engleski

Hop genetic research in Slovenia

The Institute of Hop Research and Brewing (IHRB) maintains an extensive collection of worldwide hop cultivars and their own breeding lines and a fairly rich collection of wild hops. These genetic resources have been evaluated by morphological and biochemical descriptors and additionally by molecular markers, thus providing more accurate and detailed information than classical phenotypic data. Hop cultivars maintained at the IHRB collection have been evaluated by RAPD, AFLP and microsatellite (SSR) markers. The main characterization of the hop germplasm under study was observed e.g. a clear geographic division of cultivars into American and European genotypes and a distinct grouping within European germplasm reflecting past hop breeding practices adopted in different regions. In order to gain additional hop genomic information, the development of hop microsatellite markers was undertaken. The establishment of a microsatellite analysis system for a new species is a considerable financial and technical challenge. However, microsatellites have been proven to be markers of choice in many crops because of their abundance and uniform distribution in genomes, hypervariability, co-dominant nature, transportability among species and accessibility for other research laboratories. Only four microsatellite loci have been identified in hop to date, but their good properties and applicability have already been shown in genetic diversity and fingerprinting studies, and in attempts to create a hop genetic linkage map. More microsatellite loci are required to increase knowledge of the hop genome, and particularly to develop a reliable genetic map. We have also started making a map of the family of 120 progenies from a previous cross (Magnum x 2/1 - wild Slovene male) characteristic for the variability of alpha acid content. We are using AFLPs as molecular markers, applying two different restriction enzymes (Eco RI and Pst I) in combination with the standard one (Mse I) to avoid clustering of the Eco RI/Mse I markers around centromers. We have analysed 18 primer pair combinations so far, generating around 400 polymorphic markers, but they are not yet evaluated. We hope to increase the number of primer combinations to 30 and additionally to include as many microsatellite markers as possible. We thus hope that a saturated hop map can be constructed and used primarily for the delineation of QTL governing alpha acid content. In addition to this map, we are analysing another mapping family for aphid resistance and building families for Verticillium resistance.

Humulus lupulus L.; genetic resources; molecular markers; genetic map; QTLs

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