scholarly journals Formation of Conidial Pseudochains by Tomato Powdery Mildew Oidium neolycopersici

Plant Disease ◽  
2006 ◽  
Vol 90 (7) ◽  
pp. 915-919 ◽  
Author(s):  
W. Oichi ◽  
Y. Matsuda ◽  
T. Nonomura ◽  
H. Toyoda ◽  
L. Xu ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Powdery Mildew ◽  
Critical Level ◽  
Oidium Neolycopersici ◽  
Ambient Relative Humidity ◽  
Digital Microscope ◽  
Tomato Powdery Mildew ◽  
A Chain ◽  
Weak Wind ◽  
Generative Cells

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.

scholarly journals Occurrence of powdery mildew disease of Gerbera in Kerala

2018 ◽  
Vol 13 (2) ◽  
pp. 217-220
Author(s):  
N M Praveen ◽  
Reshmy Vijayaraghavan ◽  
S Beena ◽  
S Krishnan
Keyword(s):  
Relative Humidity ◽  
Powdery Mildew ◽  
Weather Data ◽  
Slight Reduction ◽  
Erysiphe Cichoracearum ◽  
Powdery Mildew Disease ◽  
Golovinomyces Cichoracearum ◽  
A Chain ◽  
Cent Disease ◽  
Summer Decline

A purposive sampling survey on the hilly tracts of Wayanad, Kerala revealed the existence ofpowdery mildew disease in gerbera crops, grown under both protected and open field condition.Among the other fungal diseases of gerbera, powdery mildew disease causes decisive damageto the ornamental cut flower crop, thereby decline in the industrial value of the crop. Symptomof the disease include as white powdery mat on the upper surface of leaf lamina that graduallyturned pale yellow to brown. Powdery mildew existed in two locations of Wayanad viz.,Ambalavayal and Chulliyode where highest per cent disease severity (PDS) of 50.72 wasobserved at Chulliyode and 47.2 per cent was observed at Ambalavayal during November-December. In Ambalavayal, the disease was non-significant and no correlation existed betweenweather parameters and disease progress. But, in Chulliyode, correlation studies revealed thatit was significant with positive correlation to relative humidity and a reverse relation existedwith temperature and rainfall. The weather data clearly depicts that at a low rainfall of 96 mmand above average relative humidity of 80.27 per cent during November-December was thecongenial factor influencing the disease development. But during summer, decline in relativehumidity (78.37%) and rainfall (63.13 mm) caused a slight reduction in mean per cent diseaseseverity of 49.12 per cent and 33.6 per cent at Chulliyode and Ambalavayal respectively.Morohological and cultural characters of the pathogen depicts presence of two distinct organismviz., Golovinomyces cichoracearum (Erysiphe cichoracearum) and Podosphaera sp. as thecausative organism of the disease. Golovinomyces cichoracearumproduced hyaline, septatemycelia with globose conidia with irregular peripheral end formed in a chain and Podosphaerasp. produced superficial, hyaline, coenocytic mycelium with oval or ellipsoidal, catenate conidiawith dimension ranging from 22.1-30.18 x 13.36-18.08ìm formed in unbranched erectconidiophores.

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

2005 ◽  
Vol 18 (4) ◽  
pp. 354-362 ◽  
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.

scholarly journals An Avirulent Tomato Powdery Mildew Isolate Induces Localized Acquired Resistance to a Virulent Isolate in a Spatiotemporal Manner

2012 ◽  
Vol 25 (3) ◽  
pp. 372-378 ◽  
Author(s):  
Alireza Seifi ◽  
Teruo Nonomura ◽  
Yoshinori Matsuda ◽  
Hideyoshi Toyoda ◽  
Yuling Bai
Keyword(s):  
Powdery Mildew ◽  
Acquired Resistance ◽  
Epidermal Cells ◽  
Adjacent Cell ◽  
Advanced Technique ◽  
Tomato Plants ◽  
Digital Microscope ◽  
Tomato Powdery Mildew ◽  
Leucine Rich Repeat Protein ◽  
Virulence Spectrum

Hypersensitive response (HR) of plant cells to the attack of pathogens induces resistance to subsequent attacks by a broad spectrum of pathogens, leading to acquired resistance. In this study, we characterized the localized acquired resistance (LAR) in the epidermal cells of tomato. First, we report the discovery of a new isolate of tomato powdery mildew occurring in Japan, KTP-02, which has a different virulence spectrum compared with the previously-characterized isolate, KTP-01. Using these two isolates, we investigated LAR phenomenon in the epidermal cells of tomato plants carrying the Ol-4 resistance gene. Ol-4 encodes a nucleotide-binding site leucine-rich repeat protein that triggers HR in the epidermal cells in response to KTP-01 but not KTP-02. We mounted a single conidium of KTP-01 on a single tomato epidermal cell and then monitored the progress of HR in that cell by live microscopy. Once HR occurred in that cell, we mounted a single conidium of KTP-02 on cells adjacent to or at one-cell distance from the first challenged cells, in different time points. With a digital microscope, we consecutively tracked the progress of HR (i.e., induction of LAR) in those cells. Results showed that, in tomato plants carrying the Ol-4 gene, HR to KTP-01 results in induction of HR in the adjacent epidermal cells challenged with KTP-02. Our results show that LAR can be triggered only in adjacent cell layer and lasts 24 to 48 h after HR occurred in the first cell. We did not observe the reverse phenomenon, induced susceptibility to KTP-01 by KTP-02. Altogether, we report an advanced technique for investigating LAR phenomena, and provide data on spatiotemporal characteristics of LAR in tomato epidermal cells.

scholarly journals Identification of Individual Powdery Mildew Fungi Infecting Leaves and Direct Detection of Gene Expression by Single Conidium Polymerase Chain Reaction

2005 ◽  
Vol 95 (10) ◽  
pp. 1137-1143 ◽  
Author(s):  
Yoshinori Matsuda ◽  
Takeshi Sameshima ◽  
Nobuyuki Moriura ◽  
Kanako Inoue ◽  
Teruo Nonomura ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Nested Pcr ◽  
Direct Detection ◽  
Pcr Amplification ◽  
Rt Pcr ◽  
Oidium Neolycopersici ◽  
5.8S Rdna ◽  
Digital Microscope ◽  
Powdery Mildew Fungi

Greenhouse-grown tomato seedlings were inoculated naturally with two genera of powdery mildew conidia forming appressorial germ tubes that could not be differentiated by length alone. For direct identification, single germinated conidia were removed from leaves by means of a glass pipette linked to the manipulator of a high-fidelity digital microscope. This microscope enabled in vivo observation of the fungi without leaf decoloration or fungal staining. The isolated conidia were subjected to PCR amplification of the 5.8S rDNA and its adjacent internal transcribed spacer sequences followed by nested PCR to attain sensitivity high enough to amplify target nucleotide sequences (PCR/nested PCR). Target sequences from the conidia were completely coincident with those of the pathogen Oidium neolycopersici or Erysiphe trifolii (syn. Microsphaera trifolii), which is nonpathogenic on tomato. Using RT-PCR/nested PCR or multiplex RT-PCR/nested PCR, it was possible to amplify transcripts expressed in single conidia. Conidia at pre- and postgermination stages were removed individually from tomato leaves, and two powdery mildew genes were monitored. The results indicated that the β-tubulin homolog TUB2-ol was expressed at pre- and postgermination stages and the cutinase homolog CUT1-ol was only expressed postgermination. Combining digital microscopic micromanipulation and two-step PCR amplification is thus useful for investigation of individual propagules on the surface of plants.

The tomato powdery mildew fungus Oidium neolycopersici

2001 ◽  
Vol 2 (6) ◽  
pp. 303-309 ◽  
Author(s):  
Hannah Jones ◽  
John M. Whipps ◽  
Sarah Jane Gurr
Keyword(s):  
Powdery Mildew ◽  
Oidium Neolycopersici ◽  
Powdery Mildew Fungus ◽  
Tomato Powdery Mildew

scholarly journals Screening of Wild Lycopersicon Species for Resistance to Japanese Isolate of Tomato Powdery Mildew Oidium neolycopersici

2005 ◽  
Vol 55 (3) ◽  
pp. 355-360 ◽  
Author(s):  
Yoshinori Matsuda ◽  
Yoshinori Mori ◽  
Yohei Sakano ◽  
Masayoshi Nishida ◽  
Koji Tarumoto ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Japanese Isolate ◽  
Oidium Neolycopersici ◽  
Tomato Powdery Mildew

scholarly journals First detection of tomato powdery mildew caused by Oidium neolycopersici in South Africa

2015 ◽  
Vol 99 ◽  
pp. 153-157 ◽  
Author(s):  
A. Lebeda ◽  
B. Mieslerová ◽  
T. Jankovics ◽  
L. Kiss ◽  
E.J. Van der Linde
Keyword(s):  
South Africa ◽  
Powdery Mildew ◽  
Oidium Neolycopersici ◽  
Tomato Powdery Mildew

scholarly journals Biochemical and Molecular Mechanisms Involved in Monogenic Resistance Responses to Tomato Powdery Mildew

2007 ◽  
Vol 20 (9) ◽  
pp. 1161-1172 ◽  
Author(s):  
Chengwei Li ◽  
Guusje Bonnema ◽  
Daidi Che ◽  
Lin Dong ◽  
Pim Lindhout ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Molecular Mechanisms ◽  
Expression Patterns ◽  
Marker Gene ◽  
Sequence Information ◽  
Oidium Neolycopersici ◽  
Monogenic Resistance ◽  
Papilla Formation ◽  
Tomato Powdery Mildew ◽  
Incompatible Interactions

The monogenic genes Ol-1, ol-2, and Ol-4 confer resistance to tomato powdery mildew Oidium neolycopersici via different mechanisms. The biochemical mechanisms involved in these monogenic resistances were studied by monitoring through time the association of H2O2 and callose accumulation with hypersensitive response (HR) and papilla formation. Our results showed that H2O2 and callose accumulation are coupled with both Ol-1- and Ol-4–mediated HR-associated resistance as well as with the ol-2–mediated papillae-associated resistance. Further, the transcriptomal changes related to these monogenic resistances were studied by using cDNA-amplification fragment length polymorphism. The expression profiling clarified that 81% of DE-TDF (differentially expressed transcript-derived fragments) were up-regulated upon inoculation with O. neolycopersici in both the compatible and Ol-1–mediated incompatible interactions, though with a difference in expression timing. Of these DE-TDF, more than 70% were not detected in the Ol-4–mediated resistance, while 58% were expressed in the ol-2–mediated resistance, generally at later timepoints. Sequence information suggested that most of these DE-TDF are related to genes involved in either basal defense or establishment of compatibility. In addition, DE-TDF (19%) specifically expressed in different incompatible interactions were identified. Expression patterns of some DE-TDF and marker gene GluB suggested that papillae-associated resistance exploits a different defense pathway from that of HR-associated resistance.

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