Inter simple sequence repeat analysis of genetic diversity and relationships in cultivated barley of Nordic and Baltic origin.

This study evaluates putative changes of genetic diversity and relationships of barley in the Nordic and Baltic countries that might have taken place during the last century as a result of commercial breeding. Four ISSR primers were used to analyse 227 accessions, yielding a total of 47 polymorphic loci. Shannon-Weaver diversity values for each locus ranged from 0.012 to 0.693. Overall, there were no significant changes of genetic diversity observed over time. A significant decrease of diversity was, however, observed in material from the southern parts of the Nordic and Baltic countries. In material from the northern parts no decrease of diversity was observed. The genetic diversity of six-rowed barley bred in the middle of the 20th century was low, but there was no significant difference between modern accessions and landraces or old cultivars. The magnitude in changes of genetic diversity differed also in material from different countries of origin. A cluster analysis clearly separated the material into two groups. The first cluster included 86.5% of all six-rowed accessions, whereas the second cluster contained 97.4% of all two-rowed accessions.