Schriften zu Genetischen Ressourcen - Genres

R. V. BOTHMER, TH. V. HINTUM, H. KNÜPFFER and K. SATO
The migration and adaptation of barley to new environments resulted in a complex
picture of ecogeographical types over the world, recognised by morphological,
agronomical and adaptive traits (cf. KNÜPFFER et al. 2002).
Modern plant breeding started with simple selections from the older landraces. The
current cultivars of Europe are to a great extent the result of the earlier, first selections
and cross-breeding of a restricted number of lines. This means that modern
varieties would be genetically depauperated and have a very narrow genetic base
(see below). Exotic material has had a restricted use in breeding in Europe, but could
nevertheless have had a considerable influence on the present genetic diversity
pattern in pedigrees of modern cultivars (FISCHBECK 2002).
Present status of diversity in barley
Even though there is a wealth of data accumulating on genetic variation in cultivated
barley it is not an easy task to obtain an overview of the entire diversity pattern in
time and space. This shortcoming has several reasons:
• Although a considerable amount of marker data has been generated by now, individual
data sets pertain only a restricted number of accessions and are usually
based on a unique marker set. Hence, it is at present not possible to pool data in
order to further complete the picture of structure and diversity of the genepool
(GRANER et al. 2002).
• It is difficult to get a good estimate of the diversity in cultivated barley, since continuous
breeding efforts have caused the formation of regional and temporal diversity
patterns, which reflect several factors, such as cropping system (winter vs.
spring forms), end use (feed vs. malt) and the strategy of individual breeders to
rely on distinct progenitors (FISCHBECK 2002).
• Different sets of data, even based on the same material, may show conflicting
pictures such as diversity for resistance or adaptive traits compared to a marker
system. This may be caused by different selection pressures.
• No attempts have been made to develop modern bioinformatics methods to cover
these areas.
Despite methodological shortcomings and other difficulties it is, nevertheless, possible
to elucidate some obvious tendencies in the amount and distribution of genetic
diversity in barley. Wild and weedy forms as well as primitive, domesticated material
are still abundant in certain areas. Ssp. spontaneum is common in nature in the Middle
East, and landraces are frequently planted in parts of Central and SW Asia as
well as in N Africa, where barley is a staple food. The genetic diversity shows a sig-
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