The effectiveness of these conservation approaches depends upon the criteria used for selecting germplasm and it has been suggested that genetic diversity may not always be optimal in these, or equivalent collections in other crops .
Elnura 32 dating
The 16 SSR markers amplified a total of 369 alleles across the 1,859 apple accessions used for diversity analysis, ranging from 17 (CH02c09 and CH05f06) to 35 (CH02c06) alleles per locus.
The average number of alleles per locus was 23.06, whereas the mean effective number of alleles per locus was 6.59 (Table ).
This is the largest study of apple genetic resources at the pan-European level.
Among the 2,446 accessions, ten accessions did not show clear PCR amplifications and were discarded from the analysis.
The first level of stratification revealed an asymmetric division of the germplasm among the three groups, and a clear association was found with the geographical regions of origin of the cultivars.
The substructure revealed clear partitioning of genetic groups among countries, but also interesting associations between subgroups and breeding purposes of recent cultivars or particular usage such as cider production.
In brief, the Northern Eastern region was composed of germplasm originating in Nordic European countries plus Russia, the Western region was composed of germplasm originating in Western and Central European countries and the Southern region was composed of germplasm from Spain and Italy (see Methods for more details).
The remaining 11 % consisted of either genotypes lacking passport information or genotypes with contradictory information in passport data from different origins.
The amount and structure of genetic diversity in dessert apple germplasm conserved at a European level is mostly unknown, since all diversity studies conducted in Europe until now have been performed on regional or national collections.