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B Mieslerova - One of the best experts on this subject based on the ideXlab platform.

  • first detection of tomato powdery mildew caused by Oidium neolycopersici in south africa
    South African Journal of Botany, 2015
    Co-Authors: Ales Lebeda, B Mieslerova, Levente Kiss, Tunde Jankovics, E J Van Der Linde
    Abstract:

    Oidium neolycopersici has a world-wide distribution causing severe epidemics mainly on greenhouse tomatoes. Currently, only Leveillula taurica has been reported on tomato from South Africa. However, another powdery mildew species on tomato was found recently. Based on morphological comparison and molecular analysis, its identity was confirmed as O. neolycopersici. The possible means of introduction and other aspects of this finding are discussed.

  • reactive oxygen species generation and peroxidase activity during Oidium neolycopersici infection on lycopersicon species
    Plant Physiology and Biochemistry, 2004
    Co-Authors: Kateřina Mlickova, Ales Lebeda, Lenka Luhova, B Mieslerova
    Abstract:

    Abstract Histochemical and biochemical study of plant tissue responses were carried out on three Lycopersicon spp. accessions differing in response to Oidium neolycopersici . High production of superoxide anion was observed mainly in infected leaves of highly susceptible Lycopersicon esculentum cv. ‘Amateur’ during the first hours post inoculation (hpi). The production of hydrogen peroxide as well as an increase of peroxidase (POX) activity were detected mainly in resistant accessions at 4–12 hpi. A signal confirming the presence of very active POX was found in the apical part of tubes of germinating fungus and inside dead conidia. Increased soluble POX and catalase activity in leaf extracts of resistant accessions L. chmielewskii (LA 2663) and L. hirsutum (LA 2128) (20 hpi) correlated with the percentage of dead cells in infection sites. The correlation between production of reactive oxygen species (ROS) and activity of enzymes participating in their metabolism and hypersensitive response was evident during plant defence response.

  • variation in Oidium neolycopersici development on host and non host plant species and their tissue defence responses
    Annals of Applied Biology, 2004
    Co-Authors: B Mieslerova, Ales Lebeda, Roy Kennedy
    Abstract:

    Summary Detailed studies of the infection processes of Oidium neolycopersici (tomato powdery mildew) and plant tissue responses were carried out on 10 Lycopersicon spp. accessions and one of each species of Cucumis sativus, Datura stramonium, Lactuca sativa, Petunia hybrida and Pisum sativum with different levels of resistance. Germination of O. neolycopersici conidia was not inhibited by the host plant. However, in the early stages of O. neolycopersici infection significant differences in conidial germ tube development on resistant and susceptible plant lines were observed. The first substantial differences appeared after 24 h post inoculation (hpi). Mycelia and conidiophores developed on susceptible lines; however, there was no mycelial development on resistant plant lines. The most frequent resistant response in Lycopersicon species was the necrotic (hypersensitive) reaction (HR), occasionally followed by pathogen development. The completely resistant accession L. hirsutum (LA 1347) showed only a limited number of necrotic host cells per infection site (2%). In Oidium resistant tomato lines OR 4061 and OR 960008 the existence of adult resistance was detected. This phenomenon occurred mainly in accession OR 4061. Rapid development and profuse sporulation of O. neolycopersici was observed on juvenile plants (6–8 wk old), however this was in contrast to the slow development and sporadic sporulation observed on 4 month old plants. Evidence of posthaustorial resistance was observed in the interaction of O. neolycopersici with non-host species (Lactuca sativa and Pisum sativum.) This was in contrast to Datura stramonium and Petunia hybrida, where development of powdery mildew was delayed at a later stage in the infection cycle. With the exception of Pisum sativum, the necrotic (hypersensitive) response was observed often.

  • comparative morphological studies on tomato powdery mildew Oidium neolycopersici
    Acta Phytopathologica Et Entomologica Hungarica, 2002
    Co-Authors: B Mieslerova, Ales Lebeda, Roy Kennedy, R Novotny
    Abstract:

    Fourteen isolates of tomato powdery mildew (Oidium neolycopersici) and one isolate of the following species: Podosphaera fusca (= Sphaerotheca fusca), Erysiphe orontii (cucumber powdery mildews), Erysiphe cicho­ra­cearum (lettuce powdery mildew) and Erysiphe aquilegiae var. ranunculi (Ranunculus lingua powdery mildew) were used for com­parative morpho­logical studies. Basic characteristics of the anamorphs, including outer conidial wall patterns, were compared using light and scanning electron microscopy (SEM). In main morphological features, O. neo­lyco­persici was strongly differentiated from E. cichoracearum, E. orontii and P. fusca. However, based on morphological features (e.g. germination type; appres­sorium shape; morphology of conidiophores) O. neolyco­per­sici was close to E. aquilegiae var. ranunculi (both belong to Oidium subgen. Pseudo­idium) and it probably could be placed to Erysiphe sect. Erysiphe (= Erysiphe s. str.)

  • variability in pathogenicity of Oidium neolycopersici on lycopersicon species
    Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz, 2002
    Co-Authors: Ales Lebeda, B Mieslerova
    Abstract:

    The pathogenicity of Oidium neolycopersici (formerly mentioned as O. lycopersici) isolates originating from the Czech Republic, Germany, the Netherlands and England were compared using data (percentage of maximal infection degree (% max ID)) from inoculation experiments on 35 (resp. 60) accessions of wild Lycopersicon species. Considerable variability was revealed within the isolates tested. The English isolate of O. neolycopersici exhibited strongly differentiated pathogenicity. The value of some wild Lycopersicon spp. germplasm (L. hirsutum, L. pennellii) as resistance sources was confirmed. Specific Lycopersicon spp. accessions, which showed reproducible and clear differential (race specific) reaction patterns with specific pathogen isolates, were proposed as a preliminary differential set. Within the O. neolycopersici isolates studied, the existence of three races (OL1, OL2 and OL3) was proposed.

Ales Lebeda - One of the best experts on this subject based on the ideXlab platform.

  • first detection of tomato powdery mildew caused by Oidium neolycopersici in south africa
    South African Journal of Botany, 2015
    Co-Authors: Ales Lebeda, B Mieslerova, Levente Kiss, Tunde Jankovics, E J Van Der Linde
    Abstract:

    Oidium neolycopersici has a world-wide distribution causing severe epidemics mainly on greenhouse tomatoes. Currently, only Leveillula taurica has been reported on tomato from South Africa. However, another powdery mildew species on tomato was found recently. Based on morphological comparison and molecular analysis, its identity was confirmed as O. neolycopersici. The possible means of introduction and other aspects of this finding are discussed.

  • reactive oxygen species generation and peroxidase activity during Oidium neolycopersici infection on lycopersicon species
    Plant Physiology and Biochemistry, 2004
    Co-Authors: Kateřina Mlickova, Ales Lebeda, Lenka Luhova, B Mieslerova
    Abstract:

    Abstract Histochemical and biochemical study of plant tissue responses were carried out on three Lycopersicon spp. accessions differing in response to Oidium neolycopersici . High production of superoxide anion was observed mainly in infected leaves of highly susceptible Lycopersicon esculentum cv. ‘Amateur’ during the first hours post inoculation (hpi). The production of hydrogen peroxide as well as an increase of peroxidase (POX) activity were detected mainly in resistant accessions at 4–12 hpi. A signal confirming the presence of very active POX was found in the apical part of tubes of germinating fungus and inside dead conidia. Increased soluble POX and catalase activity in leaf extracts of resistant accessions L. chmielewskii (LA 2663) and L. hirsutum (LA 2128) (20 hpi) correlated with the percentage of dead cells in infection sites. The correlation between production of reactive oxygen species (ROS) and activity of enzymes participating in their metabolism and hypersensitive response was evident during plant defence response.

  • variation in Oidium neolycopersici development on host and non host plant species and their tissue defence responses
    Annals of Applied Biology, 2004
    Co-Authors: B Mieslerova, Ales Lebeda, Roy Kennedy
    Abstract:

    Summary Detailed studies of the infection processes of Oidium neolycopersici (tomato powdery mildew) and plant tissue responses were carried out on 10 Lycopersicon spp. accessions and one of each species of Cucumis sativus, Datura stramonium, Lactuca sativa, Petunia hybrida and Pisum sativum with different levels of resistance. Germination of O. neolycopersici conidia was not inhibited by the host plant. However, in the early stages of O. neolycopersici infection significant differences in conidial germ tube development on resistant and susceptible plant lines were observed. The first substantial differences appeared after 24 h post inoculation (hpi). Mycelia and conidiophores developed on susceptible lines; however, there was no mycelial development on resistant plant lines. The most frequent resistant response in Lycopersicon species was the necrotic (hypersensitive) reaction (HR), occasionally followed by pathogen development. The completely resistant accession L. hirsutum (LA 1347) showed only a limited number of necrotic host cells per infection site (2%). In Oidium resistant tomato lines OR 4061 and OR 960008 the existence of adult resistance was detected. This phenomenon occurred mainly in accession OR 4061. Rapid development and profuse sporulation of O. neolycopersici was observed on juvenile plants (6–8 wk old), however this was in contrast to the slow development and sporadic sporulation observed on 4 month old plants. Evidence of posthaustorial resistance was observed in the interaction of O. neolycopersici with non-host species (Lactuca sativa and Pisum sativum.) This was in contrast to Datura stramonium and Petunia hybrida, where development of powdery mildew was delayed at a later stage in the infection cycle. With the exception of Pisum sativum, the necrotic (hypersensitive) response was observed often.

  • comparative morphological studies on tomato powdery mildew Oidium neolycopersici
    Acta Phytopathologica Et Entomologica Hungarica, 2002
    Co-Authors: B Mieslerova, Ales Lebeda, Roy Kennedy, R Novotny
    Abstract:

    Fourteen isolates of tomato powdery mildew (Oidium neolycopersici) and one isolate of the following species: Podosphaera fusca (= Sphaerotheca fusca), Erysiphe orontii (cucumber powdery mildews), Erysiphe cicho­ra­cearum (lettuce powdery mildew) and Erysiphe aquilegiae var. ranunculi (Ranunculus lingua powdery mildew) were used for com­parative morpho­logical studies. Basic characteristics of the anamorphs, including outer conidial wall patterns, were compared using light and scanning electron microscopy (SEM). In main morphological features, O. neo­lyco­persici was strongly differentiated from E. cichoracearum, E. orontii and P. fusca. However, based on morphological features (e.g. germination type; appres­sorium shape; morphology of conidiophores) O. neolyco­per­sici was close to E. aquilegiae var. ranunculi (both belong to Oidium subgen. Pseudo­idium) and it probably could be placed to Erysiphe sect. Erysiphe (= Erysiphe s. str.)

  • variability in pathogenicity of Oidium neolycopersici on lycopersicon species
    Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz, 2002
    Co-Authors: Ales Lebeda, B Mieslerova
    Abstract:

    The pathogenicity of Oidium neolycopersici (formerly mentioned as O. lycopersici) isolates originating from the Czech Republic, Germany, the Netherlands and England were compared using data (percentage of maximal infection degree (% max ID)) from inoculation experiments on 35 (resp. 60) accessions of wild Lycopersicon species. Considerable variability was revealed within the isolates tested. The English isolate of O. neolycopersici exhibited strongly differentiated pathogenicity. The value of some wild Lycopersicon spp. germplasm (L. hirsutum, L. pennellii) as resistance sources was confirmed. Specific Lycopersicon spp. accessions, which showed reproducible and clear differential (race specific) reaction patterns with specific pathogen isolates, were proposed as a preliminary differential set. Within the O. neolycopersici isolates studied, the existence of three races (OL1, OL2 and OL3) was proposed.

Susumu Takamatsu - One of the best experts on this subject based on the ideXlab platform.

  • podosphaera lini ascomycota erysiphales revisited and reunited with Oidium lini
    Plant pathology & quarantine online, 2019
    Co-Authors: Uwe Braun, Preston Chris D, Cook R T A, M Gotz, Susumu Takamatsu
    Abstract:

    Podosphaera lini (Erysiphaceae) has recently been detected on linseed, Linum usitatissimum var. crepitans, in England and represents the first unequivocal record of this powdery mildew species from Great Britain. The history of powdery mildew on linseed/flax in the UK is critically discussed. DNA sequence data (ITS + 28S rDNA) have been retrieved, from the British material and a specimen from Germany, to be used for phylogenetic analyses. The position of P. lini as a species of its own in the genus Podosphaera, close to P. macularis (hop powdery mildew), was confirmed in the ITS-based phylogeny. The phylogenetic results, in concordance with the morphological traits of the flax powdery mildew (small peridial cells of the chasmothecia), place this species in Podosphaera sect. Sphaerotheca subsect. Sphaerotheca. Oidium lini, described from Croatia by Skoric in 1926, was later erroneously reduced to a synonymy with Golovinomyces orontii. Oidium lini has been reassessed and is now regarded as a synonym of Podosphaera lini. Oidium lini, cited in the literature as a name published by Bondartsev in 1913, is critically discussed and reviewed. The name O. lini was most likely never validly introduced and is doubtful.

  • molecular characterization of Oidium sp on solanum betaceum in india
    Environment and Ecology, 2013
    Co-Authors: Pankaj Baiswar, Susumu Takamatsu, S V Ngachan, Uwe Braun, Satish Chandra, M Harada
    Abstract:

    Severe symptoms of powdery mildew disease were observed on Solanum betaceum. Mor- phologically, the pathogen was indistinguishable from Oidium neolycopersici. Molecular evidence based on amplification of rDNA ITS region, includ- ing the 5.8S rDNA revealed that the sequence was identical to Oidium sp. on Sedum alboroseum (EU047572), and differs one base from those of O. neolycopersici on tomato and Erysiphe aquilegiae. In cross inoculation tests under polyhouse, this pathogen was unable to infect S. lycopersicum, S. melongena, S. gilow and S. indicum. This is the first attempt to characterize this pathogen using molecu- lar tools.

  • Morphological and molecular characterization of Oidium subgenus ReticulOidium (powdery mildew) newly occurred on cucumber in Japan
    Journal of General Plant Pathology, 2009
    Co-Authors: Keiko Uchida, Susumu Takamatsu, Sanae Matsuda, Kazuhiro So, Yukio Sato
    Abstract:

    In 2002, a powdery mildew with catenate conidia lacking fibrosin bodies was found on cucumber in a greenhouse in Kanagawa Prefecture, Japan. Morphological observation revealed that the fungus belongs to Oidium subgenus ReticulOidium , anamorph of the genus Golovinomyces . Molecular phylogenetic analyses of the nucleotide sequences of the rDNA ITS regions and D1/D2 domains of the 28S rDNA indicated that the fungus belongs to the clade of G. orontii with other Golovinomyces fungi from a wide range of host plants, suggesting that the fungus was newly transported from abroad. Because there has been no prior report of cucumber powdery mildew caused by ReticulOidium , further research on the physiology, epidemiology, control and resistant cucumber varieties is required.

  • powdery mildew on tomato caused by Oidium neolycopersici in changchun china
    Plant Pathology, 2008
    Co-Authors: Susumu Takamatsu, Y Li
    Abstract:

    A powdery mildew was observed on tomato ( Solanum lycopersicum formerly Lycopersicon esculentum ) in greenhouses in Changchun in September 2006. Mildew first appeared as white circular patches on the adaxial leaf surface. As the disease progressed, abaxial leaf surface, stems and petioles were covered by cotton-like masses of mycelia and conidia. Yellow lesions appeared on the abaxial surfaces which turned necrotic and led to defoliation. Young plants (cotyledon period) through to flowering plants were affected, while the fruits remained free from infection. Conidia were ellipsoid or cylindrical, produced singly, lacked distinct fibrosin bodies and measured 22–51 × 13–25 μ m (average 34·2 × 19·1 μ m, n = 150). Conidiophores were unbranched and measured 60–125 μ m (average 83·8 μ m, n = 100). Appressoria were nipple-shaped or slightly lobed. Foot cells were cylindric, sometimes slightly flexuous, followed by 1 or 2 cells and measured 27–53 × 6–10 μ m (average 39·8 × 7·4 μ m, n = 100). Germ tubes were produced from the side of conidia ending in lobed appressoria. Chasmothecia were not observed. The latent period of this disease was 5–7 days. The fungus from tomato also infected tobacco ( Nicotiana tabacum ) by inoculation but the symptoms on tobacco were usually small and localized. The morphological characteristics of the fungus described above fit Oidium neolycopersici (Kiss et al ., 2001). In June 1988, tomato powdery mildew was found in Xinjiang, and the pathogen was identified as Oidiopsis taurica (anamorphic state of Leveillula taurica ; Jia, 1990). Oidium neolycopersici clearly differs from Oidiopsis taurica by its ectophytic nature. In May 1991, Fang et al . (1992) found tomato powdery mildew in Shengyang and identified the pathogen as Erysiphe polygoni based on the anamorphic characteristics. In November 2003, Wang et al . (2004) found tomato powdery mildew in Shengyang and identified the pathogen as Oidiopsis lycopersici . Oidium neolycopersici sometimes forms conidiophores with pseudo-chains in humid conditions, and has been confused with Oidiopsis lycopersici with conidia produced in chains. This is the first report of tomato powdery mildew caused by Oidium neolycopersici in China.

  • Sawadaea nankinensis comb. nov.: a powdery mildew fungus of Acer buergerianum
    Mycoscience, 2008
    Co-Authors: Susumu Takamatsu, Hideo Yamamoto, Uwe Braun
    Abstract:

    The anamorphic state of a powdery mildew on trident maple ( Acer buergerianum , Aceraceae), belonging to Sawadaea , has been observed since 1980 in Tokyo and other areas of Japan. Since the autumn of 2003, this fungus has begun to produce chasmothecia in various areas of Japan, which were consistent with Erysiphe nankinensis (= Uncinula nankinensis ), but apparently contradictory to the characteristics of the anamorph. Based on a molecular phylogenetic analysis using DNA separately extracted from the anamorph and teleomorph of the fungus on A. buergerianum , it could be demonstrated that sequences of this fungus are sister to Sawadaea . As the anamorph belongs to Oidium subgen. OctagOidium and because of the phylogenetic position within the Sawadaea clade, the new combination Sawadaea nankinensis is proposed for this species. The genus Sawadaea is emended to comprise species with consistently unbranched appendages.

Hideyoshi Toyoda - One of the best experts on this subject based on the ideXlab platform.

  • Oidium neolycopersici intraspecific variability inferred from amplified fragment length polymorphism analysis and relationship with closely related powdery mildew fungi infecting various plant species
    Phytopathology, 2008
    Co-Authors: Tunde Jankovics, Marc Bardin, Philippe C Nicot, Yoshinori Matsuda, Hideyoshi Toyoda, R E Niks, Gabor M Kovacs, Levente Kiss
    Abstract:

    Jankovics, T., Bai, Y., Kovacs, G. M., Bardin, M., Nicot, P. C., Toyoda, H., Matsuda, Y., Niks, R. E., and Kiss, L. 2008. Oidium neolycopersici: Intraspecific variability inferred from amplified fragment length polymorphism analysis and relationship with closely related powdery mildew fungi infecting various plant species. Phytopathology 98:529-540. Previous works indicated a considerable variation in the pathogenicity, virulence, and host range of Oidium neolycopersici isolates causing tomato powdery mildew epidemics in many parts of the world. In this study, rDNA internal transcribed spacer (ITS) sequences, and amplified fragment length polymorphism (AFLP) patterns were analyzed in 17 O. neolycopersici samples collected in Europe, North America, and Japan, including those which overcame some of the tomato major resistance genes. The ITS sequences were identical in all 10 samples tested and were also identical to ITS sequences of eight previously studied O. neolycopersici specimens. The AFLP analysis revealed a high genetic diversity in O. neolycopersici and indicated that all 17 samples represented different genotypes. This might suggest the existence of either a yet unrevealed sexual reproduction or other genetic mechanisms that maintain a high genetic variability in O. neolycopersici. No clear correlation was found between the virulence and the AFLP patterns of the O. neolycopersici isolates studied. The relationship between O. neolycopersici and powdery mildew anamorphs infecting Aquilegia vulgaris, Chelidonium majus, Passiflora caerulea, and Sedum alboroseum was also investigated. These anamorphs are morphologically indistinguishable from and phylogenetically closely related to O. neolycopersici. The crossinoculation tests and the analyses of ITS sequences and AFLP patterns jointly indicated that the powdery mildew anamorphs collected from the above mentioned plant species all represent distinct, but closely related species according to the phylogenetic species recognition. All these species were pathogenic only to their original host plant species, except O. neolycopersici which infected S. alboroseum, tobacco, petunia, and Arabidopsis thaliana, in addition to tomato, in cross-inoculation tests. This is the first genome-wide study that investigates the relationships among powdery mildews that are closely related based on ITS sequences and morphology. The results indicate that morphologically indistinguishable powdery mildews that differed in only one to five single nucleotide positions in their ITS region are to be considered as different taxa with distinct host ranges.

  • formation of conidial pseudochains by tomato powdery mildew Oidium neolycopersici
    Plant Disease, 2006
    Co-Authors: Wataru Oichi, Yoshinori Matsuda, Teruo Nonomura, Hideyoshi Toyoda, Ling Xu, Shinichi Kusakari
    Abstract:

    ABSTRACT The formation of conidial pseudochains by the tomato powdery mildew Oidium neolycopersici on tomato leaves was monitored using a high-fidelity digital microscope. Individual living conidiophores that formed mature conidial cells at their apex were selected for observation. The conidial cells were produced during repeated division and elongation by the generative cells of the conidiophores. Under weak wind conditions (0.1 m/s), these conidial cells did not separate from each other to produce a chain of conidial cells (pseudochain). The pseudochains dropped from the conidiophores once four conidial cells were connected. The conidiophores resumed conidium production, followed by another cycle of pseudochain formation. The formation of pseudochains by tomato powdery mildew was not influenced by the ambient relative humidity. On the other hand, the conidial cells produced were easily wind dispersed without forming pseudochains when conidiophores were exposed to stronger winds (1.0 m/s). The present st...

  • consecutive monitoring for conidiogenesis by Oidium neolycopersici on tomato leaves with a high fidelity digital microscope
    Journal of General Plant Pathology, 2004
    Co-Authors: Wataru Oichi, Takeshi Sameshima, Yoshinori Matsuda, Teruo Nonomura, Koji Kakutani, Shinichi Kusakari, Hiroaki Nishimura, Hideyoshi Toyoda
    Abstract:

    Conidiogenesis by Oidium neolycopersici KTP-01 on tomato leaves was vitally monitored with a high-fidelity digital microscope. Conidiophores were initially formed 3 days after inoculation and then elongated to a maximum length within at least 12 h. The apical part was split into two cells after two successive septations, accompanied by apical expansion. These cells subsequently developed into primary and secondary conidia. An additional septation at the stem portion of the conidiophores produced a generative and a foot cell. Subsequent conidiation occurred during repeated cycles of splitting of the generative cell, maturation of the apical cell into a conidium, and abstriction of the conidium. To our knowledge, this report is the first on the developmental process of conidiogenesis by powdery mildew on host leaves as revealed with the digital microscope.

  • Cytological events in tomato leaves inoculated with conidia of Blumeria graminis f. sp. hordei and Oidium neolycopersici KTP-01
    Journal of General Plant Pathology, 2004
    Co-Authors: Takeshi Sameshima, Koichi Kashimoto, Yoshinori Matsuda, Teruo Nonomura, Koji Kakutani, Kengo Nakata, Shinichi Kusakari, Keiko Kida, Hideyoshi Toyoda
    Abstract:

    Leaves of tomato and barley were inoculated with conidia of Blumeria graminis f. sp. hordei race 1 (R1) or Oidium neolycopersici (KTP-01) to observe cytological responses in search of resistance to powdery mildew. Both conidia formed appressoria at similar rates on tomato or barley leaves, indicating that no resistance was expressed during the prepenetration stage of these fungi. On R1-inoculated tomato leaves, appressoria penetrated the papillae, but subsequent haustorium formation was inhibited by hypersensitive necrosis in the invaded epidermal cells. On the other hand, KTP-01 (pathogenic to tomato leaves) successfully developed functional haustoria in epidermal cells to elongate secondary hyphae, although the hyphal elongation from some conidia was later suppressed by delayed hypersensitive necrosis in some haustorium-harboring epidermal cells. Thus, the present study indicated that the resistance of tomato to powdery mildew fungi was associated with a hypersensitive response in invaded epidermal cells but not the prevention of fungal penetration through host papilla.

  • infectivity of a japanese isolate of Oidium neolycopersici ktp 01 to a european tomato cultivar resistant to o lycopersici
    Journal of General Plant Pathology, 2003
    Co-Authors: Koichi Kashimoto, Takeshi Sameshima, Yoshinori Matsuda, Teruo Nonomura, Wataru Oichi, Koji Kakutani, Kengo Nakata, Shinichi Kusakari, Hideyoshi Toyoda
    Abstract:

    The infectivity of a Japanese isolate of tomato powdery mildew, Oidium neolycopersici KTP-01, to tomato cultivars was examined using a resistant cultivar Grace bred in The Netherlands to O. lycopersici, which was recently proposed to be renamed O. neolycopersici. Grace was severely infected with KTP-01, and its susceptibility was similar to that on susceptible tomato cultivars Moneymaker and Ponderosa, suggesting that KTP-01 differs in pathogenicity on tomatoes from those of European and American isolates.

Levente Kiss - One of the best experts on this subject based on the ideXlab platform.

  • first detection of tomato powdery mildew caused by Oidium neolycopersici in south africa
    South African Journal of Botany, 2015
    Co-Authors: Ales Lebeda, B Mieslerova, Levente Kiss, Tunde Jankovics, E J Van Der Linde
    Abstract:

    Oidium neolycopersici has a world-wide distribution causing severe epidemics mainly on greenhouse tomatoes. Currently, only Leveillula taurica has been reported on tomato from South Africa. However, another powdery mildew species on tomato was found recently. Based on morphological comparison and molecular analysis, its identity was confirmed as O. neolycopersici. The possible means of introduction and other aspects of this finding are discussed.

  • first report of powdery mildew Oidium sp on pincushion flower scabiosa columbaria in new york
    Plant Disease, 2009
    Co-Authors: Tunde Jankovics, Levente Kiss, R E Niks, Margery L Daughtrey
    Abstract:

    Scabiosa columbaria (Dipsacaceae) is a popular perennial ornamental in the United States. It is native to Europe and was introduced to North America by nursery trade only recently. In the spring of 2006, symptoms of powdery mildew infection were observed on overwintered plants of S. columbaria cv. Butterfly Blue in a nursery in Cutchogue, NY. White powdery mildew mycelia with abundant sporulation were observed on upper and lower leaf surfaces. The portions of leaves with powdery mildew colonies often showed purplish discoloration. Conidia were cylindric to doliiform, measured 20 to 33 × 10 to 15 μm, and were produced singly on 60 to 130 μm long conidiophores consisting of a foot-cell measuring 20 to 50 × 6 to 10 μm, followed by one to three, 12 to 40 μm long cells. Hyphal appressoria were lobed or multilobed. The teleomorph stage was not found. On the basis of these characteristics, the pathogen was identified as an Oidium sp. belonging to the subgenus PseudOidium. Recently, an anamorphic powdery mildew f...

  • Oidium neolycopersici intraspecific variability inferred from amplified fragment length polymorphism analysis and relationship with closely related powdery mildew fungi infecting various plant species
    Phytopathology, 2008
    Co-Authors: Tunde Jankovics, Marc Bardin, Philippe C Nicot, Yoshinori Matsuda, Hideyoshi Toyoda, R E Niks, Gabor M Kovacs, Levente Kiss
    Abstract:

    Jankovics, T., Bai, Y., Kovacs, G. M., Bardin, M., Nicot, P. C., Toyoda, H., Matsuda, Y., Niks, R. E., and Kiss, L. 2008. Oidium neolycopersici: Intraspecific variability inferred from amplified fragment length polymorphism analysis and relationship with closely related powdery mildew fungi infecting various plant species. Phytopathology 98:529-540. Previous works indicated a considerable variation in the pathogenicity, virulence, and host range of Oidium neolycopersici isolates causing tomato powdery mildew epidemics in many parts of the world. In this study, rDNA internal transcribed spacer (ITS) sequences, and amplified fragment length polymorphism (AFLP) patterns were analyzed in 17 O. neolycopersici samples collected in Europe, North America, and Japan, including those which overcame some of the tomato major resistance genes. The ITS sequences were identical in all 10 samples tested and were also identical to ITS sequences of eight previously studied O. neolycopersici specimens. The AFLP analysis revealed a high genetic diversity in O. neolycopersici and indicated that all 17 samples represented different genotypes. This might suggest the existence of either a yet unrevealed sexual reproduction or other genetic mechanisms that maintain a high genetic variability in O. neolycopersici. No clear correlation was found between the virulence and the AFLP patterns of the O. neolycopersici isolates studied. The relationship between O. neolycopersici and powdery mildew anamorphs infecting Aquilegia vulgaris, Chelidonium majus, Passiflora caerulea, and Sedum alboroseum was also investigated. These anamorphs are morphologically indistinguishable from and phylogenetically closely related to O. neolycopersici. The crossinoculation tests and the analyses of ITS sequences and AFLP patterns jointly indicated that the powdery mildew anamorphs collected from the above mentioned plant species all represent distinct, but closely related species according to the phylogenetic species recognition. All these species were pathogenic only to their original host plant species, except O. neolycopersici which infected S. alboroseum, tobacco, petunia, and Arabidopsis thaliana, in addition to tomato, in cross-inoculation tests. This is the first genome-wide study that investigates the relationships among powdery mildews that are closely related based on ITS sequences and morphology. The results indicate that morphologically indistinguishable powdery mildews that differed in only one to five single nucleotide positions in their ITS region are to be considered as different taxa with distinct host ranges.

  • Oidium longipes a new powdery mildew fungus on petunia in the usa a potential threat to ornamental and vegetable solanaceous crops
    Plant Disease, 2008
    Co-Authors: Levente Kiss, Gabor M Kovacs, Tiinde Jankovics, Margery L Daughtrey
    Abstract:

    ABSTRACT This is the first North American report of Oidium longipes, an anamorphic powdery mildew species described recently in Europe. It was found on vegetatively propagated petunia grown in a commercial greenhouse in New Jersey, USA, where it caused a rapidly spreading disease. The pathogen might have originated offshore and may have already been distributed in the United States through horticultural trade. During field surveys in Europe, it was found on petunia in Hungary and Austria as well; this is the first report of O. longipes from these two countries. A detailed light microscopy study of American and European specimens of O. longipes, including freshly collected samples and authentic herbarium specimens, revealed that its conidiophore morphology is more variable than illustrated in the original species description or in subsequent works. Microcycle conidiation, a process not yet known to occur in powdery mildews, was repeatedly observed in O. longipes. The rDNA internal transcribed spacer (ITS) ...

  • molecular identification of Oidium neolycopersici as the causal agent of the recent tomato powdery mildew epidemics in north america
    Plant Disease, 2005
    Co-Authors: Levente Kiss, Susumu Takamatsu, James H Cunnington
    Abstract:

    A previous morphological study of Oidium anamorphs responsible for the recent tomato (Lycopersicon esculentum) powdery mildew outbreaks worldwide suggested that, despite controversial data in the literature, the North American epidemics were caused solely by a newly erected species, O. neolycopersici. We report here the first molecular evidence that the North American anamorphs do belong to O. neolycopersici. The internal transcribed spacer sequences of the North American anamorphs of this study were identical with those of three Japanese and four European specimens of O. neolycopersici. A morphological study confirmed that all the North American Oidium anamorphs included in this study produced conidia singly, similar to O. neolycopersici. These fungi were readily distinguished from O. lycopersici, which produces conidia in chains and is known to infect tomato only in Australia. The phylogenetic analysis showed that O. neolycopersici is a distinct powdery mildew species, and it is neither identical nor closely related to any known polyphagous species of the Erysiphaceae. Apparently, it was introduced into the United States and Canada only in the 1990s, but its origin is still unknown.

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