The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Bart P H J Thomma - One of the best experts on this subject based on the ideXlab platform.
-
rhamnose synthase activity is required for pathogenicity of the Vascular Wilt fungus verticillium dahliae
Molecular Plant Pathology, 2017Co-Authors: Parthasarathy Santhanam, J C Boshoven, Omar Salas, Kyle Bowler, Tohidul Islam, Mojtaba Keykha Saber, Grardy C M Van Den Berg, Maor Barpeled, Bart P H J ThommaAbstract:The initial interaction of a pathogenic fungus with its host is complex and involves numerous metabolic pathways and regulatory proteins. Considerable attention has been devoted to proteins that play a crucial role in these interactions, with an emphasis on so-called effector molecules that are secreted by the invading microbe to establish the symbiosis. However, the contribution of other types of molecules, such as glycans, is less well appreciated. Here, we present a random genetic screen that enabled us to identify 58 novel candidate genes that are involved in the pathogenic potential of the fungal pathogen Verticillium dahliae, which causes Vascular Wilt diseases in over 200 dicotyledonous plant species, including economically important crops. One of the candidate genes that was identified concerns a putative biosynthetic gene involved in nucleotide sugar precursor formation, as it encodes a putative nucleotide-rhamnose synthase/epimerase-reductase (NRS/ER). This enzyme has homology to bacterial enzymes involved in the biosynthesis of the nucleotide sugar deoxy-thymidine diphosphate (dTDP)-rhamnose, a precursor of L-rhamnose, which has been shown to be required for virulence in several human pathogenic bacteria. Rhamnose is known to be a minor cell wall glycan in fungi and has therefore not been suspected as a crucial molecule in fungal-host interactions. Nevertheless, our study shows that deletion of the VdNRS/ER gene from the V. dahliae genome results in complete loss of pathogenicity on tomato and Nicotiana benthamiana plants, whereas vegetative growth and sporulation are not affected. We demonstrate that VdNRS/ER is a functional enzyme in the biosynthesis of uridine diphosphate (UDP)-rhamnose, and further analysis has revealed that VdNRS/ER deletion strains are impaired in the colonization of tomato roots. Collectively, our results demonstrate that rhamnose, although only a minor cell wall component, is essential for the pathogenicity of V. dahliae.
-
broad taxonomic characterization of verticillium Wilt resistance genes reveals an ancient origin of the tomato ve1 immune receptor
Molecular Plant Pathology, 2017Co-Authors: Yin Song, Zhao Zhang, Michael F Seidl, Aljaz Majer, Jernej Jakse, Branka Javornik, Bart P H J ThommaAbstract:Plant-pathogenic microbes secrete effector molecules to establish themselves on their hosts, whereas plants use immune receptors to try and intercept such effectors in order to prevent pathogen colonization. The tomato cell surface-localized receptor Ve1 confers race-specific resistance against race 1 strains of the soil-borne Vascular Wilt fungus Verticillium dahliae which secrete the Ave1 effector. Here, we describe the cloning and characterization of Ve1 homologues from tobacco (Nicotiana glutinosa), potato (Solanum tuberosum), wild eggplant (Solanum torvum) and hop (Humulus lupulus), and demonstrate that particular Ve1 homologues govern resistance against V. dahliae race 1 strains through the recognition of the Ave1 effector. Phylogenetic analysis shows that Ve1 homologues are widely distributed in land plants. Thus, our study suggests an ancient origin of the Ve1 immune receptor in the plant kingdom.
-
The Brassicaceae-specific EWR1 gene provides resistance to Vascular Wilt pathogens
PLoS ONE, 2014Co-Authors: Koste A Yadeta, Dirk-jan Valkenburg, Mathieu Hanemian, Yves Marco, Bart P H J ThommaAbstract:Soil-borne Vascular Wilt diseases caused by Verticillium spp. are among the most destructive diseases worldwide in a wide range of plant species. The most effective means of controlling Verticillium Wilt diseases is the use of genetic resistance. We have previously reported the identification of four activation-tagged Arabidopsis mutants which showed enhanced resistance to Verticillium Wilt. Among these, one mutant also showed enhanced resistance to Ralstonia solanacearum, a bacterial Vascular Wilt pathogen. Cloning of the activation tag revealed an insertion upstream of gene At3g13437, which we designated as EWR1 (for Enhancer of Vascular Wilt Resistance 1) that encodes a putatively secreted protein of unknown function. The search for homologs of Arabidopsis EWR1 (AtEWR1) in public databases only identified homologs within the Brassicaceae family. We subsequently cloned the EWR1 homolog from Brassica oleracea (BoEWR1) and show that over-expression in Arabidopsis results in V. dahliae resistance. Moreover, over-expression of AtEWR1 and BoEWR1 in N. benthamiana, a member of the Solanaceae family, results in V. dahliae resistance, suggesting that EWR1 homologs can be used to engineer Verticillium Wilt resistance in non-Brassicaceae crops as well.
-
the xylem as battleground for plant hosts and Vascular Wilt pathogens
Frontiers in Plant Science, 2013Co-Authors: Koste A Yadeta, Bart P H J ThommaAbstract:Vascular Wilts are among the most destructive plant diseases that occur in annual crops as well as in woody perennials. These diseases are generally caused by soil-borne bacteria, fungi, and oomycetes that infect through the roots and enter the water-conducting xylem vessels where they proliferate and obstruct the transportation of water and minerals. As a consequence, leaves Wilt and die, which may lead to impairment of the whole plant and eventually to death of the plant. Cultural, chemical, and biological measures to control this group of plant pathogens are generally ineffective, and the most effective control strategy is the use of genetic resistance. Owing to the fact that Vascular Wilt pathogens live deep in the interior of their host plants, studies into the biology of Vascular pathogens are complicated. However, to design novel strategies to combat Vascular Wilt diseases, understanding the (molecular) biology of Vascular pathogens and the molecular mechanisms underlying plant defense against these pathogens is crucial. In this review, we discuss the current knowledge on interactions of Vascular Wilt pathogens with their host plants, with emphasis on host defense responses against this group of pathogens.
-
comparative genomics yields insights into niche adaptation of plant Vascular Wilt pathogens
PLOS Pathogens, 2011Co-Authors: Steven J Klosterman, Bart P H J Thomma, Krishna V Subbarao, Seogchan Kang, Paola Veronese, Scott E Gold, Zehua Chen, Bernard Henrissat, Jongsun Park, Maria D GarciapedrajasAbstract:The Vascular Wilt fungi Verticillium dahliae and V. albo-atrum infect over 200 plant species, causing billions of dollars in annual crop losses. The characteristic Wilt symptoms are a result of colonization and proliferation of the pathogens in the xylem vessels, which undergo fluctuations in osmolarity. To gain insights into the mechanisms that confer the organisms' pathogenicity and enable them to proliferate in the unique ecological niche of the plant Vascular system, we sequenced the genomes of V. dahliae and V. albo-atrum and compared them to each other, and to the genome of Fusarium oxysporum, another fungal Wilt pathogen. Our analyses identified a set of proteins that are shared among all three Wilt pathogens, and present in few other fungal species. One of these is a homolog of a bacterial glucosyltransferase that synthesizes virulence-related osmoregulated periplasmic glucans in bacteria. Pathogenicity tests of the corresponding V. dahliae glucosyltransferase gene deletion mutants indicate that the gene is required for full virulence in the Australian tobacco species Nicotiana benthamiana. Compared to other fungi, the two sequenced Verticillium genomes encode more pectin-degrading enzymes and other carbohydrate-active enzymes, suggesting an extraordinary capacity to degrade plant pectin barricades. The high level of synteny between the two Verticillium assemblies highlighted four flexible genomic islands in V. dahliae that are enriched for transposable elements, and contain duplicated genes and genes that are important in signaling/transcriptional regulation and iron/lipid metabolism. Coupled with an enhanced capacity to degrade plant materials, these genomic islands may contribute to the expanded genetic diversity and virulence of V. dahliae, the primary causal agent of Verticillium Wilts. Significantly, our study reveals insights into the genetic mechanisms of niche adaptation of fungal Wilt pathogens, advances our understanding of the evolution and development of their pathogenesis, and sheds light on potential avenues for the development of novel disease management strategies to combat destructive Wilt diseases.
Isabel M G Roncero - One of the best experts on this subject based on the ideXlab platform.
-
fusarium oxysporum exploring the molecular arsenal of a Vascular Wilt fungus
Molecular Plant Pathology, 2003Co-Authors: Antonio Di Pietro, Marta P Madrid, Zaira Caracuel, Jesus Delgadojarana, Isabel M G RonceroAbstract:SUMMARY Taxonomy: Vascular Wilt fungus; Ascomycete although sexual stage is yet to be found. The most closely related teleomorphic group, Gibberella, is classified within the Pyrenomycetes. Host range: Very broad at the species level. More than 120 different formae speciales have been identified based on specificity to host species belonging to a wide range of plant families. Disease symptoms: Initial symptoms of Vascular Wilt include vein clearing and leaf epinasty, followed by stunting, yellowing of the lower leafs, progressive Wilting of leaves and stem, defoliation and finally death of the plant. In cross-sections of the stem, a brown ring is evident in the area of the Vascular bundles. Some formae speciales are not primarily Vascular pathogens but cause foot- and rootrot or bulbrot. Economic importance: Causes severe losses on most vegetables and flowers, several field crops such as cotton and tobacco, plantation crops such as banana, plantain, coffee and sugarcane, and a few shade trees. Control: Use of resistant varieties is the only practical measure for controlling the disease in the field. Under greenhouse conditions, soil sterilization can be performed. Alternative control methods with potential for the future include soil solarization and biological control with antagonistic bacteria or fungi. Useful websites: http://www.fgsc.net/fus.htm, http://www-genome.wi.mit.edu/annotation/fungi/fusarium/, http://www.cbs.knaw.nl/fusarium/database.html
-
class v chitin synthase determines pathogenesis in the Vascular Wilt fungus fusarium oxysporum and mediates resistance to plant defence compounds
Molecular Microbiology, 2002Co-Authors: Martan P Madrid, Antonio Di Pietro, Isabel M G RonceroAbstract:Summary Chitin, a β-1,4-linked polysaccharide of N-acetylglucosamine, is a major structural component of fungal cell walls. Fungi have multiple classes of chitin synthases that catalyse N-acetylglucosamine polymerization. Here, we demonstrate the requirement for a class V chitin synthase during host infection by the Vascular Wilt pathogen Fusarium oxysporum. The chsV gene was identified in an insertional mutagenesis screen for pathogenicity mutants. ChsV has a putative myosin motor and a chitin synthase domain characteristic of class V chitin synthases. The chsV insertional mutant and a gene replacement mutant of F. oxysporum display morphological abnormalities such as hyphal swellings that are indicative of alterations in cell wall structure and can be partially restored by osmotic stabilizer. The mutants are unable to infect and colonize tomato plants or to grow invasively on tomato fruit tissue. They are also hypersensitive to plant antimicrobial defence compounds such as the tomato phytoanticipin α-tomatine or H2O2. Reintroduction of a functional chsV copy into the mutant restored the growth phenotype of the wild-type strain. These data suggest that F. oxysporum requires a specific class V chitin synthase for pathogenesis, most probably to protect itself against plant defence mechanisms.
-
molecular characterization of a novel endo β 1 4 xylanase gene from the Vascular Wilt fungus fusarium oxysporum
Current Genetics, 2001Co-Authors: E Gomezgomez, Antonio Di Pietro, Isabel M G Roncero, Concepcion HeraAbstract:A gene, xyl5, was identified from the tomato Vascular Wilt fungus Fusarium oxysporum f.sp. lycopersici, whose predicted amino acid sequence shows significant homology with family 11 xylanases. Expression of xyl5 was detected during growth both on xylan and cellulose substrates as carbon sources and on tomato Vascular tissue. RT-PCR analysis revealed the presence of two different transcript sizes, resulting from differential splicing of the third intron. The 3′-untranslated region of the xyl5 transcript contained a region of homology to cellulose-binding domains, suggesting that such a domain may have been part of an ancestral XYL5 version. As shown by RT-PCR, xyl5 is expressed by F. oxysporum exclusively during the initial stages of infection in tomato roots. Targeted inactivation of xyl5 had no detectable effect on virulence.
-
molecular characterization of a subtilase from the Vascular Wilt fungus fusarium oxysporum
Molecular Plant-microbe Interactions, 2001Co-Authors: Antonio Di Pietro, Dolores M Huertasgonzalez, Felix J Gutierrezcorona, Guadalupe Martinezcadena, Emese Meglecz, Isabel M G RonceroAbstract:The gene prt1 was isolated from the tomato Vascular Wilt fungus Fusarium oxysporum f. sp. lycopersici, whose predicted amino acid sequence shows significant homology with subtilisin-like fungal proteinases. Prt1 is a single-copy gene, and its structure is highly conserved among different formae speciales of F. oxysporum. Prt1 is expressed constitutively at low levels during growth on different carbon and nitrogen sources and strongly induced in medium containing collagen and glucose. As shown by reverse transcription-polymerase chain reaction and fluorescence microscopy of F. oxysporum strains carrying a prt1-promoter-green fluorescent protein fusion, prt1 is expressed at low levels during the entire cycle of infection on tomato plants. F. oxysporum strains transformed with an expression vector containing the prt1 coding region fused to the inducible endopolygalacturonase pg1 gene promoter and grown under promoter-inducing conditions secreted high levels of extracellular subtilase activity that resolved i...
-
a map kinase of the Vascular Wilt fungus fusarium oxysporum is essential for root penetration and pathogenesis
Molecular Microbiology, 2001Co-Authors: Antonio Di Pietro, Emese Meglecz, Fe I Garciamaceira, Isabel M G RonceroAbstract:Summary The soil-borne Vascular Wilt fungus Fusarium oxysporum infects a wide variety of plant species by directly penetrating roots, invading the cortex and colonizing the Vascular tissue. We have identified fmk1, encoding a mitogen-activated protein kinase (MAPK) of F. oxysporum that belongs to the yeast and fungal extracellular signal-regulated kinase (YERK1) subfamily. Targeted mutants of F. oxysporum f. sp. lycopersici carrying an inactivated copy of fmk1 have lost pathogenicity on tomato plants but show normal vegetative growth and conidiation in culture. Colonies of the fmk1 mutants are easily wettable, and hyphae are impaired in breaching the liquid‐air interface, suggesting defects in surface hydrophobicity. Fmk1 mutants also show reduced invasive growth on tomato fruit tissue and drastically reduced transcript levels of pl1 encoding the cell wall-degrading enzyme pectate lyase. Conidia of the mutants germinating in the tomato rhizosphere fail to differentiate penetration hyphae, resulting in greatly impaired root attachment. The orthologous MAPK gene Pmk1 from the rice leaf pathogen Magnaporthe grisea complements invasive growth and partially restores surface hydrophobicity, root attachment and pathogenicity in an fmk1 mutant. These results demonstrate that FMK1 controls several key steps in the pathogenesis of F. oxysporum and suggest a fundamentally conserved role for the corresponding MAPK pathway in soil-borne and foliar plant pathogens.
Katherine F Dobinson - One of the best experts on this subject based on the ideXlab platform.
-
characterization of the glyoxalase i gene from the Vascular Wilt fungus verticillium dahliae
Canadian Journal of Microbiology, 2006Co-Authors: A Klimes, Melody Neumann, S J Grant, Katherine F DobinsonAbstract:A glyoxalase I gene homologue (VdGLO1) was identified in the Vascular Wilt fungus Verticillium dahliae by sequence tag analysis of genes expressed during resting structure development. The results of the current study show that the gene encodes a putative 345 amino acid protein with high similarity to glyoxalase I, which produces S-D-lactoylglutathione from the toxic metabolic by-product methylglyoxal (MG). Disruption of the V. dahliae gene by Agrobacterium tumefaciens-mediated transformation resulted in enhanced sensitivity to MG. Mycelial growth of disruption mutants was severely reduced in the presence of 5 mmol/L MG. In contrast, spore production in liquid medium was abolished at 1 mmol/L MG, although not at physiologically relevant concentrations of ≤100 µmol/L. In this first report on the characterization of a glyoxalase I gene in a Vascular Wilt pathogen, we found that disruption of VdGLO1 had no discernable effect on the pathogenicity of V. dahliae. These data suggest that while the glyoxalase sys...
-
sequence tag analysis of gene expression during pathogenic growth and microsclerotia development in the Vascular Wilt pathogen verticillium dahliae
Fungal Genetics and Biology, 2003Co-Authors: Melody Neumann, Katherine F DobinsonAbstract:Two cDNA libraries were constructed from cultures of the Vascular Wilt fungus Verticillium dahliae, grown either in simulated xylem fluid medium (SXM) or under conditions that induce near-synchronous development of microsclerotia. Expressed sequence tags (ESTs) were obtained for over 1000 clones from each library. Most sequences in the two EST collections were unique; nearly 55% of the translated ESTs had strong similarity to protein sequences in the NCBI nonredundant database. ESTs corresponding to melanin biosynthetic enzymes were exclusive to the developing microsclerotia (DMS) collection, and sequences corresponding to extracellular hydrolases (plant cell wall degrading enzymes) were more abundant in that collection. ESTs corresponding to proteins involved in transport and cell growth were more abundant in the SXM collection. The results of this preliminary analysis suggest that the in vitro growth conditions used here provide useful model systems that will facilitate studies of pathogenesis and microsclerotia development in V. dahliae.
-
genetic transformation of the Vascular Wilt fungus verticillium dahliae
Botany, 1995Co-Authors: Katherine F DobinsonAbstract:To facilitate genetic analysis of pathogenicity of Verticillium dahliae, a Vascular Wilt pathogen, a DNA-mediated transformation system has been developed. Resistance to hygromycin B was obtained by transforming spheroplasts with the cosmid vector pAN7-2. Transformation efficiencies ranged between 3 and 5 transformants/μg vector DNA. The transforming DNA was integrated into the V. dahliae genome, in single and multiple copies and in tandem array. In several multicopy transformants, minor alterations in the integrated DNA sequences were evident following extensive vegetative growth in the absence of hygromycin B. Electrophoretic karyotype analysis also provided direct evidence of chromosome rearrangements in two transformants. The availability of a transformation system for V. dahliae will facilitate the cloning and characterization of genes that are important for pathogenicity and development. Key words: Verticillium Wilt, fungal transformation, electrophoretic karyotype, hygromycin B resistance, chromoso...
M I G Roncero - One of the best experts on this subject based on the ideXlab platform.
-
role in pathogenesis of two endo β 1 4 xylanase genes from the Vascular Wilt fungus fusarium oxysporum
Fungal Genetics and Biology, 2002Co-Authors: E Gomezgomez, A. Di Pietro, M C Ruizroldan, M I G Roncero, Concepcion HeraAbstract:A gene, xyl4, whose predicted amino acid sequence shows significant homology with family 11 xylanases, was identified from the tomato Vascular Wilt fungus Fusarium oxysporum f. sp. lycopersici. Expression of xyl4 is induced on oat spelt xylan as the carbon source, subject to carbon catabolite repression and preferentially expressed at alkaline ambient pH. Transcript levels of xyl4 on an inducing carbon source are differentially regulated by the nature and concentration of the nitrogen source. As shown by RT-PCR, xyl4 is expressed by F. oxysporum during the entire cycle of infection on tomato plants. Targeted inactivation of xyl4 and of xyl3, a previously identified gene of F. oxysporum f. sp. lycopersici encoding a family 10 xylanase, had no detectable effect on virulence on tomato plants, demonstrating that both genes are not essential for pathogenicity.
-
two xylanase genes of the Vascular Wilt pathogen fusarium oxysporum are differentially expressed during infection of tomato plants
Molecular Genetics and Genomics, 1999Co-Authors: M C Ruizroldan, A. Di Pietro, M D Huertasgonzalez, M I G RonceroAbstract:Two genes encoding putative family F xylanases from the tomato Vascular Wilt pathogen Fusarium oxysporum f.sp. lycopersici have been cloned and sequenced. The two genes, designated xyl2 and xyl3, encode proteins with calculated molecular masses of 33 and 39.3 kDa and isoelectric points of 8.9 and 6.7, respectively. The predicted amino acid sequences show significant homology to other family F xylanases. XYL3 contains a cellulose-binding domain in its N-terminal region. Southern analysis suggested that xyl2 and xyl3 homologs are also present in other formae speciales of F. oxysporum. Both genes were expressed during growth on oat spelt xylan and tomato Vascular tissue in vitro. RT-PCR revealed that xyl3 is expressed in roots and in the lower stems of tomato plants infected by F. oxysporum f.sp. lycopersici throughout the whole disease cycle, whereas xyl2 is only expressed during the final stages of disease.
-
cloning expression and role in pathogenicity of pg1 encoding the major extracellular endopolygalacturonase of the Vascular Wilt pathogen fusarium oxysporum
Molecular Plant-microbe Interactions, 1998Co-Authors: A. Di Pietro, M I G RonceroAbstract:pg1 encoding the major in vitro extracellular endopolygalacturonase of the tomato Vascular Wilt pathogen Fusarium oxysporum f. sp. lycopersici was cloned and sequenced. The deduced mature protein had a calculated molecular mass of 35.5 kDa and a pI of 6.2, and showed significant similarity with other fungal endoPGs. pg1 mRNA was induced in vitro by citrus pectin, tomato Vascular tissue, 0.1% D-galacturonic acid, and polygalacturonic acid, and repressed by 1% D-galacturonic acid and 1% glucose. Reverse transcription-polymerase chain reaction revealed pg1 expression in roots and lower stems of tomato plants infected by F. oxysporum f. sp. lycopersici. Three naturally occurring F. oxysporum f. sp. melonis isolates deficient in PG1 were transformed with the cloned gene. The PG1 enzyme secreted by the transformants had the same molecular mass, pI, and glycosylation pattern as those of the donor isolate. Polygalacturonase activity in cultures of transformants grown in vitro on citrus pectin and on melon plants,...
Antonio Di Pietro - One of the best experts on this subject based on the ideXlab platform.
-
fusaric acid contributes to virulence of fusarium oxysporum on plant and mammalian hosts
Molecular Plant Pathology, 2018Co-Authors: Cristina Lopezdiaz, Antonio Di Pietro, Vahid Rahjoo, Michael Sulyok, Veronica Ghionna, Adela Martinvicente, Javier Capilla, Manuel S LopezbergesAbstract:Fusaric acid (FA) is amongst the oldest identified secondary metabolites produced by Fusarium species, known for a long time to display strong phytotoxicity and moderate toxicity to animal cells; however, the cellular targets of FA and its function in fungal pathogenicity remain unknown. Here, we investigated the role of FA in Fusarium oxysporum, a soil-borne cross-kingdom pathogen that causes Vascular Wilt on more than 100 plant species and opportunistic infections in humans. Targeted deletion of fub1, encoding a predicted orthologue of the polyketide synthase involved in FA biosynthesis in F. verticillioides and F. fujikuroi, abolished the production of FA and its derivatives in F. oxysporum. We further showed that the expression of fub1 was positively controlled by the master regulator of secondary metabolism LaeA and the alkaline pH regulator PacC through the modulation of chromatin accessibility at the fub1 locus. FA exhibited strong phytotoxicity on tomato plants, which was rescued by the exogenous supply of copper, iron or zinc, suggesting a possible function of FA as a chelating agent of these metal ions. Importantly, the severity of Vascular Wilt symptoms on tomato plants and the mortality of immunosuppressed mice were significantly reduced in fub1Δ mutants and fully restored in the complemented strains. Collectively, these results provide new insights into the regulation and mode of action of FA, as well as on the function of this phytotoxin during the infection process of F. oxysporum.
-
fusarium oxysporum exploring the molecular arsenal of a Vascular Wilt fungus
Molecular Plant Pathology, 2003Co-Authors: Antonio Di Pietro, Marta P Madrid, Zaira Caracuel, Jesus Delgadojarana, Isabel M G RonceroAbstract:SUMMARY Taxonomy: Vascular Wilt fungus; Ascomycete although sexual stage is yet to be found. The most closely related teleomorphic group, Gibberella, is classified within the Pyrenomycetes. Host range: Very broad at the species level. More than 120 different formae speciales have been identified based on specificity to host species belonging to a wide range of plant families. Disease symptoms: Initial symptoms of Vascular Wilt include vein clearing and leaf epinasty, followed by stunting, yellowing of the lower leafs, progressive Wilting of leaves and stem, defoliation and finally death of the plant. In cross-sections of the stem, a brown ring is evident in the area of the Vascular bundles. Some formae speciales are not primarily Vascular pathogens but cause foot- and rootrot or bulbrot. Economic importance: Causes severe losses on most vegetables and flowers, several field crops such as cotton and tobacco, plantation crops such as banana, plantain, coffee and sugarcane, and a few shade trees. Control: Use of resistant varieties is the only practical measure for controlling the disease in the field. Under greenhouse conditions, soil sterilization can be performed. Alternative control methods with potential for the future include soil solarization and biological control with antagonistic bacteria or fungi. Useful websites: http://www.fgsc.net/fus.htm, http://www-genome.wi.mit.edu/annotation/fungi/fusarium/, http://www.cbs.knaw.nl/fusarium/database.html
-
class v chitin synthase determines pathogenesis in the Vascular Wilt fungus fusarium oxysporum and mediates resistance to plant defence compounds
Molecular Microbiology, 2002Co-Authors: Martan P Madrid, Antonio Di Pietro, Isabel M G RonceroAbstract:Summary Chitin, a β-1,4-linked polysaccharide of N-acetylglucosamine, is a major structural component of fungal cell walls. Fungi have multiple classes of chitin synthases that catalyse N-acetylglucosamine polymerization. Here, we demonstrate the requirement for a class V chitin synthase during host infection by the Vascular Wilt pathogen Fusarium oxysporum. The chsV gene was identified in an insertional mutagenesis screen for pathogenicity mutants. ChsV has a putative myosin motor and a chitin synthase domain characteristic of class V chitin synthases. The chsV insertional mutant and a gene replacement mutant of F. oxysporum display morphological abnormalities such as hyphal swellings that are indicative of alterations in cell wall structure and can be partially restored by osmotic stabilizer. The mutants are unable to infect and colonize tomato plants or to grow invasively on tomato fruit tissue. They are also hypersensitive to plant antimicrobial defence compounds such as the tomato phytoanticipin α-tomatine or H2O2. Reintroduction of a functional chsV copy into the mutant restored the growth phenotype of the wild-type strain. These data suggest that F. oxysporum requires a specific class V chitin synthase for pathogenesis, most probably to protect itself against plant defence mechanisms.
-
molecular characterization of a novel endo β 1 4 xylanase gene from the Vascular Wilt fungus fusarium oxysporum
Current Genetics, 2001Co-Authors: E Gomezgomez, Antonio Di Pietro, Isabel M G Roncero, Concepcion HeraAbstract:A gene, xyl5, was identified from the tomato Vascular Wilt fungus Fusarium oxysporum f.sp. lycopersici, whose predicted amino acid sequence shows significant homology with family 11 xylanases. Expression of xyl5 was detected during growth both on xylan and cellulose substrates as carbon sources and on tomato Vascular tissue. RT-PCR analysis revealed the presence of two different transcript sizes, resulting from differential splicing of the third intron. The 3′-untranslated region of the xyl5 transcript contained a region of homology to cellulose-binding domains, suggesting that such a domain may have been part of an ancestral XYL5 version. As shown by RT-PCR, xyl5 is expressed by F. oxysporum exclusively during the initial stages of infection in tomato roots. Targeted inactivation of xyl5 had no detectable effect on virulence.
-
molecular characterization of a subtilase from the Vascular Wilt fungus fusarium oxysporum
Molecular Plant-microbe Interactions, 2001Co-Authors: Antonio Di Pietro, Dolores M Huertasgonzalez, Felix J Gutierrezcorona, Guadalupe Martinezcadena, Emese Meglecz, Isabel M G RonceroAbstract:The gene prt1 was isolated from the tomato Vascular Wilt fungus Fusarium oxysporum f. sp. lycopersici, whose predicted amino acid sequence shows significant homology with subtilisin-like fungal proteinases. Prt1 is a single-copy gene, and its structure is highly conserved among different formae speciales of F. oxysporum. Prt1 is expressed constitutively at low levels during growth on different carbon and nitrogen sources and strongly induced in medium containing collagen and glucose. As shown by reverse transcription-polymerase chain reaction and fluorescence microscopy of F. oxysporum strains carrying a prt1-promoter-green fluorescent protein fusion, prt1 is expressed at low levels during the entire cycle of infection on tomato plants. F. oxysporum strains transformed with an expression vector containing the prt1 coding region fused to the inducible endopolygalacturonase pg1 gene promoter and grown under promoter-inducing conditions secreted high levels of extracellular subtilase activity that resolved i...