FEBRUARY 2018 SEEDWORLD.COM / 11 CONSISTENT NAMING OF plant pathogen strains and races is a recognized need in the vegetable seed industry. Until very recently there has been no recognized global body that regulates the naming of plant pathogen strains. In 2007, a U.S. based effort was initiated by the International Seed Federation (ISF) in partnership with the American Phytopathological Society (APS) to address this issue with a focus on disease systems for which claims of disease resistance are made by the seed industry. In 2013, the effort took the name of the Collaboration for Plant Pathogen Strain Identification (CPPSI). CPPSI is a science based, vegetable seed industry initiative developed to standardize the identification of plant pathogen strains and races. Each pathogen’s identification is based on a set of host differentials, each containing a source of disease resistance and reference plant pathogen strains, collectively referred to as Reference Materials. Since early 2015, CPPSI has been based at the U C Davis Seed Biotechnology Center. A three-year commitment of fund- ing from seven seed industry founding sponsors – Bayer Crop Science, Enza Zaden, HM.Clause, Monsanto, Rijk Zwaan, Sakata and Syngenta Seeds – provided the initial support for this initia- tive. These same sponsoring members continue to support the CPPSI initiative. In 2017, CPPSI was awarded a California Department of Food and Ag Specialty Crop Block Grant. These funds will facilitate the continued growth of this initiative. Addressing an Ongoing Problem “Gaps and inconsistencies in plant pathogen strain naming and identification are an ongoing seed industry issue that can under- mine published claims of disease resistance,” says Phyllis Himmel, Ph.D., CPPSI director. “For example, claims of resistance to melon and tomato Fusarium wilt in the U.S. might be made against strains 1, 2 and 3, but in Europe, claims against these same strains are made as 0, I and 2. Because we have followed different strain naming guide- lines, vegetable seed catalogues in the U.S. and Europe must list claims made in both regions. CPPSI is collaborating with associa- tions and organizations in Europe to bring uniformity and consist- ency to the naming of plant pathogen strains in disease systems as new differentiating hosts are developed,” Himmel says. Without a variety registration system in the U.S. there has not been as much attention paid to consistent naming of pathogen strains. The same strain could have different names or differ- ent strains could be given the same name. These inconsisten- cies can become a problem for international seed companies wanting to register new varieties in Europe. To register a new variety, a breeder must be able to show the new variety is dis- tinctive, unique and stable (DUS). The resistant and susceptible responses to designated plant pathogens is part of the criteria. The listed claims for resistance may not match up with what the European registration board might expect to find when resist- ance is identified by strains with different names. “CPPSI’s effort to standardize plant pathogen strain naming and identification is important to the global seed industry,” says Staci A. Rosenberger, Applied Pathology Lead for North America at Monsanto Vegetable Seeds. “Using a standard refer- ence host-pathogen set serves as a basis for equivalency testing across regions and builds confidence and clarity in disease resist- ance claims not only for seed companies, registration authorities and academia, but also for seed dealers and growers.” Rosenberger says another critical function of CPPSI is to serve as a central repository for host differentials and pathogen collections which provide tremendous value when developing new detection methods for plant pathogens. “Monsanto supports CPPSI’s mission and recognizes the value that this effort brings to our customers,” Rosenberger says. Hub and Spoke System CPPSI’s Reference Materials enable pathologists to use a ‘common language’ when identifying new races/strains of a pathogen that has overcome commercially deployed resistance genes. These materials provide a reference for determining pathogen strain virulence. CPPSI working group members developed a double hub and spokes system for germplasm and pathogen strain storage and distribution. Information and resources from each hub is available to CPPSI members at no additional cost. Nonmembers also have access to CPPSI information and resources as a fee-based service. The USDA National Plant Germplasm System centers serve as a hub for deposit, storage and distributing of differentiating host sets. A network of public, private and USDA labs serve as the hub for cul- turing and distributing the reference plant pathogen strains. Linking the two hubs is www.cppsi.org. The Collaboration for Plant Pathogen Strain Identification (CPPSI) aims to regulate naming plant pathogen strains and races.Joe Funk jfunk@issuesink.com STANDARDIZING PLANT PATHOGEN IDENTIFICATION