Barley Temporal Diversity Changes in Nordic and Baltic Genetic Erosion a Reality?

Barley (Hordeum vulgare L. ssp. vulgare) is an important crop in the Nordic and Baltic countries, where it is mainly used for feed and malt. Commercial breeding of barley has been carried out in this region for more than a century, and landraces have been completely replaced by pure line cultivars. There is a concern that plant breeding might lead to a severe reduction of genetic diversity, so-called genetic erosion, since commercial breeding was initially based only on a few successful selections from landraces. The consequences of such erosion would affect plasticity of the crop, which might reduce its ability to adapt to future agriculture and consumption demands and increase the vulnerability to epidemics. The aim of this study was to evaluate the degree of putative genetic erosion and relationships in Nordic and Baltic barley material. A large collection representing landraces and cultivars from the end of the 19th century up to modern material were analysed by isozymes and DNA markers. In addition, field trials were performed in order to observe changes in the diversity of agronomic traits. General indications of a decrease in diversity were observed. A loss of less common alleles was found in molecular markers and a significant decrease of variability was detected for most agronomic traits. However, the molecular markers failed to prove significant diversity changes in the material as a whole. New alleles, not present in Nordic and Baltic landraces and old cultivars, were found in modern material. Differences in the magnitude of diversity varied depending of country and regio