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Collection priorities and strategy
Unfortunately, the valuable genetic diversity of the natural
populations of wild relatives of cereals is subjected to severe
genetic erosion, particularly in wild wheats. The most detrimental
factor is overgrazing by small ruminants, which is ubiquitous in most
parts of the Near East. The other negative factor is the loss of
original habitats resulting from soil reclamation projects, changes
in agronomic practices (fallow replacements) and urbanization.
Therefore, ICARDA gives high priority to collection and conservation
of the wild relatives of wheat and barley. In the last six years, the
Genetic Resources Unit at ICARDA has conducted more than 20
collection missions focused on the cereal wild relatives which
yielded about 2500 new population samples. These and other accessions
donated by other gene banks or institutions make the present total of
ICARDA holdings as follows: 1608 accessions of wild barley, 1208
accessions of wild Triticum and 2783 accessions of
Aegilops spp. (Table 1).
Recent research at ICARDA revealed that large natural populations of
wild progenitors of wheat and barley consisting of millions of
individuals display extremely high genetic diversity which cannot be
adequately sampled and maintained in an ex situ collection in
the gene bank. Therefore, ICARDA, in cooperation with national
programs, has developed a proposal for conserving the most diverse
populations on site (in situ). This dynamic method of
germplasm conservation would complement the ex situ
collections and allow further development in response to changing
climatic and other conditions.
Landraces or farmers' varieties of cultivated wheat and barley
originating from the West Asia and North Africa (WANA) region receive
the highest priority in ICARDA's collection strategy. There are two
main reasons for giving a special attention to this type of
germplasm: i) genetic erosion caused by their replacement by improved
varieties, and ii) good adaptation to the stressful and highly
variable environments of the West Asia and North Africa region which
is mandated to ICARDA.
It is estimated that landraces make up 80% of ICARDA cereal germplasm
holdings.
The unpredictable year-to-year fluctuations of weather in the WANA
region and the way in which the landraces are reproduced by the
farmers resulted in high genetic diversity. Therefore, landraces are
heterogenous in many characters and are composed of a number of
genotypes and can, therefore, provide more genetic diversity for
plant breeding programs than improved varieties. In fact, a number of
improved varieties of cereals have been developed by ICARDA either as
a direct single-plant selections from WANA landraces or from a cross
in which a landrace or a line derived from it was used as a
parent.
In the recent years, the Genetic Resources Unit at ICARDA focused on
filling the gaps in the geographical representation of countries of
the WANA region in its collections. This effort resulted in the
collection of a good representation of most of the countries in
barley, durum wheat and their wild relatives (Table
1).
All germplasm accessions of barley and durum wheat in the ICARDA
collections have been characterized and/or evaluated for a number of
descriptors and the results were published in a durum wheat catalog
and barley catalog vol. I and II.
The cereal genetic resources are maintained at GRU/ICARDA in a
medium-term active and long-term base collections and all unique
accessions were safely duplicated at CIMMYT, Mexico in 1990.
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