Enhancement of the genetic diversity in Pelargonium (section Pelargonium) by species introgression

Beside today’s most important Pelargonium cultivars in the groups of Zonal and Ivy Pelargoniums, Regal Pelargoniums (P. ×domesticum L.H. Bailey) and Pelargonium crispum hybrids are attractive ornamental plants with long breeding histories, too. Here, the pedigrees trace back to crosses with only a few species accessions. Despite numerous cultivars, there is only a low level of genetic and phenotypic variation which is experienced in current breeding programs. Thus, modern cultivars of both groups are examples for a funnel effect. The genus Pelargonium offers with over 250 wild species in 16 sections a large genetic diversity. Numerous wild species of the section Pelargonium are characterized by entire different traits in comparison to the common cultivars such as flower traits, habitus or demands on growing conditions. The domestication of these species failed, among others, because of crossing barriers like different ploidy levels and the availability of these resources for cross-combination. Classical and modern methods of plant breeding can make these species available for the application-oriented plant breeding. Preliminary results of interspecific hybridization between species of the section Pelargonium are presented including pollination studies, genetic and molecular investigations.