XVI International Botanical Congess

Genomic in situ hybridization (GISH) and chloroplast DNA sequencing were used to investigate the genomic origin and organization of the alpine grass Poa jemtlandica. Using genomic probes of P. alpina and P. flexuosa, GISH distinguished between the two putative parental genomes and thus confirmed the hybrid nature of P. jemtlandica. The chloroplast trnL intron and trnL-trnF intergenic spacer (IGS) sequence genotypes of P. flexuosa and P. jemtlandica were identical, but differed from those of P. alpina, pointing out P. flexuosa as the maternal parent of P. jemtlandica. GISH revealed the presence of intergenomic translocations in the hybrid genome, indicating that the two parental genomes have undergone rearrangements following hybridization. It is likely that some of these chromosome changes have taken place soon after hybridization in order to overcome the adverse interactions between the nuclear and the cytoplasmic genomes and to facilitate the successful establishment of the newly formed hybrid.