Disease resistance testing at Naktuinbouw
Resistance to pests and diseases is important to maintain crop health. Growers need reliable information about resistances when they have to choose a variety. Naktuinbouw promotes the use of reliable information about resistance through testing for internal use, offering tests to clients and by collaborating with breeders and other registration authorities.
Naktuinbouw runs different types of tests and keeps isolates and seeds of differential sets.
1. Resistance tests for official variety descriptions
2. Resistance tests for external clients
4. Isolate collection and delivery service
5. Differential set delivery service
1. Resistance tests for official variety descriptions
For some vegetable crops, information about resistance must be included in the variety description that is required to define and protect a variety. Naktuinbouw can run resistance tests at least once a year for these so-called obligatory disease resistance characteristics.
Companies often want to include not only the obligatory resistance claims in the official variety description. This is possible if the company protocol conforms to an official protocol published by CPVO. Naktuinbouw must be able to check the company’s resistance claims if the variety is to be protected by Plant Breeders’ Rights or if the variety is to be listed. Naktuinbouw therefore can also test these non-obligatory disease resistance characteristics.
2. Resistance tests for clients
Parallel to the resistance tests for the official variety descriptions, Naktuinbouw also offers disease resistance tests as a service to clients. The same official testing protocol will be used. Tariffs are stated here.
A sample of 100 seeds is required for each resistance test as this means that the test can be repeated without any delay if the test fails.
Most resistance test requests can be handled within 6 months; some will take one year. If the test is urgent, Naktuinbouw will always try to adapt its planning.
3. Isolate determinations
Individual isolates of the same pathogen may be able to overcome specific resistances. It is therefore useful to define races based on their reaction to a range of well-characterised differential varieties. Naktuinbouw offers a pathotest on the lettuce differentials for defining Bremia lactucae races and on spinach differentials for defining Peronospora farinosa f. sp. spinaciae races. Tariffs are stated here.
We can also determine the race identity of Fusarium oxysporum f.sp. lycopersici. The price of this and other pathotests is available on request; please, send an e-mail.
4. Isolate collection and delivery service
Naktuinbouw has an isolate collection with 70 isolates of plant pathogens. The collection covers viruses, bacteria, fungi, and nematodes and is used for resistance testing in connection with variety registration trials in vegetable crops. The isolates are validated regularly through biotests on susceptible and, if possible, also on race-differentiating resistant varieties.
The isolate collection is an initiative of Naktuinbouw in collaboration with 10 Dutch vegetable seed companies. All are members of Plantum, the Dutch association for breeding, tissue culture and trade of seeds and young plants. The 8 companies are (in alphabetical order): Bejo Seeds, Enza Zaden, Monsanto Holland, Nickerson Zwaan, Nunhems, Pop Vriend Seeds, Rijk Zwaan and Syngenta Seeds. They support the initiative financially through an annual contribution, covering the costs of maintaining and validating the isolates. The companies are represented in a working group. This also acts as a platform that organises an annual workshop to improve communication about common resistance testing problems, and strengthens the variety registration system using expert knowledge.
Non-members can also use the Naktuinbouw isolate collection as a reference for resistance testing. For non-members, the number of isolate deliveries per year is limited. Contribution fees are mentioned in the current price list. For members, the number of isolate deliveries is unlimited and free of charge.
For most isolates, the delivery time will be one week. You can place an order by sending an e-mail, also for questions on other isolates. The amount of inoculum is enough for multiplication, but not for immediate resistance testing. For fresh material of obligate parasites like Bremia lactucae and Peronospora farinosa f. sp. spinaciae the delivery time may vary between one month and one year. Additional costs may apply for handling and delivery.
5. Differential set delivery service
For Bremia lactucae and Peronospora farinosa f. sp. spinaciae, Naktuinbouw is also distributing seeds of a set of differentials varieties, needed for specific pathogen race determination. The lettuce or spinach differentials are distributed free to every organisation with an interest in and commitment to the harmonisation of resistance tests or monitoring the development of these pathogens. The maintenance of the differential sets is the result of a collaborative effort of seed companies in the IBEB (International Bremia Evaluation Board) and the IWGP (International Working Group on Peronospora in spinach).
