U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Northeast Area Geneva, New York Grape Genetics Research Unit (GGRU) Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Cadle-Davidson, Lance
  Submitted to: Plant Disease
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 10/21/2008
                                    Publication  Date: 11/15/2008
                                    Citation: Cadle Davidson, L.E. 2008. Variation within and between Vitis species for foliar resistance to the downy mildew pathogen Plasmopara viticola. Plant Disease. 92:1577-1584.Interpretive Summary: To complement existing control strategies, grape growers in humid climates desire cultivars with resistance to downy mildew, caused by Plasmopara viticola. Numerous disease resistance screens of diverse Vitis germplasm have previously been conducted to identify downy mildew resistance, but ratings of named cultivars were inconsistent and identities of resistant individuals in wild species were not typically provided. Because inconsistencies between studies could be due to differences in pathogen genetics, we used controlled inoculations of a single pathogen isolate onto two leaf ages of 883 Vitis accessions and compared these results to natural infection in a five-fold replicated vineyard of 80 Vitis accessions in 2006 and 2007.  The analysis of results highlights important factors for downy mildew resistance screens: leaf age, pathogen genotype(s), and host species and genotype. The results further underscore the importance to breeders of uniform testing in multiple environments.
                                Technical Abstract: To complement existing control strategies, grape growers in humid climates desire cultivars with resistance to downy mildew, caused by Plasmopara viticola. Numerous disease resistance screens of diverse Vitis germplasm have previously been conducted to identify downy mildew resistance, but ratings of named cultivars were inconsistent and identities of resistant individuals in wild species were not typically provided. Because inconsistencies between studies could be due to differences in pathogen genetics, we used controlled inoculations of a single pathogen isolate onto two leaf ages of 883 Vitis accessions and compared these results to natural infection in a five-fold replicated vineyard of 80 Vitis accessions in 2006 and 2007. Of the accessions rated in both assays, 16.2% were resistant to a single isolate but susceptible in the vineyard. Otherwise, there was a good correlation of ratings between the field assay and the rating of older leaves (r=0.62-0.71). Five accessions from V. cinerea, V. labrusca, and V. x champinii averaged zero severity in both vineyard years, yet some individuals of V. cinerea and V. labrusca were moderatley or highly susceptible in the field. Similarly, although significant differences in mean severity separated V. vinifera, V. hybrid, V. riparia, and V. labrusca for single isolate inoculations (from susceptible to resistant) notable within species variation was identified for all well-represented species. Resistant individuals were identified in most species with the prominent exceptions of V. vinifera and V. acerifolia. Single-isolate resistance ratings in 2006 corresponded well (94.6%) to 2007 ratings using a separate isolate collected from the same vineyard. Categorizing the ratings for this and previous studies, ratings infrequently corresponded among previous studies (31.9%) as well as between previous studies and single-isolate (34.9%) or vineyard (46.4%) ratings. These results highlight important factors for downy mildew resistance screens: leaf age, pathogen genotype(s), and host species and genotype. The results further underscore the importance to breeders of uniform testing in multiple environments.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov