Phytophthora ramorum Multilocus Genotyping Database

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About the Project

Phytophthora ramorum is considered to be an emerging pathogen that has received worldwide attention as the causal agent of Sudden Oak Death (SOD). This pathogen was simultaneously discovered in Europe on Rhododendron and Viburnum species (Werres et al., 2001) and in California on tanoak (Lithocarpus densiflorus) and coast live oak (Quercus agrifolia) (Rizzo et al., 2002). P. ramorum was formally described as a new species in 2001 (Werres et al., 2001). P. ramorum has received wide attention because (i) it has a large host range, (ii) causes severe mortality of tanoak and coast live oak in natural ecosystems, and (iii) affects many nursery hosts thus providing this pathogen a means of dispersal throughout the US. The host range currently includes over 41 plant species and continues to increase. Most importantly, nursery crops offer a very effective means of dispersing the pathogen across the country. This has happened twice with shipments of infected camellias from California that resulted in 1.6 million potentially infected plants detected in 175 infested sites in over 20 states (see APHIS SOD website). Once a nursery location is found to be infected with P. ramorum state and federal government agencies generally try to trace infection back to an infected nursery of origin, or, if shipments have been made, attempts to trace the infection forward to nursery or retail operations that received shipments from an infected site. This database provide timely information on distribution of genotypes found in North America that can facilitate dissection of migration pathways.


Populations of P. ramorum are currently being characterized using multilocus microsatellite genotyping following protocols developed by Ivors et al. (2006), Prospero et al. (2007), and Garnica et al.(2006). This searchable database provides timely information on new finds of isolates placed in one of three clonal lineages. The database is searchable with the pull-down fields at the top of the database page. Maintenance and changes to the database are password protected.


Major funding for this project is provided by grant 06-IA-045 awarded to NJ Grünwald and EM Hansen from the USFS PSW Sudden Oak Death call for proposals.


Garnica DP, Pinzon AM, Quesada-Ocampo LM, et al. (2006) Survey and analysis of microsatellites from transcript sequences in Phytophthora species: frequency, distribution, and potential as markers for the phylum Oomycota. BMC Genomics 7, 245.

Ivors K, Garbelotto M, Vries IDE, et al. (2006) Microsatellite markers identify three lineages of Phytophthora ramorum in US nurseries, yet single lineages in US forest and European nursery populations. Molecular Ecology 15, 1493-1505.

Prospero S, Hansen EM, Grünwald NJ, Winton LM (2007) Population structure of the sudden oak death pathogen Phytophthora ramorum in Oregon from 2001 to 2004. Molecular Ecology, in press.

Rizzo DM, Garbelotto M, Davidson JM, Slaughter GW, Koike ST (2002) Phytophthora ramorum as the cause of extensive mortality of Quercus spp. and Lithocarpus densiflorus in California. Plant Disease 86, 205-214

Werres S, Marwitz R, Veld W, et al. (2001) Phytophthora ramorum sp. nov., a new pathogen on Rhododendron and Viburnum. Mycological Research 105, 1155-1165.

For questions or to suggest improvements, please e-mail grunwaln <at>

Last Updated:  June 26, 2007