Assessing the allozyme variation in cultivars and Swedish landraces of rye(Secale cereale L.)

Genetic interpretation and diversity of 9 isozyme loci have been estimated in 7 improved varieties and 19 landraces from Sweden by means of starch gel electrophoresis, The isozyme systems were AGO, DIA, GPI, MDH, PGD and PGM. For the statistic analysis we used the following measures: average number of alleles per locus, percentage of polymorphic loci, average heterozygosit y direct count and average heterozygosity Hardy-Weinberg expected unbiased estimate. The measures were made on species and population levels. The dist ribution of the total genetic diversity among populations was also calculat ed. To illustrate the genetic relationships among populations, genetic dist ances were measured and principal component analysis performed. As expected in a cross-pollinated crop we found high genetic diversity and a larger variation within than among the populations. Somewhat unexpectedly , however, we found that the currently used varieties have the same high le vel of heterozygosity as the landraces but in the dendrogram the two groups are separated. The dendrogram showed three main clusters. The large cluste r included 21 populations and the two small clusters were clearly distingui shable from the rest. The landrace spring-type could not be separated from the landraces winter-type, but we did detect a difference between different spring types. A few populations had unique alleles for certain loci.