The collection composition
Capsicum species in the CGN collection are diploid and have 24 chromosomes. The part of the Genus Capsicum which is used for cultivation and breeding, can be divided in three complexes:
- annuum complex (C. annuum, C. chinense, C. frutescens, C. galapagoense)
- baccatum complex (C. baccatum, C. praetermissum, C.tovarii)
- pubescens complex (C. pubescens , C. cardenasii, C. eximium)
Lately more species have been described under which species with 2n=26.
Currently (March 2012) the collection includes 1011 accessions and is the fourth largest of Europe. The cultivated species, Capsicum annuum, C.chinense, C.frutescens, C.baccatum en C. pubescens and a number of crop wild relatives are represented.
The collection comprises of 501 cultivars, 227 landraces, 22 research material, 56 accessions of wild species and 205 samples of unknown population type. C. annuum (783 accessions) forms the largest part of the collection followed by C. chinense (116) and C. frutescens (45). Most varieties originate from Europe and the USA. About 25% of the landraces come from Brazil. It appears that in Europe not many accessions of wild species are represented in ex-situ genebanks. The same situation occurs at CGN but from most countries of South America a few accessions of wild species are included.
Parts of the pepper collection are evaluated for resistance to different strains of Tobamo viruses, Tomato Spotted Wilt Virus (TSWV), Anthracnose (Colletotrichum capsici) and preference of California Thrips (Frankiniella occidentalis), the transmitter of TSWV.
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 to low or when the remaining seed quantity has dropped below 2.5 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 pepper. Exceptions are heterogeneous accessions and outcrossing species like C. cardenasii of which at least 10 plants per accession are hand pollinated with a mixture of pollen. When samples are heterogeneous, fourteen plants are used.
The Dutch breeding companies assist in the regeneration of pepper. 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.
Regenerations are carried out in close cooperation with breeding companies which are member of the Dutch Association for the Plant Reproduction Material Sector (Plantum NL).
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.
Genetic analyses with AFLP, RAPD and ISSR marker systems were used to determine genetic variation and phylogenetic relationships within Capsicum annuum (Kochieva et al.), C. frutescens, C. chinense and C. baccatum (Rhyzhova et al., 2008). Results have been used in rationalising the collection.