Molecular genome analyses as tools for efficient ex situ-conservation and utilization of plant genetic resources

The potential of molecular markers in augmenting the information available on plant genetic resources is applicable to several aspects of ex situ-genebank work. Gaps in the passport data of the accessions, e.g. on taxonomic status and geographic origin, are a primary target, the latter being especially present in material collected in earlier times and/or exchanged several times between various donors. In addition, molecular analyses offer insight into the diversity present within collections and even into the evolution of certain cultivated plant species. With regard to taxonomy and geographic origin of accessions, species from the very variable and closely related Solanum nigrum complex were studied at the IPK using AFLPs. This led to a classification of more than a dozen formerly undetermined accessions, and, in addition, revealing S. americanum as being unrelated to the other species of the complex and exhibiting unexpected high levels of intraspecific variation. Simultaneously, geography-correlated subclusters in the species S. americanum and S. villosum are detectable. Similar links between geography and molecular clusters were observed in Malus sieversii as (one of) the main progenitor species of cultivated apple from Central Asia: PCR markers lead to a mainly location-specific grouping, the molecular distances between the clusters being even in rather good accordance with their geographic distance. In the genus Amaranthus, genetic diversity assessment confirmed the existence of three genepools. The detected species-specific clusters also offer potentials for future DNA-based classification of material from morphologically similar species.