RFLP diversity within and between major groups of barley in Europe

Restriction fragment length polymorphism (RFLP) diversity has been determined and analyzed as expressed by 33 single- or low-copy clone/enzyme combinations at 32 loci distributed over all chromosomes of the barley genome within a sample of 223 European barley accessions comprised of pure line (single-head progenies) genotypes. The accessions have been selected to include landraces and widely grown cultivars derived from crossbreeding during the 20th century in North-, West- and Central European countries. Genetic diversity obtained from 83 alleles across all accessions is characterized by the diversity index H = 0.385. The diversity indices determined for landraces and cultivars were almost equal, with the difference between spring (H = 0.260) and winter (H = 0.415) barley approaching statistical significance, while comparisons of other groupings only revealed statistically insignificant trends. A more detailed analysis based on differences in allele frequency distributions at each locus (clone/enzyme combinations resp.) revealed very clear differences related to the existence, continuity and dynamics of changes in group-specific RFLP profiles. With the majority (69%) of RFLP alleles at 23 out of 32 loci on all barley chromosomes involved, contributions from chromosomes 1H, 3H, 4H and 5H seem to be of special importance. Differences in the overall average of abundance indicate higher levels of genetic diversity within both groups of winter barley compared with both groups of spring barley, from which the most frequent alleles at 15 (2-rowed spring barley) and 17 (6-rowed spring barley) RFLP loci approach fixation. The results of this study are discussed in relation to the history of barley Cultivation and barley breeding in Europe, and possible explanations for group-specific differences in the RFLP profiles of landraces and cultivars as well as for the high levels of (nearly) fixed alleles of both subsets of spring barley, and with respect to progress in barley breeding that it has been possible to obtain within the rather narrow RFLP profiles.