Other Initiatives

Collaboration for Plant Pathogen Strain Identification (CPPSI)

The Collaboration for Plant Pathogen Strain Identification (CPPSI) is a U.S.-based initiative committed to standardizing the identification of plant pathogen strains or races and variety resistance determination. This is accomplished through distribution of validated host differentials and type isolates, also known as reference materials.

CPPSI’s mission has been bolstered by the continuous support of key industry and academic entities, including ISF, American Phytopathological Society (APS), and the American Seed Trade Association (ASTA). The UC Davis Seed Biotechnology Center serves as the operational headquarters for CPPSI, providing an innovative environment for seed science research.

An integral part of CPPSI’s mission is the dissemination of knowledge and resources. The CPPSI white papers, which detail the methodologies, findings, and insights, are readily accessible for public viewing. You can access them here (below) or alternatively at the CPPSI website.

CPPSI WHITE PAPERS:

Visit the CPPSI website for more information and to learn how you can contribute to our cause.

Access to available CPPSI reference materials is detailed in the white papers or can be found directly by searching “CPPSI” via the USDA’s Germplasm Resource Information Network (GRIN). Seed and isolates with CPPSI designations have been tested for the proper reactions by the CPPSI working group.

The European Seed Association (Euroseeds)

Company claims on the level of resistance in a variety to a pathogen are based on tests carried out with well-characterized isolates of the pathogen in controlled environmental conditions. This resistance may be effective against all or some biotypes, pathotypes, races or strains of the pathogen. However, pathogens are known to develop and form new biotypes, pathotypes, races or strains that can cause damage to plants that remain unaffected by the original form of the pathogen.

To provide support to companies in case of litigation through clear and consistent communication on disease resistance in vegetable crop varieties, Euroseed’s Working Group on Harmonization of Resistance Terminology has put together information on the strain/race of a pathogen to which commercial or other varieties are resistant and the level of resistance in a reference variety. This information is available for vegetable crops of the following types/categories – Brassicas/root crops, Cucurbits, large seeded crops, leafy crops and Solanaceae, and is updated regularly.

For more information see Euroseeds’ Harmonized Resistance Tables.

The International Bremia Evaluation Board (IBEB)

IBEB is a joint initiative of lettuce breeding companies in France and the Netherlands, the Dutch inspection service (Naktuinbouw) and the French National Seed Station (GEVES). IBEB aims to maintain and promote a well-defined and internationally agreed system of race denomination and to streamline the process of identifying new races of Bremia lactucae on the basis of annually updated information about the evolution of the pathogen in response to resistance in lettuce varieties. Companies provide information on the genetic background of varieties while Naktuinbouw and GEVES serve as independent testing facilities.

More information about IBEB on this page.

Press Release (1 June 2021): “Bremia lactucae, Bl: 37EU identified and denominated in Europe”

INIA – Seeds and Nursery Plants Testing Station

Plant Health Laboratory main activity:

We carry out pathogen resistance tests on vegetable varieties, in accordance with CPVO (Community Office of Vegetables Varieties) and UPOV (International Union for the obtaining of new commercial plant varieties) protocols wich complement the technical study carried out at the Valencia Center for Variety Evaluation Tests. These tests are necessary for the granting of plant breeders´s rights at national and European level and/or the authorisation of the marketing of new plant varieties.

Services and analytic techinics:

Pathogen collection maintenance and update. The collection include viruses, bacteria, fungi and nematodes for own use and supply to companies in the sector. We are also members of the Harmorescoll European Network.
Pathogen detection tests in seeds lots following ISTA (International Seed Testing Association) and ISF (International Seed Federation) protocols for monitoring seed health status.
Pathogens resistance tests in horticultural varieties, mainly in tomato, pepper, lettuce, CUCUMBER, BEAN, PEA AND melon.
Supply of inoculates to companies or organizations.
Development of pathogen resistance protocols.

Collaboration and participation

Collaboraiton with companies in the SEED sector: INIA-ANOVE (National Associtation of Plant Breeders) agreement on the conduct of research in the field of seed health
Collaboration with EU examination offices in charge of DUS test
Participation in training courses: “Plant Variety Rights online technical training for experts”
Participation in international plant health groups, including participation in the ISF 2021 Disease Resistance Terminology Working Group
“Harmonization of resistance test to diseases of vegetable crops in the European Union” Project, financed by the OCVV
“Harmorescoll: Setting up an EU System for harmonized collections of reference isolates, controls and differentials to facilitate disease resistance testing” Project, financed by the OCVV
Participation in the development and review of CPVO and UPOV protocols

More Information about INIA on this webpage: www.inia.es

The International Working Group on Peronospora effusa (IWGP)

IWGP was set up through the Dutch seed association Plantum NL by Naktuinbouw and companies trading spinach seed. It is supported by research centres in the USA, including the University of Arkansas and the University of California Cooperative Extension. IWGP continuously monitors the development of new races of downy mildew on spinach globally by testing uncommon field isolates on a fixed, common host differential set of varieties that contain the full range of available resistances, and denominate new races as and when necessary. IWGP aims to promote a consistent and clear communication between the seed industry, growers, and other interested parties about all resistance-breaking races that are persistent enough to survive over several years, occur in a wide area, and cause a significant economic impact.

For the latest updates type ‘spinach’ or ‘IWGP’ in the search area of Naktuinbouw’s News Overview.

Two new races of the downy mildew pathogen (Peronospora effusa) on spinach have been denominated by the International Working Group on Peronospora in spinach (IWGP) on the basis of a worldwide evaluation of isolates from growers fields and trap nurseries. The virulence patterns of all races are published as reference data by the International Seed Federation (ISF). For further information see the press release (15 April 2021) here.

Resistance tests at GEVES

The evaluation of the resistance of varieties to pests and diseases is very important for varietal innovation, as it will provide a better description of the varieties being studied for registration in the National Catalogue and also for plant breeders’ rights. It necessitates the use of protocols, which are representative of the in-field reality, thus giving consistently reliable results with regard to the epidemiological situations that the registered varieties will confront.

Among its official missions, GEVES, the French Variety and Seed Study and Control Group, is responsible for:

Registration of new plant varieties in the official Catalogue
Legal protection of varieties (plant variety rights)

It is possible for GEVES to achieve this at a European level through the implementation of harmonization programmes for DUS protocols (CPVO technical protocols and UPOV technical guidelines), by using validated and harmonized reference materials, and through the collaboration of Research Institutes in the epidemiological monitoring of strains.

More information about disease resistance testing is available on the GEVES website

MATREF

MATREF is a network of reference material managed by GEVES for testing varieties for resistance to pathogens and pests. It was created in 2002 for disease resistance tests performed for registration in the official French catalogue (CTPS), for Plant Variety Rights (CPVO or INOV), or for external clients.

In 2025, MATREF includes 220 control varieties and differential hosts, as well as 68 pathogens and pests (in connection with ISF differential host sets).

MATREF’s objectives are to:

Provide reliable and available reference material for disease resistance tests, including:
- Controls: susceptible, intermediate, resistant cultivars
- Differential hosts: for identification of races
- Pest and pathogen isolates
Harmonise reference material (controls, differential hosts, pathogens and pests) between official laboratories and seed companies in order to optimise the consistency of results for resistance assessment when GEVES and INRAE check the resistance claims of seed companies.
Share tasks and costs between network members for validation, maintenance, and distribution of seed and pathogen strains.

The network is composed by private seeds companies and public partners (GEVES and INRAE).

For more information, please see: MATREF on the GEVES website

The Naktuinbouw-Plantum Isolate Collection

The Plantum Isolate Collection at Naktuinbouw is an initiative of Naktuinbouw and Plantum. Naktuinbouw is the Dutch examination office for plant varieties; Plantum is the Dutch trade association for companies in breeding, propagation and cultivation of seeds and young plants. The isolates in this are used for resistance evaluation of plant varieties of vegetable crops. They are maintained by breeding companies and validated regularly through biotests on susceptible and resistant varieties. Members and Non-members of the collection can order isolates for use as reference isolates in resistance testing. Plant virus, bacterium, fungus, nematode and aphid isolates have been included in the collection. The complete list of isolates can be found at the Naktuinbouw website.

Disease resistance testing at Naktuinbouw

Reliable information about disease resistances is important for growers, allowing them to maintain crop health without negative side-effects. Commercial disease resistance claims from breeders become more trustworthy after independent confirmation in highly reproducible official tests. These official tests are serving the common and diverse interests of breeders, growers and consumers.

Naktuinbouw is authorized for official variety testing, including many important resistance characteristics. Some of these are obligatory for the variety description that is needed for listing and subsequent commercialisation of the variety or for the application for Plant Breeders’ Rights. Naktuinbouw collaborates with breeders and other registration authorities on harmonization of the test procedures, isolates and standard varieties in official disease resistance tests.

If necessary, Naktuinbouw participates in monitoring and defining resistance-breaking isolates in a practical, collaborative, and scientifically valid way, and plays a key role in promoting the worldwide use of race-defining differentials for the downy mildews in spinach and lettuce, and for clubroot in cabbage.

Official disease resistance testing protocols are published by the European Community Plant Variety Office (CPVO). Resistance tests that follow the CPVO protocol are performed by Naktuinbouw not only for internal requests for official variety descriptions, but also for external requests from breeders or other parties. More detailed information about disease resistance testing can be found on the Naktuinbouw website.

Project Harmorescoll towards a European platform to improve resistance testing for DUS

Harmorescoll aims to improve the availability of reference materials in DUS resistance tests. The project (2020-2024) was co-funded by CPVO and led by GEVES and Naktuinbouw, with members of other European examination offices and the seed industry. It gave rise to the establishment of lists of seed varieties and pest isolates described in the CPVO protocols and UPOV guidelines that have been validated as references, based on a set of rules defined within the project. Contact initiatives have also been defined to access these reference materials. The future organization of the Harmorescoll network is currently under discussion to ensure that the validated materials become and remain available for DUS testing. All information will be available on a dedicated website (not yet publicly launched).