I.W. Boukema

Reduction of duplication in a Brassica oleracea germplasm collection

SummaryTo reduce the number of accessions in the Brassica oleracea collection of the Centre for Genetic Resources The Netherlands (CGN) groups of accessions were bulked. Accessions in a group were selections from the same landrace or old variety, and were chosen, with the help of crop experts, on the basis of their history and morphology. Since this approach was received rather sceptically in the genebank community, a genetical analysis of some of the groups and their components (named varieties) was made to justify the procedures. A selection of white cabbage and Brussels sprouts, representing two crop types of B. oleracea, was made: eleven white cabbage groups comprising 43 components, and nine Brussels sprouts groups comprising 24 components. Each group and all of its components were described on the basis of electrophoresis of nine isoenzymes on 30 plants. Most components were rightly classified; 16 percent were misclassified. All these misclassifications were within similar groups. It could be concluded that pooling of the components included in this study was justified. In two cases the isozymic patterns suggested that the groups could even have been larger. Only in the case of the two groups of Brussels sprouts ‘Bedfordshire’ this was a real option. In the other case involving the white cabbage groups ‘Langedijker Bewaar Gewoon’, ‘Langedijker Bewaar Graag’ and ‘Late Herfstdeen’ this was not an option since these landraces, although having a common genetic background, clearly have a distinct identity as defined by morphology and history.

Broadening the genetic base of onion to develop better-adapted varieties for organic farming systems

SummaryAs organic farming refrains from high and chemical inputs it needs varieties better adapted to organic conditions to improve the yield stability and quality of crops. In order to make genebank accessions more accessible for the utilisation in organic breeding programmes, a participatory research project with farmers was carried out in 2002 and 2003. From the Dutch genebank collection 37 onion accessions, divided into five different groups (according to their market use), were selected and planted at a commercial organic farm. Farmer participation in characterisation and evaluation of the material resulted in including additional plant traits for genebank characterisation as well as new selection criteria for breeding. It also provided researchers insight into how organic farmers evaluate and value certain plant traits. Variation for important properties was found within and between the five groups. To establish base populations, the farmers, in collaboration with the researchers, selected the best genotypes within the five groups of onion accessions. The new base populations may be exploited in order to achieve better-adapted material for organic farming systems.

Marker-assisted reduction of redundancy in a genebank collection of cultivated lettuce

To reduce the level of redundancy in a collection of cultivated lettuce, data from 160 amplified fragment length polymorphism (AFLP) fragments and 10 polymorphic microsatellites were used in combination with passport data and morphological data, the latter obtained from an experimental field trial performed for verification purposes. Based on the observed distribution of the number of marker differences between and within accessions, a minimum of three AFLP differences and two microsatellite differences were regarded as levels warranting distinction between accessions in the redundancy analysis. The strategy followed in the redundancy analysis was mainly based on the confirmation of duplication by each of two independently generated data sources. The molecular data were used for the validation as well as the identification of potential duplicates, revealing a total number of 198 redundancies, corresponding to 12.9% of the total collection. Trueness to type, number of characterization and evaluation data, and collection management considerations, such as available seed quantities and germination percentages, were used as primary, secondary and tertiary criteria to decide which accession from duplication groups to maintain in the collection. Removal of accessions showed negligible effects on total collection diversity, as quantified for AFLPs and microsatellites, characterization and evaluation traits and resistance profiles against downy mildew pathotypes, indicating that the applied strategy was effective.

14 Genetic resources

Publisher Summary This chapter discusses the genetic resources. Although the numbers given might be overestimated, high numbers of Brassica accessions are conserved in collections all over the world. Regeneration of Brassica is very costly. Therefore, good storage conditions, to maintain the seed viability, are essential. It is also important to avoid unnecessary duplicates. Consequently good and accessible information on the material in the collections is needed to trace these duplicates. For the wild Brassica species, in situ conservation is of high importance; the ex situ collections help to make a small part of the diversity readily accessible for utilization. To guarantee availability of Brassica germplasm to future generations, funding agencies, such as national governments, need to commit themselves to support coherent conservation programs. These should comprise of ex situ strategies for the conservation of cultivated material, and in situ strategies, for the wild material. Gene banks and the other entities involved in the conservation of Brassica have to coordinate their activities better, to avoid and reduce unnecessary duplication of efforts and set targeted priorities.