CGN tomato collection
The collection
In short- Support for breeding activities
- Maintaining genetic diversity
- Part of the fruit vegetables collection
In 1999, the original name Solanum lycopersicum (Heiser and Anderson 1999) was reintroduced. Rick (1976) had proposed earlier to divide the genus Lycopersicon into two subgenera, the ‘lycopersicum complex’ and the ‘peruvianum complex’ (Taylor and Al-Kummer 1982; Heuvelink 2004).
The ‘lycopersicumcomplex’ consists of the sixSolanumspeciesS. lycopersicum, S. pimpinellifolium,S. cheesmaniae,S. neorickii,S. chmielewskii, S. habrochaites andS.pennellii, that can be “easily” crossed with cultivated tomato.S. peruvianumandS. chilense, which have low ability to cross withSolanum lycopersicum, belong to the latter complex.
History
The history of the tomato collection is analog to the other CGN collections of pepper, eggplant, cucumber and melon and described in the general page of the fruit vegetables.
Composition
The collection includes about 1400 accessions and consists mainly of cultivars. The largest part of the collection is formed by the cultivated species Solanum lycopersicum. Most varieties come from Europe, USA and Canada and Russia. The landraces originate from countries all over the world. The wild species originate mainly from Peru and Ecuador.
Maintenance
To be incorporated in the collection, accessions need to have a minimum seed viability of 80% for cultivated material and 60% for accessions of wild species. Regeneration is carried out when seed viability is too low or when the remaining seed quantity has dropped below 1.0 g.
Regeneration/multiplication takes place in insect-free glasshouses on a substrate system where the stems are grown along ropes. Seven plants are used to regenerate self-fertilising tomato. Exceptions are heterogeneous accessions and outcrossing species like S. peruvianum of which at least 10 plants per accession are hand pollinated with a mixture of pollen. When samples are heterogeneous, ten plants are used.
Breeding companies, organized in Plantum NL, assist in the regeneration of tomato. Some accessions which are difficult to regenerate are put in isolation cages with bumble bees for pollination. During the growing season plants are monitored by the Dutch Plant Health Service for seed borne diseases in order to prevent seed contamination. Special attention is given to visual checks and leaf tests for the presence of seed-borne viruses and bacteria (e.g. Tomato Brown Rugose Fruit Virus (ToBRFV), Clavibacter michiganensis spp. michiganensis, Xanthomonas campestris pv. vesicatoria and Pepino Mosaic Virus (PepMV).
Characterisation
Characterization of fruit vegetables takes place during regeneration. Almost all accessions have been morphologically described. Until 2006 about 30 descriptors were used for each crop. Since 2006 the fruit vegetables are characterized by minimum descriptors developed by the ECPGR Working Groups. The minimum descriptor lists consist of about ten descriptors per crop and can be found at the ECPGR Solanacaeae webpage. All characterization data are made available on-line and in downloadable files.
The collections are well photo-documented, many pictures of (un)ripe fruits, plant and flowers are available. When necessary new pictures will be taken during regeneration and added to the CGN website.
Evaluation
Substantial parts of the tomato collection were screened for resistance to Tobacco Mosaic Virus (TMV), Pepino Mosaic Virus, Leaf mould (Cladosporium fulvum), Fusarium wilt (Fusarium oxysporum), Late blight (Phytophthora infestans), Didymella stem rot (Didymella lycopersici), Powdery mildew (Oidium lycopersicum) and Bacterial canker (Clavibacter michiganense subsp. michiganensis).
Regeneration of tomato
Seed dormancy
Fresh seeds may germinate irregularly. After storing the seeds for about half a year, the germination becomes normal.
Vernalization
None.
Sowing
Before sowing seeds are disinfected (see pepper), to avoid infection with Tobacco Mosaic Virus (TMV), and other viruses. Seeds are sown in seed trays at 23°C, generally between January and March, but it is possible to sow until July. After 10-14 days the seedlings are transplanted to rockwool blocks (12x12 cm) at a temperature of 23/20°C day/night.
Planting
About 7 weeks after sowing the plants in the Rockwool blocks are placed on Rockwool bags at a distance of 50 cm in the row and alternating 60 and 100 cm between the rows, at a temperature of 23/20°C day/night. The plants are grown along wires (1 stem per plant for the indeterminate types). Plants are pruned regularly, taking precautions to prevent virus transmission. During regeneration, plants are tested twice for occurrence of Pepino Mosaic Virus. About 2.5 months after sowing, the plants start to flower. To improve seed set the racemes are touched with a vibrator, improving the pollination.
Per accession seven plants are used for regeneration. For cross-pollinating wild species or heterogeneous accessions up to 14 plants are used. For these species a pollen-mixture of all plants in the accession is used for hand pollination.
Harvesting
About 5 months after sowing, the fruits start to ripen. Per plant, 10 or more ripe fruits are harvested.
Pest and disease control
Biological control
- Spider mites with Phytoseiulus persimilis
- Thrips with Phytoseiulus persimilis and Orius laevigatus
- Whitefly with Aphidius colemani
- Aphids with Encarsia formosa
Pesticide treatments
Non-preventive:
- Spider mites, in case biological control is not effective.
During regeneration the plants are checked visually for diseases by the Netherlands Inspection Service for Horticulture (Naktuinbouw). In case of doubt, the plants are tested to determine the disease. Infected plants are removed.
Gene bank for plant resources
View the database or submit a request for genetic material.
Do you have a question?
Do you have a question about the tomato collection? Ask our curator:
ing. W (Willem) van Dooijeweert
curator fruit vegetables
