SSR allelic diversity changes in 480 European bread wheat varieties released from 1840 to 2000.

A sample of 480 bread wheat varieties originating from 15 European geographical areas and released from 1840 to 2000 were analysed with a set of 39 microsatellite markers. The total number of alleles ranged from 4 to 40, with an average of 16.4 alleles per locus. When seven successive periods of release were considered, the total number of alleles was quite stable until the 1960s, from which time it regularly decreased. Clustering analysis on Nei's distance matrix between these seven temporal groups showed a clear separation between groups of varieties registered before and after 1970. Analysis of qualitative variation over time in allelic composition of the accessions indicated that, on average, the more recent the European varieties, the more similar they were to each other. However, European accessions appear to be more differentiated as a function of their geographical origin than of their registration period. On average, western European countries (France, The Netherlands, Great Britain, Belgium) displayed a lower number of alleles than southeastern European countries (former Yugoslavia, Greece, Bulgaria, Romania, Hungary) and than the Mediterranean area (Italy, Spain and Portugal), which had a higher number. A hierarchical tree on Nei's distance matrix between the 15 geographical groups of accessions exhibited clear opposition between the geographical areas north and south of the arc formed by the Alps and the Carpathian mountains. These results suggest that diversity in European wheat accessions is not randomly distributed but can be explained both by temporal and geographical variation trends linked to breeding practices and agriculture policies in different countries.

[Genealogical approach to the formation of the winter wheat core collection]. / Genealogicheskii podkhod k formirovaniiu sterzhnevoi kollektsii ozimoi pshenitsy.

The correctness of the genealogical approach to the estimation of genetic diversity has been substantiated. The approach implies a comparison of the estimates of similarity based on genetic markers and coefficients of parentage. A method of the application of the genealogical approach to the formation of the core collection has been developed. The adequacy of the core set has been estimated using Shannon's diversity index adapted for genetic profiles and the correlation between the distributions of ancestors' contributions. A core collection has been formed. This collection contains 25% of the accessions of the original winter wheat (Triticum aestivum L.) collection from the Czech Genebank and represents 70-76% of the intracluster diversity. A decrease in intercluster diversity has not been found in the core collection.