Schriften zu Genetischen Ressourcen - Genres

L. FRESE
undertaken to estimate the genetic similarity between accessions within a group of
probable duplicates. The preliminary results indicate that there are less duplicates
than expected. The results also indicate a curator’s decision problem. There are, for
example, entries in the duplicate group “Lucullus” (most original sample IDBB2629)
that are similar at a 90% level (entry 133 and 134) while others (entry 140) are rather
distinct (Fig. 1) (FORD-LLOYD 2000, FORD-LLOYD et al. 2001).
Whether entry 134 can be considered as redundant material that should be combined
with 133 under the assumption that both accessions contain the same useful
genetic variation still is at the curator’s discretion.
To avoid unintentional screening of duplicates, a core collection of the “most original
accessions” has been created using taxonomic and geographic data documented in
the IDBB as well as curator’s knowledge (FRESE 2000). Between 600 and 800 accessions
of this core collection have been screened for resistance to eight diseases as
well as for drought tolerance. The data set emerging from the EU project GENRES
CT95-42, including AFLP and SSR data derived from the duplicate search subproject,
will be used to review and improve the currently rather large core collection set.
Tapping the genepool
In 1993 the World Beta Network (WBN) recommended to increase evaluation activities
in vegetable beets (Leaf Beet and Garden Beet Group). A comprehensive
evaluation of a Garden Beet Group collection was conducted by BARANSKI et al.
(2001) a few years later. Amongst others, a wide variation for nitrate content (384 –
2894 mg/kg FM) was detected (GRZEBELUS and BARANSKI 2001). Low nitrate content
is a quality character for red beet juice marketed as health product. However, such
evaluation projects are still an exception.
There are actually only two major evaluation activities. A programme for systematic
screening has been set up by the USDA/ARS which is run by the Crop Germplasm
Committee with great success since 1987 (DONEY 1998). Many of the new disease
resistances used today in breeding were first detected in the USA such as the rhizomania
resistance (WHITNEY 1989). The individual sets of accessions vary between
30-60 to limit the yearly workload of participating institutions and the required funds.
The strength of the programme lies in its continuity both in terms of funding and expertise.
Within the European Union or individual member states no such programme exists
for Beta. The council regulation 1467/94 through which the GENRES CT95-42 is being
funded must therefore be considered as a unique chance for germplasm enhancement
of cultivated beets. Between 1996 and 2001, the Beta core collection has
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