| triticone a: a novel bioactive lactam with potential as a molecular probe. | triticone a is one member of a family of novel compounds which are spirocyclic lactams produced by several plant pathogenic fungi including drechslera tritici repentis on wheat. it undergoes racemization to form triticone b and when tested, the enantiomeric mixture causes chlorosis and necrosis on a wide range of plants. fluorescein diacetate treated protoplasts in conjunction with various triticone treatments allowed for accurate quantitation of the biological activity of the toxin. various phy ... | 1988 | 3196330 |
| purification and immunological characterization of toxic components from cultures of pyrenophora tritici-repentis. | to facilitate the genetic analysis of pathogenicity in the wheat-pyrenophora tritici-repentis interaction, a host-selective toxic protein, designated toxa, was purified from culture filtrates of this fungus. toxa was shown to be a 13.2-kda heat-stable protein which induced visible necrosis in sensitive wheat cultivars at an average minimum concentration of 60 nm. polyclonal antibodies raised against toxa were shown by western analysis and indirect immunoprecipitation to be specific for this prot ... | 1995 | 7772802 |
| a single gene encodes a selective toxin causal to the development of tan spot of wheat. | the identification and characterization of pathogenicity factors are essential to an understanding of the molecular events that regulate the interaction of plant-pathogenic microbes with their hosts. we have isolated the gene that encodes a host-selective toxic protein produced by the fungus pyrenophora tritici-repentis and confirmed that this gene functions in the plant as the primary determinant of pathogenicity in the pyrenophora-wheat interaction. these results demonstrate that a single gene ... | 1997 | 9061946 |
| heterologous expression of functional ptr toxa. | ptr toxa, a proteinaceous host-selective toxin (hst) produced by the fungus pyrenophora tritici-repentis, was expressed in escherichia coli and purified as a polyhistidine-tagged, fusion protein (nc-fp). nc-fp, consisting of both the n and c domains of the toxa open reading frame (orf), is produced as an insoluble protein in e. coli at approximately 10 to 16 mg per liter of culture. following in vitro refolding, nc-fp elicits cultivar-specific necrosis in wheat, with a specific activity similar ... | 2000 | 10755309 |
| characterization of the toxb gene from pyrenophora tritici-repentis. | the toxb gene was cloned and characterized from a race 5 isolate of pyrenophora tritici-repentis from north dakota. toxb contains a 261-bp open reading frame that encodes a 23 amino acid putative signal peptide and a 64 amino acid host-selective toxin, ptr toxb. analysis of ptr toxb from heterologous expression in pichia pastoris confirms that toxb encodes a host-selective toxin. | 2001 | 11332732 |
| the effect of plant height on tan spot on durum wheat in southern saskatchewan. | tan spot [caused by pyrenophora tritici-repentis (died.) drechs.] is the most important leaf disease of durum wheat (triticum turgidum l. var. durum). most of the durum cultivars in western canada are of conventional height but development of shorter cultivars is desirable. changes in microenvironment resulting from a height reduction might cause greater leaf spot development. the effect of plant height on tan spot of durum wheat was determined in five pairs of genotypes near-isogenic for plant ... | 2002 | 11756267 |
| chromosome-based molecular characterization of pathogenic and non-pathogenic wheat isolates of pyrenophora tritici-repentis. | the toxa gene of pyrenophora tritici-repentis encodes a host-selective toxin (ptr toxa) that has been shown to confer pathogenicity when used to transform a non-pathogenic wheat isolate. major karyotype polymorphisms between pathogenic and non-pathogenic strains, and to a lesser extent among pathogenic strains, and among non-pathogenic strains were identified. toxa was localized to a 3.0 mb chromosome. pcr-based subtraction was carried out with the toxa chromosome as tester dna and genomic dna f ... | 2002 | 12409102 |
| role of the arginyl-glycyl-aspartic motif in the action of ptr toxa produced by pyrenophora tritici-repentis. | a fundamental problem of plant science is to understand the biochemical basis of plant/pathogen interactions. the foliar disease tan spot of wheat (triticum aestivum), caused by pyrenophora tritici-repentis, involves ptr toxa, a proteinaceous host-selective toxin that causes host cell death. the fungal gene toxa encodes a 17.2-kd pre-pro-protein that is processed to produce the mature 13.2-kd toxin. amino acids 140 to 142 of the pre-pro-protein form an arginyl-glycyl-aspartic (rgd) sequence, a m ... | 2002 | 12428019 |
| inoculum sources of the tan spot fungus pyrenophora tritici-repentis in the netherlands. | since 1994 the importance of tan spot of wheat has increased in the wheat growing areas of the netherlands. the purpose of the present study was to determine inoculum sources of this disease caused by pyrenophora tritici-repentis. both in 1999 and 2000, the incidence of tan spot was assessed in 40 commercial fields of winter wheat scattered over the main wheat growing areas of the netherlands. adjoining fields were checked for presence of stubble or crops with straw covers and the surrounding ve ... | 2002 | 12701430 |
| characterization of the multiple-copy host-selective toxin gene, toxb, in pathogenic and nonpathogenic isolates of pyrenophora tritici-repentis. | toxb, a gene that encodes a 6.6-kda host-selective toxin (hst), is present in several races of the wheat pathogen pyrenophora tritici-repentis. to learn more about the multiple toxb open reading frames (orfs), six of the estimated nine copies from a race 5 isolate were cloned and analyzed. all six copies of toxb have identical 261-bp orfs and thus encode the same form of ptr toxb. sequence analysis of regions flanking the cloned toxb loci revealed that the majority of loci are associated with po ... | 2004 | 15141950 |
| ptr toxa requires multiple motifs for complete activity. | ptr toxa was the first proteinaceous necrosis-inducing toxin identified and cloned from the wheat pathogen, pyrenophora tritici-repentis. how this protein causes necrosis in sensitive wheat cultivars is not known. in an effort to understand the structural features of ptr toxa required for induction of necrosis, we employed a combination of site-directed mutagenesis and peptide inhibition studies. mutagenesis was carried out on conserved motifs within the active domain of ptr toxa. proteins with ... | 2004 | 15141953 |
| the ipm wheat model--results of a three-year study in north rhine-westphalia, lower saxony and schleswig-holstein. | under the primary utilisation of phytosanitary production factors such as selection of variety, crop rotation and n fertilisation according to plant requirements, the ipm wheat model comprises the elements diagnosis (qualitative = type of pathogen, quantitative = disease severity), scientifically grounded treatment thresholds which, as critical values in pathogen development, can be applied to define the optimum time of fungicide application, and pathogen-specific effective fungicides and applic ... | 2003 | 15151283 |
| molecular mapping of resistance to pyrenophora tritici-repentis race 5 and sensitivity to ptr toxb in wheat. | tan spot, caused by pyrenophora tritici-repentis (ptr), is an economically important foliar disease in the major wheat growing areas of the world. multiple races of the pathogen have been characterized based on their ability to cause necrosis and/or chlorosis in differential wheat lines. isolates of race 5 cause chlorosis only, and they produce a host-selective toxin designated ptr toxb that induces chlorosis when infiltrated into sensitive genotypes. the international triticeae mapping initiati ... | 2004 | 15292990 |
| 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 |
| competition, facilitation, and niche differentiation in two foliar pathogens. | we studied competition between the obligate biotroph puccinia triticina (designated here as puccinia) and the facultative saprophyte pyrenophora tritici-repentis (designated here as pyrenophora) in older and younger leaves in a set of three host genotypes selected to be resistant to puccinia only, pyrenophora only, or neither. age-related resistance is important for both of these pathogens. the facultative saprophyte pyrenophora was generally a stronger competitor than the biotrophic puccinia, e ... | 2005 | 15711822 |
| identification of quantitative trait loci for race-nonspecific resistance to tan spot in wheat. | tan spot, caused by pyrenophora tritici-repentis (ptr), is an economically important foliar disease in the major wheat growing areas throughout the world. multiple races of the pathogen have been characterized based on their ability to cause necrosis and/or chlorosis on differential wheat lines. in this research, we evaluated a population of recombinant inbred lines derived from a cross between the common wheat varieties grandin and br34 for reaction to tan spot caused by ptr races 1-3 and 5. co ... | 2005 | 15895202 |
| inhibition of efflux transporter-mediated fungicide resistance in pyrenophora tritici-repentis by a derivative of 4'-hydroxyflavone and enhancement of fungicide activity. | populations of the causal agent of wheat tan spot, pyrenophora tritici-repentis, that are collected from fields frequently treated with reduced fungicide concentrations have reduced sensitivity to strobilurin fungicides and azole fungicides (c14-demethylase inhibitors). energy-dependent efflux transporter activity can be induced under field conditions and after in vitro application of sublethal amounts of fungicides. efflux transporters can mediate cross-resistance to a number of fungicides that ... | 2005 | 15933029 |
| localization of ptr toxa produced by pyrenophora tritici-repentis reveals protein import into wheat mesophyll cells. | the plant pathogenic fungus pyrenophora tritici-repentis secretes host-selective toxins (hsts) that function as pathogenicity factors. unlike most hsts that are products of enzymatic pathways, at least two toxins produced by p. tritici-repentis are proteins and, thus, products of single genes. sensitivity to these toxins in the host is conferred by a single gene for each toxin. to study the site of action of ptr toxa (toxa), toxin-sensitive and -insensitive wheat (triticum aestivum) cultivars we ... | 2005 | 16199615 |
| structure of ptr toxa: an rgd-containing host-selective toxin from pyrenophora tritici-repentis. | tan spot of wheat (triticum aestivum), caused by the fungus pyrenophora tritici-repentis, has significant agricultural and economic impact. ptr toxa (toxa), the first discovered proteinaceous host-selective toxin, is produced by certain p. tritici-repentis races and is necessary and sufficient to cause cell death in sensitive wheat cultivars. we present here the high-resolution crystal structure of toxa in two different crystal forms, providing four independent views of the protein. toxa adopts ... | 2005 | 16214901 |
| macro- and microcolinearity between the genomic region of wheat chromosome 5b containing the tsn1 gene and the rice genome. | the tsn1 gene in wheat confers sensitivity to a proteinaceous host-selective toxin (ptr toxa) produced by the tan spot fungus (pyrenophora tritici-repentis) and lies within a gene-rich region of chromosome 5b. to use the rice genome sequence information for the map-based cloning of tsn1, colinearity between the wheat genomic region containing tsn1 and the rice genome was determined at the macro- and microlevels. macrocolinearity was determined by testing 28 expressed sequence markers (esms) span ... | 2006 | 16372189 |
| genomic analysis and marker development for the tsn1 locus in wheat using bin-mapped ests and flanking bac contigs. | the wheat tsn1 gene confers sensitivity to the host-selective toxin ptr toxa produced by the tan spot fungus (pyrenophora tritici-repentis). the long-term goal of this research is to isolate tsn1 using a positional cloning approach. here, we evaluated 54 ests (expressed sequence tags) physically mapped to deletion bin 5bl 0.75-0.76, which is a gene-rich region containing tsn1. twenty-three est loci were mapped as either pcr-based single-stranded conformational polymorphism or rflp markers in a l ... | 2006 | 16456656 |
| development of toxa and toxb promoter-driven fluorescent protein expression vectors for use in filamentous ascomycetes. | the green fluorescent protein (gfp) has been established as the premier in vivo reporter for investigations of gene expression, protein localization, and cell and organism dynamics. the fungal transformation vector pct74, with sgfp under the control of the toxa promoter from pyrenophora tritici-repentis, effectively expresses gfp in a diverse group of filamentous ascomycetes. due to the versatility of toxa promoter-driven expression of gfp, we constructed an additional set of fluorescent protein ... | 2005 | 16596965 |
| in-house sulfur sad phasing: a case study of the effects of data quality and resolution cutoffs. | single-wavelength anomalous diffraction (sad) utilizing the weak signal of inherently present s atoms can be successfully used to solve macromolecular structures, although this is mostly performed with data from a synchrotron rather than a laboratory source. using high redundancy, sufficiently accurate anomalous data may now often be collected in the laboratory using cu kalpha x-ray radiation. systematic analyses of a laboratory-derived data set illuminate the effects of data quality, redundancy ... | 2006 | 16790926 |
| the tsn1-toxa interaction in the wheat-stagonospora nodorum pathosystem parallels that of the wheat-tan spot system. | the wheat tan spot fungus (pyrenophora tritici-repentis) produces a well-characterized host-selective toxin (hst) known as ptr toxa, which induces necrosis in genotypes that harbor the tsn1 gene on chromosome 5b. in previous work, we showed that the stagonospora nodorum isolate sn2000 produces at least 2 hsts (sntox1 and sntoxa). sensitivity to sntox1 is governed by the snn1 gene on chromosome 1b in wheat. sntoxa is encoded by a gene with a high degree of similarity to the ptr toxa gene. here, w ... | 2006 | 17213908 |
| molecular mapping of resistance genes to tan spot [pyrenophora tritici-repentis race 1] in synthetic wheat lines. | synthetic wheat lines (2n = 6x = 42, aabbdd), which are amphiploids developed from the hybrid between tetraploid wheat (triticum turgidum l., 2n = 4x = 28, aabb) and aegilops tauschii coss. (2n = 2x = 14, dd), are important sources of resistance against tan spot of wheat caused by pyrenophora tritici-repentis. in the present study, inheritance, allelism and genetic linkage analysis in synthetic wheat lines have been carried out. segregation analysis of the phenotypic and molecular data in f(2:3) ... | 2007 | 17219206 |
| ptr toxa interacts with a chloroplast-localized protein. | pyrenophora tritici-repentis, causal agent of tan spot of wheat, produces host-selective toxins that are determinants of pathogenicity or virulence. ptr toxa (toxa), a proteinaceous toxin produced by p. tritici-repentis, is a necrotizing toxin produced by the most common races isolated from infected wheat. recent studies have shown that toxa is internalized into the mesophyll cells and localizes to chloroplasts of sensitive wheat cultivars only. we employed a yeast two-hybrid screen in an effort ... | 2007 | 17313168 |
| the stagonospora nodorum-wheat pathosystem involves multiple proteinaceous host-selective toxins and corresponding host sensitivity genes that interact in an inverse gene-for-gene manner. | we recently showed that the wheat pathogen stagonospora nodorum produces proteinaceous host-selective toxins (hsts). these toxins include sntox1 as well as sntoxa, a hst first identified from pyrenophora tritici-repentis that was implicated in a very recent horizontal gene transfer event from s. nodorum to p. tritici-repentis. compelling evidence implicating sntoxa and sntox1 in disease development has been obtained. here, we report the partial purification and characterization of a third hst de ... | 2007 | 17573802 |
| homologs of toxb, a host-selective toxin gene from pyrenophora tritici-repentis, are present in the genome of sister-species pyrenophora bromi and other members of the ascomycota. | pyrenophora tritici-repentis requires the production of host-selective toxins (hsts) to cause the disease tan spot of wheat, including ptr toxa, ptr toxb, and ptr toxc. pyrenophora bromi, the species most closely related to p. tritici-repentis, is the causal agent of brown leaf spot of bromegrass. because of the relatedness of p. bromi and p. tritici-repentis, we investigated the possibility that p. bromi contains sequences homologous to toxa and/or toxb, the products of which may be involved in ... | 2008 | 18226934 |
| host-specific toxins: effectors of necrotrophic pathogenicity. | host-specific toxins (hsts) are defined as pathogen effectors that induce toxicity and promote disease only in the host species and only in genotypes of that host expressing a specific and often dominant susceptibility gene. they are a feature of a small but well-studied group of fungal plant pathogens. classical hst pathogens include species of cochliobolus, alternaria and pyrenophora. recent studies have shown that stagonospora nodorum produces at least four separate hsts that interact with fo ... | 2008 | 18384660 |
| a gene for resistance to a necrosis-inducing isolate of pyrenophora tritici-repentis located on 5bl of triticum aestivum cv. chinese spring. | several sources of high-level resistance to tan spot caused by pyrenophora tritici-repentis have been identified in hexaploid wheat (triticum aestivum l.). this study was conducted to determine the number and chromosome location of a gene(s) in the cultivar chinese spring (cs) that confers resistance to a tan necrosis inducing isolate (nec+chl−) of p. tritici-repentis, 86-124, and insensitivity to ptr necrosis toxin. reciprocal crosses were made between cs (resistant-insensitive) and 'keny ... | 1996 | 18469918 |
| identification of novel tan spot resistance loci beyond the known host-selective toxin insensitivity genes in wheat. | tan spot, caused by pyrenophora tritici-repentis, is a destructive foliar disease of wheat causing significant yield reduction in major wheat growing areas throughout the world. the objective of this study was to identify quantitative trait loci (qtl) conferring resistance to tan spot in the synthetic hexaploid wheat (shw) line ta4152-60. a doubled haploid (dh) mapping population derived from ta4152-60 x nd495 was inoculated with conidia produced by isolates of each of four virulent races of p. ... | 2008 | 18575834 |
| identification of a chlorosis-inducing toxin from pyrenophora tritici-repentis and the chromosomal location of an insensitivity locus in wheat. | abstract culture filtrate from pyrenophora tritici-repentis race 1 isolate 78-62 contained a genotype-specific toxin which elicited extensive chlorosis on sensitive wheat genotypes. this toxin was partially purified using gel filtration, ion exchange, and reversed-phase chromatography. the chlorosis toxin was found to be a polar, nonionic, low-molecular-weight molecule. wheat genotypes infiltrated with crude culture filtrate and partially purified chlorosis toxin exhibited the same chlorotic sym ... | 2002 | 18943027 |
| cultivar mixtures for the simultaneous management of multiple diseases: tan spot and leaf rust of wheat. | abstract because of differences in life histories between puccinia triticina, a highly specialized, polycyclic, windborne pathogen with a shallow dispersal gradient, and pyrenophora tritici-repentis, a residue-borne pathogen with a steep dispersal gradient, wheat mixtures are expected to be more effective at controlling leaf rust than tan spot. the objectives of this research were to determine the effect of two-cultivar mixtures with varying proportions and different pathogen resistance profiles ... | 2004 | 18943072 |
| epidemiology of foliar blights (spot blotch and tan spot) of wheat in the plains bordering the himalayas. | abstract helminthosporium leaf blight (hlb), a complex of spot blotch caused by cochliobolus sativus and of tan spot caused by pyrenophora tritici-repentis, is a major wheat disease in south asia. this 2-year study elucidated hlb development and its impact on yield. symptoms caused by c. sativus and p. tritici-repentis were first observed at the seedling and tillering stages, respectively. the number of airborne conidia and leaves infected by the two pathogens remained low for several weeks unde ... | 2005 | 18943117 |
| emergence of tan spot disease caused by toxigenic pyrenophora tritici-repentis in australia is not associated with increased deployment of toxin-sensitive cultivars. | the wheat disease tan (or yellow leaf) spot, caused by pyrenophora tritici-repentis, was first described in the period 1934 to 1941 in canada, india, and the united states. it was first noted in australia in 1953 and only became a serious disease in the 1970s. the emergence of this disease has recently been linked to the acquisition by p. tritici-repentis of the toxa gene from the wheat leaf and glume blotch pathogen, stagonospora nodorum. toxa encodes a host-specific toxin that interacts with t ... | 2008 | 18943215 |
| population genetic analysis of a global collection of pyrenophora tritici-repentis, causal agent of tan spot of wheat. | abstract the work presented here is the first major study to analyze the genetic diversity within the worldwide population of the economically important wheat pathogen pyrenophora tritici-repentis. the genetic structure of field populations of p. tritici-repentis was determined using amplified fragment length polymorphism markers along with sequence data from the internal transcribed spacer region of the ribosomal dna. ninetyseven fungal isolates were collected from naturally infected wheat and ... | 2005 | 18943466 |
| a combination of phenotypic and genotypic characterization strengthens pyrenophora tritici-repentis race identification. | abstract pyrenophora tritici-repentis, causal agent of tan spot of wheat, produces multiple host-selective toxins (hsts), including ptr toxa, ptr toxb, and ptr toxc. the specific complement of hsts produced by a particular isolate determines its host cultivar specificity. each unique specificity profile, represented by the differential induction of necrosis or chlorosis on a standard set of wheat differentials, defines a unique race. eight races of p. tritici-repentis have been formally publishe ... | 2007 | 18943600 |
| distribution and pathogenic characterization of pyrenophora tritici-repentis and stagonospora nodorum in ohio. | abstract to determine the distribution of stagonospora nodorum and pyrenophora tritici-repentis on wheat in ohio, flag leaves with lesions were collected from wheat-producing counties in 2002 and 2003. counties were arbitrarily grouped into seven regions. log-linear analysis of pathogen presence within regions indicated that the presence of s. nodorum was independent of the presence of p. tritici-repentis. a logistic analysis revealed that the occurrence of both pathogens varied by region in one ... | 2006 | 18943668 |
| identification and molecular mapping of a gene conferring resistance to pyrenophora tritici-repentis race 3 in tetraploid wheat. | abstract race 3 of the fungus pyrenophora tritici-repentis, causal agent of tan spot, induces differential symptoms in tetraploid and hexaploid wheat, causing necrosis and chlorosis, respectively. this study was conducted to examine the genetic control of resistance to necrosis induced by p. tritici-repentis race 3 and to map resistance genes identified in tetraploid wheat (triticum turgidum). a mapping population of recombinant inbred lines (rils) was developed from a cross between the resistan ... | 2006 | 18943754 |
| restriction fragment length polymorphism mapping of resistance to two races of pyrenophora tritici-repentis in adult and seedling wheat. | abstract resistance to the chlorosis factor of tan spot of wheat, caused by the ascomycete pyrenophora tritici-repentis, has been reported to be quantitative and a single quantitative trait loci (qtl), qtsc.ndsu-1a, explained 35% of the variation for resistance to a single isolate in seedlings of recombinant inbred (ri) lines derived from the cross w-7984/opata 85. the objectives of this study were to determine the number and locations of genes conditioning resistance to the same isolate in adul ... | 2001 | 18943946 |
| forensic pathology of canadian bread wheat: the case of tan spot. | abstract pyrenophora tritici-repentis causes necrosis and chlorosis in its wheat host. susceptibility to races 2 (necrosis) and 5 (chlorosis) of the pathogen is known to be mediated by ptr toxa and ptr toxb, respectively. sensitivity to each toxin is controlled by a single dominant and independently inherited gene. we used sensitivity to ptr toxa and ptr toxb as two genetic markers to investigate the origin and the state of tan spot susceptibility in canadian western red spring (cwrs) wheat over ... | 2005 | 18943983 |
| genetic control of resistance to tan necrosis induced by pyrenophora tritici-repentis, races 1 and 2, in spring and winter wheat genotypes. | abstract the symptoms of tan spot of wheat, caused by pyrenophora triticirepentis, include a tan necrosis component and an extensive chlorosis component. since tan spot has become the major component of the leafspotting disease complex of wheat in western canada, the need for resistant cultivars has increased. this study was conducted to determine whether the resistance to tan spot found in a diverse set of spring and winter wheat genotypes was due to resistance genes not previously reported. th ... | 2005 | 18943987 |
| reaction of ptr toxa-insensitive wheat mutants to pyrenophora tritici-repentis race 1. | abstract the host-selective toxin ptr toxa is produced by races 1 and 2 of pyrenophora tritici-repentis, causal agent of tan spot of wheat. ptr toxa has been causally associated with pathogenicity by the race 2 phenotype in this system. however, the role of toxin in disease caused by race 1, the most prevalent form of the fungus in the central and northern great plains of north america, has not been rigorously investigated. three independent wheat lines harboring mutations for insensitivity to p ... | 2002 | 18944137 |
| genetic analysis of resistance to pyrenophora tritici-repentis races 1 and 5 in tetraploid and hexaploid wheat. | tan spot of wheat, caused by the fungus pyrenophora tritici-repentis, is a destructive disease worldwide that can lead to serious losses in quality and quantity of wheat grain production. resistance to multiple races of p. tritici-repentis was identified in a wide range of genetically diverse genotypes, including three different species triticum aestivum (aabbdd), t. spelta (aabbdd), and t. turgidum (aabb). the major objectives of this study were to determine the genetic control of resistance to ... | 2008 | 18944295 |
| the identification of two new races of pyrenophora tritici-repentis from the host center of diversity confirms a one-to-one relationship in tan spot of wheat. | abstract pyrenophora tritici-repentis, causal agent of tan spot, induces necrosis and chlorosis in its wheat host. the tan spot system conforms to the toxin model and three host-specific toxins have been identified (ptr toxa, ptr toxb, and putative ptr toxc). processing of a collection of isolates, obtained in the fertile crescent and caucasus regions, yielded two new virulence patterns. isolate az35-5 combined the virulences of races 2 and 5 and was classified in the new race 7. isolates ts93-7 ... | 2003 | 18944352 |
| role of host sensitivity to ptr toxa in development of tan spot of wheat. | abstract pyrenophora tritici-repentis race 2 produces ptr toxa, a host-selective toxin previously described as a pathogenicity factor for tan spot on wheat. the objective of this research was to evaluate the role of host sensitivity to toxin, conditioned by a single dominant gene on chromosome 5bl, in the disease development by race 2. an f(2)-derived f(6) recombinant inbred population of 108 wheat lines, produced from crosses of toxin-sensitive, disease-susceptible cv. kulm with the toxin-insen ... | 2003 | 18944353 |
| advances in the characterization of the pyrenophora tritici-repentis-wheat interaction. | abstract tan spot of wheat, caused by the fungus pyrenophora tritici-repentis, is a destructive disease found in wheat-growing regions worldwide that can lead to serious yield losses. changes in cultural practices have led to an increase in the severity and incidence of tan spot. following infection, compatible races of the fungus elicit two distinct symptoms in differential wheat lines: tan necrosis and (extensive) chlorosis. tan necrosis has been clearly demonstrated by several groups to resul ... | 1999 | 18944714 |
| genetic analysis of sensitivity to a pyrenophora tritici-repentis necrosis-inducing toxin in durum and common wheat. | abstract the fungus pyrenophora tritici-repentis produces a toxin (ptr toxa) that causes rapid cell necrosis in sensitive wheat genotypes. a single recessive gene (tsn1) on chromosome 5bl in common wheat confers insensitivity to this toxin. our objectives were to analyze the allelic relationships of genotypes that have shown insensitivity to a p. tritici-repentis necrosis-inducing toxin, map the gene for insensitivity to the necrosis-inducing factor produced by p. tritici-repentis in a durum whe ... | 1999 | 18944773 |
| structural and physical properties of a necrosis-inducing toxin from pyrenophora tritici-repentis. | abstract cultivar-specific toxic metabolites of pyrenophora tritici-repentis are involved in the appearance of necrotic and chlorotic foliar lesions characteristic of tan spot. a p. tritici-repentis necrosis-inducing toxin, ptr necrosis toxin, was purified from isolate 86-124, sequenced by gas-phase amino acid microsequencing, and characterized by circular dichroism (cd) spectroscopy and isoelectric focusing. the purified protein had a similar amino acid composition and molecular weight as previ ... | 1997 | 18945135 |
| neural networks that distinguish infection periods of wheat tan spot in an outdoor environment. | abstract tan spot of wheat, caused by pyrenophora tritici-repentis, provided a model system for testing disease forecasts based on an artificial neural network. infection periods for p. tritici-repentis on susceptible wheat cultivars were identified from a bioassay system that correlated tan spot incidence with crop growth stage and 24-h summaries of environmental data, including temperature, relative humidity, wind speed, wind direction, solar radiation, precipitation, and flat-plate resistance ... | 1997 | 18945158 |
| a proteomic evaluation of pyrenophora tritici-repentis, causal agent of tan spot of wheat, reveals major differences between virulent and avirulent isolates. | pyrenophora tritici-repentis causes tan spot, an important foliar disease of wheat. the fungus produces multiple host-specific toxins, including ptr toxb, a chlorosis-inducing protein encoded by the toxb gene. a homolog of toxb is also found in avirulent isolates of the fungus. in order to improve understanding of the role of this homolog and evaluate the general pathogenic ability of p. tritici-repentis, we compared the proteomes of avirulent race 4 and virulent race 5 isolates of the pathogen. ... | 2009 | 19206107 |
| genome characterization of pyrenophora tritici-repentis isolates reveals high plasticity and independent chromosomal location of toxa and toxb. | the fungus pyrenophora tritici-repentis (died.) causes tan spot, an important leaf disease of wheat worldwide. isolates of this pathogen have been collected and characterized into eight races on the basis of their ability to produce three different host-selective toxins. the karyotype of 47 isolates was determined by pulsed field gel electrophoresis. the collection originated from different parts of the world and included genotypes from all races. a single isolate was characterized for each of r ... | 2009 | 19236569 |
| influence of water activity and temperature on growth and mycotoxin production by isolates of pyrenophora tritici-repentis from wheat. | pyrenophora tritici-repentis is a phytopathogenic fungus that can infect wheat kernels and leaves, causing red smudge and tan spot, respectively. a number of p. tritici-repentis isolates have been shown to be mycotoxigenic, producing the anthraquinone mycotoxins emodin, catenarin and islandicin. the influence of water activity (a(w); 0.75-0.99 a(w)) and temperature (5-45 degrees c) on growth and mycotoxin production by five isolates of p. tritici-repentis was studied. all isolates grew at 0.95-0 ... | 2009 | 19268381 |
| rflp mapping of resistance to chlorosis induction by pyrenophora tritici-repentis in wheat. | tan spot, caused by pyrenophora tritici-repentis, is an economically important disease in major wheat production areas. the fungus can produce two genetically distinct symptoms on leaves of susceptible wheat genotypes: tan necrosis (nec) and extensive chlorosis (ch1). our objectives were to determine the number of genes conditioning resistance to tan spot in a population of wheat recombinant inbred lines, and map the chromosomal location of the resistance genes using rflps. conidia produced by t ... | 1997 | 19352751 |
| a host-selective toxin of pyrenophora tritici-repentis, ptr toxa, induces photosystem changes and reactive oxygen species accumulation in sensitive wheat. | ptr toxa (toxa) is a proteinaceous necrotizing host-selective toxin produced by pyrenophora tritici-repentis, a fungal pathogen of wheat (triticum aestivum). in this study, we have found that treatment of toxa-sensitive wheat leaves with toxa leads to a light-dependent accumulation of reactive oxygen species (ros) that correlates with the onset of necrosis. furthermore, the accumulation of ros and necrosis could be inhibited by the antioxidant n-acetyl cysteine, providing further evidence that r ... | 2009 | 19445591 |
| biosynthesis and role in virulence of the histone deacetylase inhibitor depudecin from alternaria brassicicola. | depudecin, an eleven-carbon linear polyketide made by the pathogenic fungus alternaria brassicicola, is an inhibitor of histone deacetylase (hdac). a chemically unrelated hdac inhibitor, hc toxin, was earlier shown to be a major virulence factor in the interaction between cochliobolus carbonum and its host, maize. in order to test whether depudecin is also a virulence factor for a. brassicicola, we identified the genes for depudecin biosynthesis and created depudecin-minus mutants. the depudecin ... | 2009 | 19737099 |
| analysis of transcriptome changes induced by ptr toxa in wheat provides insights into the mechanisms of plant susceptibility. | to obtain greater insight into the molecular events underlying plant disease susceptibility, we studied transcriptome changes induced by a host-selective toxin of pyrenophora tritici-repentis, ptr toxa (toxa), on its host plant, wheat. transcriptional profiling of toxa-treated leaves of a toxa-sensitive wheat cultivar was performed using the genechip wheat genome array. an improved and up-to-date annotation of the wheat microarray was generated and a new tool for array data analysis (brat) was d ... | 2009 | 19825681 |
| quantitative trait loci for resistance to pyrenophora tritici-repentis race 1 in a chinese wheat. | tan spot, caused by pyrenophora tritici-repentis, is an economically important foliar disease of wheat worldwide. eight races of the pathogen have been characterized on the basis of their ability to cause necrosis or chlorosis in a set of differential wheat lines. race 1 produces two host-selective toxins, ptr toxa and ptr toxc, that induce necrosis and chlorosis, respectively, on leaves of sensitive wheat genotypes. a population of recombinant inbred lines was developed from a cross between chi ... | 2010 | 20373968 |
| genetic diversity of the mating type and toxin production genes in pyrenophora tritici-repentis. | pyrenophora tritici-repentis, the causal agent of tan spot on wheat, is a homothallic loculoascomycete with a complex race structure. the objectives of this study were to confirm the homothallic nature of the pathogen, characterize mating type diversity and toxin production genes in a global collection of strains, and analyze how these traits are associated between each other and with existing races. the pseudothecia production capacity, race identification, mating type locus (mat), internal tra ... | 2010 | 20373969 |
| geographical variation and positive diversifying selection in the host-specific toxin sntoxa. | summary the host-specific toxin toxa produced by the wheat pathogens pyrenophora tritici-repentis and phaeosphaeria nodorum interacts with the product of the dominant plant gene tsn1 to induce necrosis. the toxa gene is thought to have been acquired by py. tritici-repentis from ph. nodorum through a recent horizontal gene transfer event. pcr and sequence analysis indicate that the level of toxa variation, including gene deletion, in ph. nodorum (sntoxa) is significantly higher than in py. tritic ... | 2007 | 20507502 |
| inhibition of photosynthesis and modification of the wheat leaf proteome by ptr toxb: a host-specific toxin from the fungal pathogen pyrenophora tritici-repentis. | tan spot, caused by pyrenophora tritici-repentis, is an important foliar disease of wheat. the fungus produces the host-specific, chlorosis-inducing toxin ptr toxb. to better understand toxin action, we examined the effects of ptr toxb on sensitive wheat. photosynthesis, as measured by infrared gas analysis, declined significantly within 12 h of toxin treatment, prior to the development of chlorosis at 48-72 h. analysis by 2-de revealed a total of 102 protein spots with significantly altered int ... | 2010 | 20540119 |
| host-selective toxins, ptr toxa and ptr toxb, as necrotrophic effectors in the pyrenophora tritici-repentis-wheat interaction. | host-selective toxins (hsts) are effectors produced by some necrotrophic pathogenic fungi that typically confer the ability to cause disease. often, diseases caused by pathogens that produce hsts follow an inverse gene-for-gene model where toxin production is required for the ability to cause disease and a single locus in the host is responsible for toxin sensitivity and disease susceptibility. pyrenophora tritici-repentis represents an ideal pathogen for studying the biological significance of ... | 2010 | 20646221 |
| chromosomal location and molecular mapping of a tan spot resistance gene in the winter wheat cultivar red chief. | the winter wheat cultivar red chief has been identified as the wheat cultivar most resistant to pyrenophora tritici-repentis (ptr). this study was undertaken to determine the inheritance, chromosomal location and molecular mapping of a tan spot resistance gene in red chief. χ² analysis of the f2 segregation data of the hybrids between 21 monosomic lines of the susceptible wheat cultivar chinese spring and the resistant cultivar red chief revealed that tan spot resistance in cv. red chief is cont ... | 2010 | 20720298 |
| identification and validation of quantitative trait loci conferring tan spot resistance in the bread wheat variety ernie. | tan spot, caused by pyrenophora tritici-repentis, is a foliar disease of wheat, and it can inflict serious reduction in grain yield and quality. the bread wheat variety ernie was found to be immune to this disease in australia, and its genetic control was investigated by quantitative trait loci (qtl) analysis using a doubled haploid population. eight qtl were identified in this population from three independent trials, and four of them were derived from the parent ernie. the most significant qtl ... | 2010 | 20865401 |
| influence of carbon source on growth and mycotoxin production by isolates of pyrenophora tritici-repentis from wheat. | the fungus pyrenophora tritici-repentis can infect wheat kernels, causing red smudge, and has been shown to produce the anthraquinone mycotoxins emodin, catenarin, and islandicin. the growth of 8 fungal isolates from diverse regions was evaluated on various culture media and was found to be generally slowest on the semisynthetic fries medium. the choice of carbon source had a significant effect on mycotoxin production, as assessed by high-performance liquid chromatography. the highest emodin con ... | 2010 | 20962911 |
| new developments in pathogenicity and virulence of necrotrophs. | it was generally considered that necrotrophic plant pathogenic fungi possessed simplistic pathogenic mechanisms being typically reliant on 'blasting' their way through host tissue with a battery of lytic and degradative enzymes. however recent studies have suggested that this is not true and that necrotrophic fungal pathogens can subtly manipulate the host during infection in a manner similar to biotrophic pathogens. for example, it has been demonstrated that the wheat pathogens stagonospora nod ... | 2010 | 20965135 |
| pyrenophora bromi, causal agent of brownspot of bromegrass, expresses a gene encoding a protein with homology and similar activity to ptr toxb, a host-selective toxin of wheat. | ptr toxb, encoded by toxb, is one of multiple host-selective toxins (hst) produced by the wheat pathogen pyrenophora tritici-repentis. homologs of toxb are found in several ascomycetes, including sister species pyrenophora bromi, causal agent of brownspot of bromegrass. due to the close evolutionary relatedness of p. tritici-repentis and p. bromi and that of their grass hosts, we hypothesized that homologs of toxb in p. bromi may act as hst in the disease interaction between p. bromi and bromegr ... | 2011 | 21091157 |
| decorospora, a new genus for the marine ascomycete pleospora gaudefroyi. | in this paper, we investigate the phylogenetic placement of pleospora gaudefroyi using partial ssu as well as its ribosomal dna sequences. both ssu and its data sets agreed in the placement of p. gaudefroyi. parsimony and neighbor-joining analyses of each data set placed p. gaudefroyi within the pleosporaceae with 100% bootstrap support. pleospora gaudefroyi was sister taxon in the pleosporaceae represented by alternaria alternata, cochliobolus sativus, pleospora herbarum, pyrenophora tritici-re ... | 2002 | 21156538 |
| horizontal gene and chromosome transfer in plant pathogenic fungi affecting host range. | plant pathogenic fungi adapt quickly to changing environments including overcoming plant disease resistance genes. this is usually achieved by mutations in single effector genes of the pathogens, enabling them to avoid recognition by the host plant. in addition, horizontal gene transfer (hgt) and horizontal chromosome transfer (hct) provide a means for pathogens to broaden their host range. recently, several reports have appeared in the literature on hgt, hct and hybridization between plant path ... | 2011 | 21223323 |
| identification of novel genomic regions associated with resistance to pyrenophora tritici-repentis races 1 and 5 in spring wheat landraces using association analysis. | tan spot, caused by pyrenophora tritici-repentis, is a major foliar disease of wheat worldwide. host plant resistance is the best strategy to manage this disease. traditionally, bi-parental mapping populations have been used to identify and map quantitative trait loci (qtl) affecting tan spot resistance in wheat. the association mapping (am) could be an alternative approach to identify qtl based on linkage disequilibrium (ld) within a diverse germplasm set. in this study, we assessed resistance ... | 2011 | 21744229 |
| RNA-mediated gene silencing of ToxB in Pyrenophora tritici-repentis. | The fungus Pyrenophora tritici-repentis causes tan spot, a wheat leaf disease of worldwide importance. The pathogen produces three host-selective toxins, including Ptr ToxB, which causes chlorophyll degradation and foliar chlorosis on toxin-sensitive wheat genotypes. The ToxB gene, which codes for Ptr ToxB, was silenced in a wild-type race 5 isolate of the fungus thorough a sense- and antisense-mediated silencing mechanism. Toxin production by the silenced strains was evaluated in culture filtra ... | 2011 | 21980935 |
| quantitative variation in effector activity of toxa isoforms from stagonospora nodorum and pyrenophora tritici-repentis. | toxa is a proteinaceous necrotrophic effector produced by stagonospora nodorum and pyrenophora tritici-repentis. in this study, all eight mature isoforms of the toxa protein were purified and compared. circular dichroism spectra indicated that all isoforms were structurally intact and had indistinguishable secondary structural features. toxa isoforms were infiltrated into wheat lines that carry the sensitivity gene tsn1. it was observed that different wheat lines carrying identical tsn1 alleles ... | 2012 | 22250581 |
| assessing the mycotoxigenic threat of necrotrophic pathogens of wheat. | pathogenic fungi are the causal agents of many significant plant diseases around the world. these diseases often result in significant yield reductions, leading to lower food production rates and economic losses. several of these pathogenic fungi also produce mycotoxins during infection, which are harmful to human and animal health. whilst some of these toxins and the fungi that produce them have been studied intensively, the mycotoxigenic potential of many of these pathogens remains largely unk ... | 2011 | 23605924 |
| tsn1-mediated host responses to toxa from pyrenophora tritici-repentis. | the toxin sensitivity gene tsn1 interacts with ptr toxa (toxa), a host-selective toxin produced by the necrotrophic fungus pyrenophora tritici-repentis. the molecular mechanisms associated with cell death in sensitive wheat cultivars following toxa application are not well understood. to address this question, we used the affymetrix genechip wheat genome array to compare gene expression in a sensitive wheat cultivar possessing the tsn1 gene with the insensitive wheat cv. nec103, which lacks the ... | 2009 | 19656041 |
| [study of the effect of volatile metabolites of trichoderma hamatum on the growth of phytopathogenic soilborne fungi.]. | volatile compounds produced by trichoderma hamatum were tested for their capacity to suppress in vitro the growth of alternaria citri, bipolaris cynodontis, bipolaris sorokiniana, curvularia brachyspora, curvularia lunata, curvularia oryzae-sativae, drechslera tritici-repentis, rhizoctonia solani, sclerotinia minor and sclerotium rolfsii. the organisms were cultured in an apparatus made with two erlenmeyer flasks assembled by their top parts. with the aid of the gas chromatographic technique the ... | 1997 | 17655390 |