The tomato powdery mildew fungus Oidium neolycopersici

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 study successfully demonstrated that the pathogen required wind to disperse progeny conidia from the conidiophores and produced conidial pseudochains when the wind was below a critical level, independent of high relative humidity as reported previously.

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Ampelomyces strains isolated from diverse powdery mildew hosts in Japan: Their phylogeny and mycoparasitic activity, including timing and quantifying mycoparasitism of Pseudoidium neolycopersici on tomato

PLoS ONE ◽

10.1371/journal.pone.0251444 ◽

2021 ◽

Vol 16 (5) ◽

pp. e0251444

Author(s):

Márk Z. Németh ◽

Yuusaku Mizuno ◽

Hiroki Kobayashi ◽

Diána Seress ◽

Naruki Shishido ◽

...

Keyword(s):

Powdery Mildew ◽

Host Plants ◽

Morphological Characteristics ◽

Post Inoculation ◽

Powdery Mildew Fungus ◽

Rdna Its ◽

Pseudoidium Neolycopersici ◽

Tomato Powdery Mildew ◽

Internal Transcribed Spacer Rdna ◽

Complete Collapse

A total of 26 Ampelomyces strains were isolated from mycelia of six different powdery mildew species that naturally infected their host plants in Japan. These were characterized based on morphological characteristics and sequences of ribosomal DNA internal transcribed spacer (rDNA-ITS) regions and actin gene (ACT) fragments. Collected strains represented six different genotypes and were accommodated in three different clades of the genus Ampelomyces. Morphology of the strains agreed with that of other Ampelomyces strains, but none of the examined characters were associated with any groups identified in the genetic analysis. Five powdery mildew species were inoculated with eight selected Ampelomyces strains to study their mycoparasitic activity. In the inoculation experiments, all Ampelomyces strains successfully infected all tested powdery mildew species, and showed no significant differences in their mycoparasitic activity as determined by the number of Ampelomyces pycnidia developed in powdery mildew colonies. The mycoparasitic interaction between the eight selected Ampelomyces strains and the tomato powdery mildew fungus (Pseudoidium neolycopersici strain KTP-03) was studied experimentally in the laboratory using digital microscopic technologies. It was documented that the spores of the mycoparasites germinated on tomato leaves and their hyphae penetrated the hyphae of Ps. neolycopersici. Ampelomyces hyphae continued their growth internally, which initiated the atrophy of the powdery mildew conidiophores 5 days post inoculation (dpi); caused atrophy 6 dpi; and complete collapse of the parasitized conidiphores 7 dpi. Ampelomyces strains produced new intracellular pycnidia in Ps. neolycopersici conidiophores ca. 8–10 dpi, when Ps. neolycopersici hyphae were successfully destroyed by the mycoparasitic strain. Mature pycnidia released spores ca. 10–14 dpi, which became the sources of subsequent infections of the intact powdery mildew hyphae. Mature pycnidia contained each ca. 200 to 1,500 spores depending on the mycohost species and Ampelomyces strain. This is the first detailed analysis of Ampelomyces strains isolated in Japan, and the first timing and quantification of mycoparasitism of Ps. neolycopersici on tomato by phylogenetically diverse Ampelomyces strains using digital microscopic technologies. The developed model system is useful for future biocontrol and ecological studies on Ampelomyces mycoparasites.

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Determination of UV action spectra affecting the infection process of Oidium neolycopersici, the cause of tomato powdery mildew

Journal of Photochemistry and Photobiology B Biology ◽

10.1016/j.jphotobiol.2016.01.009 ◽

2016 ◽

Vol 156 ◽

pp. 41-49 ◽

Cited By ~ 15

Author(s):

Aruppillai Suthaparan ◽

Knut Asbjørn Solhaug ◽

Arne Stensvand ◽

Hans Ragnar Gislerød

Keyword(s):

Powdery Mildew ◽

Infection Process ◽

Oidium Neolycopersici ◽

Action Spectra ◽

Tomato Powdery Mildew

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Genome-Wide Study of the Tomato SlMLO Gene Family and Its Functional Characterization in Response to the Powdery Mildew Fungus Oidium neolycopersici

Frontiers in Plant Science ◽

10.3389/fpls.2016.00380 ◽

2016 ◽

Vol 7 ◽

Cited By ~ 23

Author(s):

Zheng Zheng ◽

Michela Appiano ◽

Stefano Pavan ◽

Valentina Bracuto ◽

Luigi Ricciardi ◽

...

Keyword(s):

Powdery Mildew ◽

Gene Family ◽

Functional Characterization ◽

Oidium Neolycopersici ◽

Powdery Mildew Fungus ◽

Genome Wide ◽

Genome Wide Study

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Cloning of the Cytochrome b Gene From the Tomato Powdery Mildew Fungus Leveillula taurica Reveals High Levels of Allelic Variation and Heteroplasmy for the G143A Mutation

Frontiers in Microbiology ◽

10.3389/fmicb.2019.00663 ◽

2019 ◽

Vol 10 ◽

Cited By ~ 4

Author(s):

Sandra Mosquera ◽

Li-Hung Chen ◽

Brenna Aegerter ◽

Eugene Miyao ◽

Anthony Salvucci ◽

...

Keyword(s):

Powdery Mildew ◽

Cytochrome B ◽

Allelic Variation ◽

Cytochrome B Gene ◽

Powdery Mildew Fungus ◽

Leveillula Taurica ◽

Tomato Powdery Mildew

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A New Spore Precipitator with Polarized Dielectric Insulators for Physical Control of Tomato Powdery Mildew

Phytopathology ◽

10.1094/phyto-96-0967 ◽

2006 ◽

Vol 96 (9) ◽

pp. 967-974 ◽

Cited By ~ 22

Author(s):

Yoshinori Matsuda ◽

Hiroki Ikeda ◽

Nobuyuki Moriura ◽

Norio Tanaka ◽

Kunihiko Shimizu ◽

...

Keyword(s):

Powdery Mildew ◽

Copper Wire ◽

Electrostatic Force ◽

Oidium Neolycopersici ◽

Powdery Mildew Fungus ◽

Tomato Plants ◽

Wire Conductor ◽

Rapid Spread ◽

Electrostatic Generator ◽

Entire Experiment

In an attempt to physically protect greenhouse tomato plants from the powdery mildew fungus Oidium neolycopersici, we developed a new electrostatic spore precipitator in which a copper wire conductor is linked to an electrostatic generator and covered with a transparent acrylic cylinder (insulator). The conductor was negatively charged by the generator, and the electrostatic field created by the conductor was used to dielectrically polarize the insulator cylinder. The dielectrically polarized cylinder also produced an electrostatic force without a spark discharge. This force was directly proportional to the potential applied to the conductor and was used to attract conidia of the pathogen. The efficacy of this spore precipitator in protecting hydroponically cultured tomato plants from powdery mildew was evaluated in the greenhouse. The hydroponic culture troughs were covered with a cubic frame installed with the spore precipitator, and the disease progress on precipitator-guarded and unguarded seedlings was traced after the conidia were disseminated mechanically from inoculum on tomato plants. Seedlings in the guarded troughs remained uninfected during the entire experiment, in spite of rapid spread of the disease to all leaves of the unguarded seedlings.

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Tomato Defense to Oldium neolycopersici: Dominant OI Genes Confer Isolate-Dependent Resistance Via a Different Mechanism Than Recessive oI-2

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-18-0354 ◽

2005 ◽

Vol 18 (4) ◽

pp. 354-362 ◽

Cited By ~ 64

Author(s):

Yuling Bai ◽

Ron van der Hulst ◽

Guusje Bonnema ◽

Thierry C. Marcel ◽

Fien Meijer-Dekens ◽

...

Keyword(s):

Powdery Mildew ◽

Resistance Genes ◽

Resistance Mechanism ◽

Recessive Gene ◽

Defense Responses ◽

Oidium Neolycopersici ◽

Mechanism Of Resistance ◽

Tomato Chromosome ◽

Tomato Powdery Mildew ◽

Important Disease

Tomato powdery mildew caused by Oidium neolycopersici has become a globally important disease of tomato (Lycopersicon esculentum). To study the defense responses of tomato triggered by tomato powdery mildew, we first mapped a set of resistance genes to O. neolycopersici from related Lycopersicon species. An integrated genetic map was generated showing that all the dominant resistance genes (Ol-1, Ol-3, Ol-4, Ol-5, and Ol-6) are located on tomato chromosome 6 and are organized in three genetic loci. Then, near-isogenic lines (NIL) were produced that contain the different dominant Ol genes in a L. esculentum genetic background. These NIL were used in disease tests with local isolates of O. neolycopersici in different geographic locations, demonstrating that the resistance conferred by different Ol genes was isolate-dependent and, hence, may be race-specific. In addition, the resistance mechanism was analyzed histologically. The mechanism of resistance conferred by the dominant Ol genes was associated with hypersensitive respo-nse, which varies in details depending on the Ol-gene in the NIL, while the mechanism of resistance governed by the recessive gene ol-2 on tomato chromosome 4 was associated with papillae formation.

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