Genetic diversity of allozymes in turnip (Brassica rapa L. var. rapa) fromthe Nordic area

Genetic diversity and relationships based on isozymes were studied in 31 ac cessions of turnip (Brassica rapa L. var. rapa). The material included vari eties, elite stocks, landraces and older turnip of slash-and-burn type from the Nordic area. A total of 9 isozyme loci and 26 alleles were studied. Th e isozyme systems were ACO, DIA, GPI, GOT, PGM, PGD and SKD. The level of h eterozygosity was reduced in the landraces. but it was high for the variety group 'Ostersundom'. Turnip has a higher genetic variation than other crop s within B. rapa and than in other species with the same breeding system. T he genetic diversity showed that 18.7 % of the genetic variation was within the accessions, and the total H-T value was 0.358. Gpi-1 and Pgd-1 showed the lowest variation compared with the other loci, The cluster analysis rev ealed five clusters, with one main cluster including 25 of the 31 accession s. The dendrogram indicated that the variety group 'Ostersundom' clustered together whereas the variety group 'Bortfelder' was associated with country of origin. The landraces were spread in different clusters. The 'slash-and -burn' type of turnip belonged to two groups.