lyase stimulation, salicylic acid accumulation, or scopoletin consumption in cultured tobacco cells treated with elicitin.h(2)o(2) from the oxidative burst, cell death, and defense responses such as the production of phenylalanine ammonia lyase (pal), salicylic acid (sa), and scopoletin were analyzed in cultured tobacco (nicotiana tabacum) cells treated with three proteinaceous elicitors: two elicitins (alpha-megaspermin and beta-megaspermin) and one glycoprotein. these three proteins have been isolated from phytophthora megasperma h20 and have been previously shown to be equally efficient in inducing a hypersensit ...199910482671
free and conjugated benzoic acid in tobacco plants and cell cultures. induced accumulation upon elicitation of defense responses and role as salicylic acid precursors.salicylic acid (sa) is a key endogenous component of local and systemic disease resistance in plants. in this study, we investigated the role of benzoic acid (ba) as precursor of sa biosynthesis in tobacco (nicotiana tabacum cv samsun nn) plants undergoing a hypersensitive response following infection with tobacco mosaic virus or in tobacco cell suspensions elicited with beta-megaspermin, an elicitor from phytophthora megasperma. we found a small pool of conjugated ba in healthy leaves and untre ...200111154339
defense responses in infected and elicited cucumber (cucumis sativus l.) hypocotyl segments exhibiting acquired resistance.segments from dark-grown cucumber (cucumis sativus l.) hypocotyls were used to study defense reactions occurring upon fungal infection and induced by elicitors in the same tissue. the segments were rendered resistant to infection by colletotrichum lagenarium either by growing the seedlings in the presence of dichloroisonicotinic acid (dcia) or by preincubation of the cut segments with dcia, salicylic acid (sa), or 5-chlorosalicylic acid (5csa). this resistance appears to be due mainly to inhibit ...199412232291
an extracellular protein from phytophthora parasitica var nicotianae is associated with stress metabolite accumulation in tobacco callus.the most abundant extracellular protein produced by phytophthora parasitica var nicotianae at early stages of rapid growth in culture has a molecular weight of 46 kilodaltons and has been designated ppn 46e. culture conditions for the production of this protein have been optimized and the protein has been purified by gel filtration and ion-exchange chromatography. ppn 46e is a soluble, acidic protein (pi 4.67). the amino acids asx (aspartic acid or asparagine), alanine, glycine, glx (glutamic ac ...198716665769
host-pathogen interactions : xx. biological variation in the protection of soybeans from infection by phytophthora megasperma f. sp. glycinea.phytophthora megasperma f.sp. glycinea, which causes soybean (glycine max) root and stem rot, exists as several races which differ in their ability to infect a range of soybean cultivars. a glycoprotein-rich fraction (fraction i) isolated from fungal culture fluid protects soybean seedlings from infection with compatible races. in an early study (13), seedlings were protected only by fraction i purified from incompatible races. in 1979, seedlings were better protected by fraction i isolated from ...198216662342
biological and molecular comparison between localized and systemic acquired resistance induced in tobacco by a phytophthora megasperma glycoprotein elicitin.we have compared localized (lar) and systemic (sar) acquired resistance induced in tobacco by a hypersensitive response (hr) inducing phytophthora megasperma glycoprotein elicitin. three different zones were taken into account: lar, sar(t) and sar(s). the lar zone was 5-10 mm wide and surrounded the hr lesion. sar(t) was the tissue of the elicitor-treated leaf immediately beyond the lar zone. the systemic leaf was called sar(s). glycoprotein-treated plants showed enhanced resistance to challenge ...200312602895
host-pathogen interactions: xiii. extracellular invertases secreted by three races of a plant pathogen are glycoproteins which possess different carbohydrate structures.the invertase present in the culture fluid of races 1, 2, and 3 of phytophthora megasperma drechs. var. sojae a. a. hildebrand (pms) were purified until they gave but a single band, whether stained for protein or carbohydrate, after isoelectric focusing in flat bed gels. the sugar compositions of multiple preparations of the purified invertases from each race of this fungal pathogen were determined by quantitative gas chromatography of their alditol acetates. the invertases are composed of about ...197716660002
elicitor-inducible caffeoyl-coenzyme a 3-o-methyltransferase from petroselinum crispum cell suspensions : purification, partial sequence, and antigenicity.parsley (petroselinum crispum) cell cultures respond rapidly to treatment with fungal elicitor by the accumulation of coumarin phytoalexins in the culture fluid and by incorporation of ferulic esters into their cell walls. s-adenosyl-l-methionine:trans-caffeoyl-coa 3-o-methyltransferase activity, specifically involved in the formation of ferulic esters, is induced under these conditions. such an inducible methyltransferase activity has been found in plant cells of various species. the methyltran ...199116667940
kinetic characterization of caffeoyl-coenzyme a-specific 3-o-methyltransferase from elicited parsley cell suspensions.the activity of caffeoyl-coenzyme a (coa) 3-o-methyltransferase, an enzyme widely distributed in plants and involved in cell wall reinforcement in a disease resistance response, appears to be subject to a complex type of regulation in vivo. in cultured parsley (petroselinum crispum) cells treated with an elicitor from phytophthora megasperma f.sp. glycinea, the enzyme activity is rapidly induced by a transient increase in the rate of de novo transcription. parsley caffeoyl-coa-specific methyltra ...199116668176
single-strand-conformation polymorphism of ribosomal dna for rapid species differentiation in genus phytophthora.single-strand-conformation polymorphism (sscp) of ribosomal dna of 29 species (282 isolates) of phytophthora was characterized in this study. phytophthora boehmeriae, phytophthora botryosa, phytophthora cactorum, phytophthora cambivora, phytophthora capsici, phytophthora cinnamomi, phytophthora colocasiae, phytophthora fragariae, phytophthora heveae, phytophthora hibernalis, phytophthora ilicis, phytophthora infestans, phytophthora katsurae, phytophthora lateralis, phytophthora meadii, phytophth ...200312892637
specific formation of arachidonic acid and eicosapentaenoic acid by a front-end delta5-desaturase from phytophthora megasperma.the biosynthesis of arachidonic acid (20:4(delta5z,8z,11z,14z)) from linoleic acid in plants by transgenic means requires the sequential and specific action of two desaturation reactions and one elongation reaction. here, we describe the isolation of a specific acyl-lipid-desaturase catalyzing the formation of the double bond at position 5 from a cdna library from phytophthora megasperma. the isolated full-length cdna harbors a sequence of 1740 bp encoding a protein of 477 amino acids with a cal ...200515629687
light and fungal elicitor induce 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase mrna in suspension cultured cells of parsley (petroselinum crispum l.).light and fungal elicitor induce mrna encoding 3-deoxy-d-arabino-heptulosonate 7-phosphate (dahp) synthase in suspension cultured cells of parsley (petroselinum crispum l.). the kinetics and dose response of mrna accumulation were similar for dahp synthase and phenylalanine ammonia-lyase (pal). six micrograms of elicitor from phytophthora megasperma f. glycinia gave a detectable induction within 1 hour. induction of dahp synthase and pal mrnas by light was transient, reaching maximal levels at 4 ...199216668708
glycopeptide elicitors of stress responses in tomato cells: n-linked glycans are essential for activity but act as suppressors of the same activity when released from the glycopeptides.induction of ethylene, an early symptom of the stress response in tomato (lycopersicon esculentum [l.] mill) cells, was used as a bioassay to purify elicitor activity from yeast extract. the purified elicitor preparation consisted of small glycopeptides (mean relative molecular weight of approximately 2500) and induced ethylene biosynthesis and phenylalanine ammonia-lyase activity half-maximally at 15 nanograms per milliliter. elicitor activity was partially abolished by pronase and almost compl ...199216668782
elicitation of diterpene biosynthesis in rice (oryza sativa l.) by chitin.cell-free extracts of uv-irradiated rice (oryza sativa l.) leaves have a much greater capacity for the synthesis from geranylgeranyl pyrophosphate of diterpene hydrocarbons, including the putative precursors of rice phytoalexins, than extracts of unstressed leaves (ka wickham, ca west [1992] arch biochem biophys 293: 320-332). an elicitor bioassay was developed on the basis of these observations in which 6-day-old rice cell suspension cultures were incubated for 40 hours with the substance to be ...199216668985
specific elicitors of plant phytoalexin production: detenninants of race specificity in pathogens?race 1 cultures of the phytopathogenic fungus phytophthora megasperma var. sojae produced a specific elicitor of the soybean phytoalexin hydroxyphaseollin that resulted in higher production of the phytoalexin on disease-resistant harosoy 63 soybeans than in the near-isogenic susceptible cultivar harosoy. race 3 of the fungus, which gives susceptible reactions on both soybean cultivars, did not produce the race i specific elicitor.197517844213
ultrastructural and cytochemical aspects of the interaction between the mycoparasite pythium oligandrum and soilborne plant pathogens.abstract the interaction between the oomycete pythium oligandrum and various soilborne oomycete and fungal plant pathogens (p. ultimum, p. aphanidermatum, fusarium oxysporum f. sp. radicis-lycopersici, verticillium albo-atrum, rhizoctonia solani, and phytophthora megasperma) was studied by light and electron microscopy in order to assess the relative contribution of mycoparasitism and antibiosis in the antagonistic process. scanning electron microscope investigations of the interaction regions s ...199918944723
release of a soluble phytoalexin elicitor from mycelial walls of phytophthora megasperma var. sojae by soybean tissues.a soluble elicitor of glyceollin accumulation was released from insoluble mycelial walls of phytophthora megasperma var. sojae after incubation with soybean cotyledon tissue for as little as 2 minutes. various enzymic and chemical treatments of the released elicitor indicated that the activity resided in a carbohydrate moiety, and gel filtration disclosed the presence of at least two active molecular species. cell-free extracts from soybean cotyledons or hypocotyls also released soluble elicitor ...198116661777
host-pathogen interactions : xvii. hydrolysis of biologically active fungal glucans by enzymes isolated from soybean cells.the ability of beta-glucosylase i, a soybean cell wall beta-glucosyl hydrolase, to degrade elicitors of phytoalexin accumulation was studied. extensive beta-glucosylase i treatment of the glucan elicitor isolated from the mycelial walls of phytophthora megasperma var. sojae results in hydrolysis of 77% of the glucosidic bonds of the elicitor and destruction of 94% of its activity. soybean cell walls contain some additional factor, probably one or more additional enzymes, which can assist beta-gl ...198116661873
the structure and function of a soybean beta-glucan-elicitor-binding protein.beta-glucan elicitor (ge), released from the cell wall of the phytopathogenic fungus phytophthora megasperma by soybean glucanases, causes defense reactions in soybean. a ge-binding protein (gebp) was purified from the membrane fraction of soybean root cells, and its cdna was isolated. expression of the cdna clone in tobacco suspension cultured cells and in escherichia coli conferred ge-binding activity to both. an antibody against the recombinant protein was found to inhibit the ge binding with ...19979023377
host-pathogen interactions : xviii. isolation and biological activity of glycinol, a pterocarpan phytoalexin synthesized by soybeans.a previously unrecognized phytoalexin has been isolated from soybean cotyledons that had been infected with bacteria or exposed to ultraviolet light. the phytoalexin has been purified to homogeneity by silica gel flash chromatography and high pressure liquid chromatography. it has been structurally characterized by its ultraviolet, circular dichroism and nuclear magnetic resonance spectra, polarimetry, and its mass spectrometric fragmentation pattern. the phytoalexin, (6as,11as)-3,6a,9-trihydrox ...198116661917
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