scholarly journals Inheritance of resistance to downy mildew (Pseudoperonospora cubensis) in muskmelon (Cucumis melo). II. Generation means analysis of 5 genitors

Agronomie ◽  
1994 ◽  
Vol 14 (4) ◽  
pp. 249-257 ◽  
Author(s):  
C. Épinat ◽  
M. Pitrat
Keyword(s):  
Downy Mildew ◽  
Cucumis Melo ◽  
Pseudoperonospora Cubensis ◽  
Inheritance Of Resistance ◽  
Generation Means ◽  
Generation Means Analysis

scholarly journals Field Response of Cucurbit Hosts to Pseudoperonospora cubensis in Michigan

Plant Disease ◽  
2015 ◽  
Vol 99 (5) ◽  
pp. 676-682 ◽  
Author(s):  
M. C. Cespedes-Sanchez ◽  
R. P. Naegele ◽  
C. S. Kousik ◽  
M. K. Hausbeck
Keyword(s):  
Downy Mildew ◽  
Cucumis Melo ◽  
Disease Onset ◽  
Research Field ◽  
Pseudoperonospora Cubensis ◽  
Plant Introductions ◽  
Disease Progress ◽  
Pickling Cucumber ◽  
Progress Curve ◽  
Significant Disease

Downy mildew, caused by Pseudoperonospora cubensis, is a severe foliar disease of many cucurbit crops worldwide. Forty-one cucurbit cultigens (commercial cultivars and plant introductions) from five genera (Cucumis, Citrullus, Cucurbita, Lagenaria, and Luffa) were assessed for susceptibility to P. cubensis in a research field exposed to natural inoculum in Michigan. Eight cultigens from a differential set for pathotype determination were included within the 41 cultigens to detect changes in dominant P. cubensis pathotypes present. No pathotype differences were found between 2010 and 2011. Cucumis melo cultigen MR-1 was less susceptible to Michigan P. cubensis populations than other C. melo cultigens. No symptoms or signs of infection were detected on cultigens of Cucurbita moschata and C. pepo. Disease onset was later in 2011 than 2010; greater than 90% disease severity in pickling cucumber ‘Vlaspik’ was observed in both years. This study confirmed that Cucumis is the most susceptible cucurbit genus, while Citrullus and Cucurbita cultigens were the least susceptible genera to populations of P. cubensis in Michigan. Area under the disease progress curve values indicated that disease progress was limited on all Citrullus cultigens compared with Cucumis cultigens, and pathogen sporulation was not detected under field conditions. Future studies should evaluate the ability of a reduced fungicide program to control downy mildew on less susceptible Cucumis melo ‘Edisto 47’, ‘Primo’, ‘Athena’, ‘Strike’, ‘Ananas’, ‘Banana’, and ‘Tam-Dew’. Many of the melon cultivars evaluated were selected on the basis of reported resistance to downy mildew, yet they showed significant disease symptoms. It is important to evaluate candidate cultigens for resistance to local P. cubensis populations.

scholarly journals Inheritance of Resistance to Anthracnose Caused by Colletotrichum coccodes in Tomato

1998 ◽  
Vol 123 (5) ◽  
pp. 832-836 ◽  
Author(s):  
John R. Stommel ◽  
Kathleen G. Haynes
Keyword(s):  
Gene Action ◽  
Colletotrichum Coccodes ◽  
Inheritance Of Resistance ◽  
Dominance Model ◽  
Narrow Sense Heritability ◽  
Breeding Lines ◽  
Anthracnose Resistance ◽  
Generation Means ◽  
Generation Means Analysis ◽  
Backcross Populations

Inheritance of resistance to tomato anthracnose caused by Colletotrichum coccodes (Wallr.) S.J. Hughes was evaluated in parental, F1, F2, and backcross populations developed from crosses between adapted resistant (88B147) and susceptible (90L24) tomato (Lycopersicon esculentum Mill.) breeding lines. Resistance was evaluated via measurement of lesion diameters in fruit collected from field-grown plants and puncture inoculated in a shaded greenhouse. Backcross and F2 populations exhibited continuous distributions suggesting multigenic control of anthracnose resistance. Anthracnose resistance was partially dominant to susceptibility. Using generation means analysis, gene action in these populations was best explained by an additive-dominance model with additive × additive epistatic effects. A broad-sense heritability (H) of 0.42 and narrow-sense heritability (h2) of 0.004 was estimated for resistance to C. coccodes. One gene or linkage group was estimated to control segregation for anthracnose resistance in the cross of 90L24 × 88B147.

scholarly journals Bioactive compound profile of melon leaf extract (Cucumis melo L. ‘Hikapel’) infected by downy mildew

2019 ◽  
Vol 20 (11) ◽  
Author(s):  
Ozie Akbar Pratama ◽  
WORO ANINDITO SRI TUNJUNG ◽  
SUTIKNO SUTIKNO ◽  
BUDI SETIADI DARYONO
Keyword(s):  
Downy Mildew ◽  
Cucumis Melo ◽  
Leaf Extract ◽  
Methyl Ricinoleate ◽  
Insulin Level ◽  
Bioactive Compound ◽  
Pseudoperonospora Cubensis ◽  
Leaf Powder ◽  
Bioactive Content ◽  
Cucumis Melo L

Abstract. Pratama OA, Tunjung WAS, Sutikno, Daryono BS. 2019. Bioactive compound profile of melon leaf extract (Cucumis melo L. ‘Hikapel’) infected by downy mildew. Biodiversitas 20: 3448-3453. Plants express specific secondary metabolites (phytoalexin) in response to infection. Downy Mildew which infects melon plants (Cucumis melo L. ‘Hikapel’) caused by Pseudoperonospora cubensis Rostovtsev. Hikapel is one of superior melon cultivar produced from research in the Laboratory of Genetics, Faculty of Biology, Universitas Gadjah Mada, Yogyakarta, Indonesia. Bioactive content of Hikapel melon leaf under normal condition and infected by Downy Mildew yet to be researched. This research aims to screen bioactive profile of Hikapel leaf extract that has potential as phytomedicine. Leaf extract is compared between healthy plants and infected by Downy Mildew. Dried melon leaf was powdered using mortar and pestle. Leaf powder was extracted using hexane solvent. Extract was analyzed using a Shimadzu GCMS-QP2010S. Analysis found useful compounds like phytol, methyl ricinoleate, methyl linoleate, methyl stearate, and 1-hexacosanol. with therapeutic activity such as antibacterial, antifungal, antioxidant, antiinflammatory, antidiuretic, antidiarrheal, lowering blood LDL-C level, insulin level booster, antiproliferative, and anticancer. Some bioactive compounds are only synthesized in Hikapel melon leaf under stress conditions.

scholarly journals Formation and Infectivity of Oospores of Pseudoperonospora cubensis, the Causal Agent of Downy Mildew in Cucurbits

Plant Disease ◽  
2011 ◽  
Vol 95 (7) ◽  
pp. 874-874 ◽  
Author(s):  
Y. Cohen ◽  
A. E. Rubin ◽  
M. Galperin
Keyword(s):  
United States ◽  
Downy Mildew ◽  
Cucumis Melo ◽  
The United States ◽  
Pseudoperonospora Cubensis ◽  
Prolonged Incubation ◽  
Field Isolates ◽  
F1 Progeny ◽  
Detached Leaves ◽  
Growth Chambers

The oomycete Pseudoperonospora cubensis attacks members of the Cucurbitaceae, causing severe foliage damage especially to cucumber and melon. Recently, new pathotypes of this oomycete appeared in Israel (2) and Italy (1) and highly aggressive isolates appeared in the United States (3). Since oospores of P. cubensis were rarely seen and sexual propagation by oospores was never reported (4), it is assumed that it propagates clonally by sporangia. Here we report on sexual reproduction of P. cubensis under controlled conditions in the laboratory. We found that field isolates belonging to the old pathotype 3 or to the new pathotype 6 (2) inoculated singly onto detached leaves of cucurbits in growth chambers at 15 or 20°C produced no oospores, even after prolonged incubation periods. However, when sporangia of some paired field isolates were mixed together at a 1:1 ratio, similarly inoculated onto detached leaves, and incubated at 15 or 20°C, numerous oospores (up to ~300/cm2) were formed in the mesophyll within 6 to 11 days, depending on the isolates pair, the host inoculated, and temperature. Oospores were also formed at 12.5°C but not at 25°C. Oospores developed in intact plants when kept at 15 or 20°C under a humidity-saturated atmosphere during disease development. Oospores were round, light brown to brown with an average diameter of ~40 μm. Oospores were produced in Cucumis sativum (cvs. Nadiojni and Dalila) and Cucumis melo (cvs. Ananas-Yokneam and Ein-Dor) but not in Cucurbita pepo (cv. Arlika, Beiruti), C. moschata (cv. Dalorit), or C. maxima (cv. Tripoli). To verify that oospores are infective, cucumber or melon leaves containing oospores were homogenized in water. The homogenate was twice brought to dryness at 25 to 30°C in petri dishes to differentially kill the vegetative structures of the pathogen (sporangia, cystospores, zoospores, and mycelia), resuspended in water, and inoculated onto detached leaves of various cucurbits in growth chambers at 15 or 20°C. Downy mildew lesions carrying sporangia appeared within 7 to 20 days in leaves of Cucumis sativum, Cucumis melo, and C. moschata but not in C. pepo or C. maxima. The recombinant origin of the F1 offspring isolates was confirmed by mefenoxam sensitivity tests, random amplified polymorphic DNA, and simple sequence repeat analyses. F1 progeny isolates of some crosses lost pathogenicity to C. moschata or C. maxima, toward which one of their parents was pathogenic, while others gained pathogenicity to Luffa cylindrica or Citrullus lanatus toward which neither parent was pathogenic. Data confirmed that isolates of P. cubensis can mate to produce oospores, especially under constant humidity conditions; such oospores are infective to cucurbits and F1 progeny isolates show altered sensitivity to fungicides or altered host range relative to their parents. To our knowledge, this is the first report of oospore formation by P. cubensis in the laboratory and on their pathogenicity to cucurbits. Reasons for the parallel appearance of new pathotypes of P. cubensis in Israel in 2002 (2) and Italy in 2003 (1) and the reemergence of highly aggressive isolates of the pathogen in the United States in 2004 (3) are not known. They may be related to oospore production and sexual recombination in P. cubensis. References: (1) C. Cappelli et al. Plant Dis. 87:449, 2003. (2) Y. Cohen et al. Phytoparasitica 31:458, 2003. (3) G. J. Holmes et al. Am. Veg. Grower. February, 14-15, 2006. (4) A. Lebeda and Y. Cohen. Eur. J. Plant Pathol.129:157, 2011.

scholarly journals Evaluation of Melon Germplasm for Resistance to Downy Mildew

HortScience ◽  
1992 ◽  
Vol 27 (5) ◽  
pp. 434-436 ◽  
Author(s):  
Claude E. Thomas ◽  
E.L. Jourdain
Keyword(s):  
Downy Mildew ◽  
Cucumis Melo ◽  
Disease Index ◽  
Pseudoperonospora Cubensis ◽  
Reaction Type ◽  
Plant Introductions ◽  
Resistant Reaction ◽  
Moderately Resistant

Field evaluations for resistance against downy mildew, incited by Pseudoperonospora cubensis [(Berk. and Cart.) Rostow], were conducted on 942 U.S. Plant Introductions (PI) of Cucumis melo L. (melon). A disease index (DI) was calculated for each entry. Based on DI, PI 124112 was highly resistant (DI = 3.7), and PIs 124111, 122847, 124210, 145594, and 165525 were resistant (DI = 3.0, 2.8, 2.6, 2.7, and 2.5, respectively). PIs 124111 and 124112 had one or more plants that exhibited a highly resistant reaction type (RT 4). Resistant (RT 3) plants were identified in 31 accessions, and 49 accessions bad moderately resistant (RT 2) plants.

scholarly journals Reaction of melon genotypes to the gummy stem blight and the downy mildew

2009 ◽  
Vol 27 (2) ◽  
pp. 160-165 ◽  
Author(s):  
Gil R dos Santos ◽  
Manoel D de Castro Neto ◽  
Leandro N Ramos ◽  
Adalberto C Café-Filho ◽  
Ailton Reis ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Cucumis Melo ◽  
Significant Variation ◽  
Natural Infection ◽  
Pseudoperonospora Cubensis ◽  
Didymella Bryoniae ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Stem Infection ◽  
Leaf Infection

The gummy stem blight (Didymella bryoniae) and the downy mildew (Pseudoperonospora cubensis) are two foremost melon (Cucumis melo) diseases, considering their effects on yield and fruit quality. Despite the importance of such diseases, relatively few studies have been done so far on the identification of resistance sources to D. bryoniae and P. cubensis in Brazil. This work aimed at evaluating the resistance of commercial melon genotypes to the gummy stem blight and the downy mildew. Firstly, the most aggressive and representative D. bryoniae isolate was selected. Subsequently, the resistance of 86 melon genotypes to stem infection was studied upon greenhouse conditions by inoculating with the previously selected isolate. Afterwards, the resistance to mildew and leaf infection by D. bryoniae of 28 melon genotypes was evaluated in the field, under natural infection. In the greenhouse, all 86 melon genotypes were infected and showed stem infection symptoms caused by D. bryoniae four days after inoculation. Nevertheless, a significant variation on the resistance levels of the melon genotypes was found. Under field conditions and natural inoculation, genotypes Taslaki and Sary Juliabi were the most susceptible to leaf infection by D. bryoniae, significantly differing from the other genotypes. The lowest levels of susceptibility were identified in genotypes Perlita Busle S1, Valenciano Elíptico, Glaver, MR1, and 2526. All genotypes were susceptible to the downy mildew, albeit differing in susceptibility levels.

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