Global diversity in barley landraces

Twenty genic- and genomic SSR markers were used to study genetic diversity and geographical differentiation of barley from 29 countries through analysis of 304 worldwide cultivated barley landraces. Out of them, 19 loci were highly polymorphic in the material studied. Based on Nei-distance matrix, Principal Component Analysis (PCoA) and cluster analysis using UPGMA associated with AMOVA the data revealed countries’ grouping within regions. Three distinct germplasm pools were identified in the landraces. The first of these was from Eastern Africa (Eritrea and Ethiopia) and South America (Ecuador, Peru and Chile) suggesting that barley introduced to South America might have originated specifically from East Africa or that they share a common genetic basis for adaptation. The second was the Caucasus (Armenia and Georgia) and the third included the remaining regions of Central Asia, Near East, Northern Africa and Eastern Asia. Genetic diversity of barley subspecies (H.vulgare, H.distichum, H.spontaneum and H.agriocrithon) also discriminates them into three groups: cultivated barleys (H.vulgare and H.distichum), subspecies H.spontaneum and subspecies H.agriocrithon. These data demonstrate that H. agriocrithon and H. spontaneum might be distinct and do not support a hybrid origin for H. agriocrithon to be further investigated on the basis of more intense sampling of the wild relative H. spontaneum and H.agriocrithon.