{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/49606"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/49606","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Cucurbit Downy Mildew (Pseudoperonospora cubensis): Cucumber Resistance","abstract":"Pseudoperonospora cubensis (Bert. et Curt) Rost. is the causal agent of cucurbit downy mildew (CDM). It is the most damaging cucumber pathogen on the Eastern Shore of Virginia and eastern parts of the United States. Pseudoperonospora cubensis is an obligate oomycete pathogen, infecting crops within the Cucurbitaceae family. The disease is characterized by angular chlorotic lesions and a downy or felt-like appearance on the abaxial side of the leaf. Control of this pathogen includes use of resistant cucumber cultivars and costly fungicide programs. Continuous use has led to resistance to commonly used fungicides. This has become a major concern and in response, seed companies have developed cucumber cultivars which claim downy mildew resistance. This study evaluates different cucumber cultivars and assesses their level of resistance to CDM. The results indicate that an integrated management approach of reduced fungicide application and the use of resistant cultivars can suppress levels of CDM and yield a cucumber crop. Additionally, a molecular study was conducted, comparing the relative expression of genes encoding a basic PR-1 protein, a cytosolic ascorbate peroxidase protein and three resistance (R) gene proteins, in nineteen cultivars. All of the selected genes were analyzed using real-time PCR. The relative expression levels of the R-genes varied between cultivars. The basic PR-1 protein decreased expression in the majority of the cultivars, suggesting no involvement in the first twenty-four hours. Cytosolic ascorbate peroxidase relative expression levels suggest an increase in susceptible cultivars and a decrease in tolerant cultivars.","abstract_html":"Pseudoperonospora cubensis (Bert. et Curt) Rost. is the causal agent of cucurbit downy mildew (CDM). It is the most damaging cucumber pathogen on the Eastern Shore of Virginia and eastern parts of the United States. Pseudoperonospora cubensis is an obligate oomycete pathogen, infecting crops within the Cucurbitaceae family. The disease is characterized by angular chlorotic lesions and a downy or felt-like appearance on the abaxial side of the leaf. Control of this pathogen includes use of resistant cucumber cultivars and costly fungicide programs. Continuous use has led to resistance to commonly used fungicides. This has become a major concern and in response, seed companies have developed cucumber cultivars which claim downy mildew resistance. This study evaluates different cucumber cultivars and assesses their level of resistance to CDM. The results indicate that an integrated management approach of reduced fungicide application and the use of resistant cultivars can suppress levels of CDM and yield a cucumber crop. Additionally, a molecular study was conducted, comparing the relative expression of genes encoding a basic PR-1 protein, a cytosolic ascorbate peroxidase protein and three resistance (R) gene proteins, in nineteen cultivars. All of the selected genes were analyzed using real-time PCR. The relative expression levels of the R-genes varied between cultivars. The basic PR-1 protein decreased expression in the majority of the cultivars, suggesting no involvement in the first twenty-four hours. Cytosolic ascorbate peroxidase relative expression levels suggest an increase in susceptible cultivars and a decrease in tolerant cultivars.","abstract_has_math":false,"creators":["Cooper, Jessica G."],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Plant Pathology, Physiology, and Weed Science","degree_department":"Plant Pathology, Physiology, and Weed Science","school":null,"contributors":[],"advisors":[],"committee_chairs":["Rideout, Steven L."],"committee_members":["Donofrio, Nicole M.","Baudoin, Antonius B."],"year":2013,"date_issued":"2013-01-23","date_published":"2013-01-23","updated_at":"2026-07-22T22:20:41Z","subjects":["cucurbit downy mildew","cucumber","CSA 06724","cyazofamid","fluopicolide","PR-1","cytosolic ascorbate peroxidase","CSA06758","CSA06757"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:114"],"render_values":[{"text":"vt_gsexam:114","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/49606","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Rideout, Steven L."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Donofrio, Nicole M.","Baudoin, Antonius B."]},{"key":"dc:contributor.department","label":"Department","values":["Plant Pathology, Physiology, and Weed Science"]},{"key":"dc:creator","label":"Author","values":["Cooper, Jessica G."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-07-18T17:32:32Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-07-18T17:32:32Z"]},{"key":"dc:date.issued","label":"Date","values":["2013-01-23"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Plant Pathology, Physiology, and Weed Science"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["cucurbit downy mildew","cucumber","CSA 06724","cyazofamid","fluopicolide","PR-1","cytosolic ascorbate peroxidase","CSA06758","CSA06757"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:114"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/49606"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Pseudoperonospora cubensis (Bert. et Curt) Rost. is the causal agent of cucurbit downy mildew (CDM). It is the most damaging cucumber pathogen on the Eastern Shore of Virginia and eastern parts of the United States. Pseudoperonospora cubensis is an obligate oomycete pathogen, infecting crops within the Cucurbitaceae family. The disease is characterized by angular chlorotic lesions and a downy or felt-like appearance on the abaxial side of the leaf. Control of this pathogen includes use of resistant cucumber cultivars and costly fungicide programs. Continuous use has led to resistance to commonly used fungicides. This has become a major concern and in response, seed companies have developed cucumber cultivars which claim downy mildew resistance. This study evaluates different cucumber cultivars and assesses their level of resistance to CDM. The results indicate that an integrated management approach of reduced fungicide application and the use of resistant cultivars can suppress levels of CDM and yield a cucumber crop. Additionally, a molecular study was conducted, comparing the relative expression of genes encoding a basic PR-1 protein, a cytosolic ascorbate peroxidase protein and three resistance (R) gene proteins, in nineteen cultivars. All of the selected genes were analyzed using real-time PCR. The relative expression levels of the R-genes varied between cultivars. The basic PR-1 protein decreased expression in the majority of the cultivars, suggesting no involvement in the first twenty-four hours. Cytosolic ascorbate peroxidase relative expression levels suggest an increase in susceptible cultivars and a decrease in tolerant cultivars."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Cucurbit Downy Mildew (Pseudoperonospora cubensis): Cucumber Resistance"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Rideout, Steven L."],"dc:contributor.committeemember":["Donofrio, Nicole M.","Baudoin, Antonius B."],"dc:contributor.department":["Plant Pathology, Physiology, and Weed Science"],"dc:creator":["Cooper, Jessica G."],"dc:date.accessioned":["2014-07-18T17:32:32Z"],"dc:date.available":["2014-07-18T17:32:32Z"],"dc:date.issued":["2013-01-23"],"dc:description.abstract":["Pseudoperonospora cubensis (Bert. et Curt) Rost. is the causal agent of cucurbit downy mildew (CDM). It is the most damaging cucumber pathogen on the Eastern Shore of Virginia and eastern parts of the United States. Pseudoperonospora cubensis is an obligate oomycete pathogen, infecting crops within the Cucurbitaceae family. The disease is characterized by angular chlorotic lesions and a downy or felt-like appearance on the abaxial side of the leaf. Control of this pathogen includes use of resistant cucumber cultivars and costly fungicide programs. Continuous use has led to resistance to commonly used fungicides. This has become a major concern and in response, seed companies have developed cucumber cultivars which claim downy mildew resistance. This study evaluates different cucumber cultivars and assesses their level of resistance to CDM. The results indicate that an integrated management approach of reduced fungicide application and the use of resistant cultivars can suppress levels of CDM and yield a cucumber crop. Additionally, a molecular study was conducted, comparing the relative expression of genes encoding a basic PR-1 protein, a cytosolic ascorbate peroxidase protein and three resistance (R) gene proteins, in nineteen cultivars. All of the selected genes were analyzed using real-time PCR. The relative expression levels of the R-genes varied between cultivars. The basic PR-1 protein decreased expression in the majority of the cultivars, suggesting no involvement in the first twenty-four hours. Cytosolic ascorbate peroxidase relative expression levels suggest an increase in susceptible cultivars and a decrease in tolerant cultivars."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:114"],"dc:identifier.uri":["http://hdl.handle.net/10919/49606"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["cucurbit downy mildew","cucumber","CSA 06724","cyazofamid","fluopicolide","PR-1","cytosolic ascorbate peroxidase","CSA06758","CSA06757"],"dc:title":["Cucurbit Downy Mildew (Pseudoperonospora cubensis): Cucumber Resistance"],"dc:type":["Thesis"],"thesis:degree_discipline":["Plant Pathology, Physiology, and Weed Science"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:20:41Z"}