Biodiversity in Nordic horseradish (Armoracia rusticana)

The biodiversity of horseradish was studied in accessions collected from old gardens in Denmark, Finland, Norway and Sweden. In total 176 accessions were collected.Horseradish, Armoracia rusticana (P. Gaertn., B. Mey. & Scherb.), has been used by man during long time and it was already mentioned in "De material medicia libri quinque" written year 100 AD. The plant, which has its origin in Southeast Europe, was brought to the Nordic countries by monks during the thirteenth century. In the Nordic countries, horseradish was used both as a bitter spice and as a medicinal plant to treat headaches, digestive disorders, high blood pressure and gout.The root has a high content of vitamin C and was often used to prevent scurvy on long sailing tours and as a component in preserving food. Horseradish also contains high levels of sulfur-containing glycosides, so called glucosinolates. Glucosinolates (GLS), or their breakdown products are responsible for the pungent taste and claimed medicinal effects. The dominate GLS in horseradish is sinigrin (>80%) followed by gluconasturtiin and glucobrassicin. Although if the traditional use of horseradish has decreased new areas has developed, as a natural preservative, in medical treatments, in laboratories and in industrial production.Studying the genotypic diversity with AFLP, the results showed a significant genetic diversity among Nordic horseradish. The accessions clustered in accordance with their country of origin with the highest diversity among the Finnish accessions, followed by the Danish accessions.The result from the phenotypic analyses with morphological characters and glucosinolate content showed a high diversity among the studied accessions. In the morphological studies the accessions showed all types of leaf- and root shapes and divided in different clusters. Also a high diversity in the glucosinolate content with both high and low levels of sinigrin and gluconasturtiin were found.No correlation between genotype and phenotypic characters in the Nordic horseradish was revealed. Despite that horseradish is a mainly vegetatively propagated plant the results show a high diversity among the collected accessions.