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
 Horticultural Crops Research Unit: Corvallis, OR
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    Other
                        History
                                    Useful Links
                    HortHappenings News PageSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Corvallis, Oregon Horticultural Crops Research Unit 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
                                            PROSPERO, S - UMR BIOGECOitem
                                            HANSEN, E - OREGON STATE UNIVERSITYitem
                                            Grunwald, Niklaus

                                                         - *Nik*item
                                            Winton, Loretta
  Submitted to: Molecular Ecology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 4/17/2007
                                    Publication  Date: 7/6/2007
                                    Citation: Prospero, S., Hansen, E.M., Grunwald, N.J., Winton, L.M. 2007. Population dynamics of the sudden oak death pathogen Phytophthora ramorum in Oregon from 2001 to 2004. Molecular Ecology. 16:2958-2973.Interpretive Summary: Phytophthora ramorum is an emerging plant pathogen in Curry County forests in southwestern Oregon. Moreover, since 2003 it has been repeatedly isolated from plants in Oregon nurseries. In this, study we analyzed the genetic diversity of the population of this pathogen in Oregon from 2001 to 2004 by using microsatellites. Microsatellites are a common molecular tool used to characterize the genetic diversity and structure of populations of any organism. A total of 323 isolates (272 from the infested forest and 51 from nurseries) were screened at 10 microsatellite loci. Twenty-four multilocus genotypes were identified from the forest. Genotypic diversities were low among the 2001 to 2004 forest populations. In contrast, the nursery population was composed of 11 genotypes. No dominant genotype was observed and only two nursery genotypes were also found in the forest. Significant differentiation, showing that clear differences in the genetic structure of populations, was detected between nursery and forest populations. One nursery genotype belonged to the European lineage of P. ramorum. No evidence of sexual recombination between isolates belonging to the European (A1 mating type) or North American (A2 mating type) clonal lineages was observed. All A2 isolates screened belonged to the same clonal lineage. The low population diversity of P. ramorum in southwestern Oregon supports the hypothesis that this pathogen is not native to Oregon. The nursery infestation is not caused by the genotypes observed in Curry County, but likely resulted through introduction of novel genotypes from nurseries located outside Oregon. This highlights the continued importance of sanitation and quarantine in nurseries to prevent further introduction and spread of P. ramorum.
                                Technical Abstract: Phytophthora ramorum (Oomycetes) is an emerging plant pathogen in forests in southwestern Oregon (Curry County). Moreover, since 2003 it has been repeatedly isolated from plants in Oregon nurseries. In this study, we analyzed the genetic diversity of the P. ramorum population in Oregon from 2001 to 2004 by using microsatellites. A total of 323 isolates (272 from the infested forest and 51 from nurseries) were screened at 10 microsatellite loci. Twenty-four multilocus genotypes were identified from the forest. In all sampling years, 60-70% of the isolates belonged to the same genotype. Genotypic and gene diversities were low and no significant differentiation was detected among the 2001 to 2004 populations. The nursery population was composed of 11 genotypes. No dominant genotype was observed and only two nursery genotypes were also found in the forest. Significant differentiation was detected between nursery and forest populations. One nursery genotype belonged to the European lineage of P. ramorum. No evidence of sexual recombination between isolates belonging to the European (A1 mating type) or North American (A2 mating type) clonal lineages was observed. All A2 isolates screened belonged to the same clonal lineage. The low population diversity of P. ramorum in southwestern Oregon supports the hypothesis that this pathogen is not native to Oregon. The nursery infestation is not caused by the genotypes observed in Curry County, but likely resulted through introduction of novel genotypes from nurseries located outside Oregon. This highlights the continued importance of sanitation and quarantine in nurseries to prevent further introduction and spread of P. ramorum.


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