Microsatellite (SSR) alleles (A-K) of locus 5-2.
The world collection of hop cultivars was first assessed by RAPD markers (Šuštar-Vozlič and Javornik, 1999), and subsequently by AFLP and four SSR markers (Jakše et al., 2001). These studies have well documented the presence of two geographically distinct germplasms in hop cultivars – European (EU) germplasm characterised by its fine aroma and North American (NA) germplasm characterised by a distinct bitter taste. Within European germplasm, a distinct grouping of accessions was also established reflecting the history of past hop breeding practices adopted in different European hop growing regions. Work on hop genetic resources has been extended to studies of wild hops and male and female breeding lines using four SSR markers (Jakše et al., 2004), since wild hops have been the source of many important genes. The geographic classification of hop germplasm into European and North American has been confirmed not only by microsatellite allele distribution and analysis of genetic distances, but also by notable differences in the structure of allele sequences. Molecular analysis failed to distinguish between female and male hops but results showed variability present within each of the hop geographic groups, indicating very high genetic variability within NA wild hops. The genetic diversity between wild European hops and hop cultivars was smaller, indicating a relatively narrow genetic base of the existing EU gene pool for hop breeding.