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A Global Marker Database for Phytophthora infestans

July 1998 , Volume 82 , Number  7
Pages  811 - 818

Gregory A. Forbes , International Potato Center (CIP) ; Stephen B. Goodwin , USDA-ARS, Department of Botany and Plant Pathology, 1155 Lilly Hall, Purdue University, West Lafayette, IN 47907 ; André Drenth , CRC for Tropical Plant Pathology, The University of Queensland, Brisbane 4072, Australia ; Pedro Oyarzun and Maria Eugenia Ordoñez , International Potato Center (CIP), P.O. Box 17-21-1977, Quito, Ecuador ; and William E. Fry , Department of Plant Pathology, 334 Plant Science, Cornell University, Ithaca, NY 14853

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Accepted for publication 9 April 1998.

A marker database was compiled for isolates of the potato and tomato late blight pathogen, Phytophthora infestans, originating from 41 locations which include 31 countries plus 10 regions within Mexico. Presently, the database contains information on 1,776 isolates for one or more of the following markers: restriction fragment length polymorphism (RFLP) “fingerprint” consisting of 23 bands; mating type; dilocus allozyme genotype; mitochondrial DNA haplotype; sensitivity to the fungicide metalaxyl; and virulence. In the database, 305 entries have unique RFLP fingerprints and 258 entries have unique multilocus genotypes based on RFLP fingerprint, dilocus allozyme genotype, and mating type. A nomenclature is described for naming multilocus genotypes based on the International Organization for Standardization (ISO) two-letter country code and a unique number. Forty-two previously published multilocus genotypes are represented in the database with references to publications. As a result of compilation of the database, seven new genotypes were identified and named. Cluster analysis of genotypes from clonally propagated populations worldwide generally confirmed a previously published classification of “old” and “new” genotypes. Genotypes from geographically distant countries were frequently clustered, and several old and new genotypes were found in two or more distant countries. The cluster analysis also demonstrated that A2 genotypes from Argentina differed from all others. The database is available via the Internet, and thus can serve as a resource for Phytophthora workers worldwide.

Additional keywords: DNA fingerprints, population genetics, RG57

© 1998 The American Phytopathological Society