Genetic variation of common ash (Fraxinus excelsior L.) populations from provenance regions in southern Germany by using nuclear and chloroplast microsatellites

The genetic structure of 14 populations from three ash provenance regions (Fraxinus excelsior L.) in southern Germany (Aid Infodienst, 2003) is described by analysing the variation of four nuclear and five cpDNA microsatellites. The study of the nuclear microsatellites revealed high levels of genetic diversity but low levels of genetic differentiation, suggesting a high degree of gene flow among regions and/or human interference by introducing plant material coming from different provenances. The distributions of the allele frequencies and the genetic structures at these four microsatellite loci did not allow the identification of distinct provenance regions, although "private alleles" were encountered with moderate to low frequencies (above 5 percent). Specifically, the Rhine valley populations (provenance region 81105) and these from the Swabian Jura and Black Forest (provenance region 81107) revealed private alleles at the two microsatellite loci Femsat14 and Femsat112. A more distinct differentiation between provenances was found based on the cpDNA markers. Evidence on genetic delineation and characterization of ash provenances is discussed. Based on these results, provenance regions can be genetically characterised but further analysis of ash populations and of reproductive material (seeds or seedlings) would be of great importance for provenance delineation, as well as gene conservation and sustainable management of ash populations.