Molecular diversity and association mapping of quantitative traits in Tibetan wild and worldwide originated barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) germplasm

Molecular diversity of 40 accessions of Tibetan wild barley (TB), 10 Syrian (SY), 72 North American (NA), 36 European (EU), 9 South American (SA) and 8 Australian (AU) varieties were characterized using multiple microsatellite loci. The 42 SSR primers amplified 278 alleles across the 175 barley accessions tested in the present study. The average gene diversity for the whole sample was 0.3387 whereas the mean value for the each population was as follows: TB = 0.3286, SY = 0.2474, EU = 0.299, AU = 0.2867, NA = 0.3138, SA = 0.2536. Clustering analysis based on Nei’s original genetic distance showed that the EU and NA barley populations were grouped together. The TB population was well separated from the other 5 barley populations. Associations between microsatellite markers and 14 quantitative traits were also investigated. Significant associations were found for 18 microsatellite marker loci. The number of marker loci associated with each trait ranged from one (stem diameter, filled grains per plant, grain weight per plant, length of main spike and awn length) to seven (plant height). The percentage of the total variation explained by each marker ranged from 4.59% (HVM2 associated with plant height) to 17.48% (Bmac90 associated with density of main spike). This study provides candidate markers for further QTL mapping of these traits and for marker-assisted selection.