XVI International Botanical Congess

The genus Sanguisorba (Rosaceae) includes perennial species with 2n=28 or 2n=56 and an annual, S. annua, with 2n=14, and the formers are considered to be derived from the latter through polyploidizations. The typical diploid plants have at least a pair of 5S rDNA sites, and therefore, tetraploid derived from the diploid is expected to have the multiple number of 5S rDNA sites, i. e. , at least four. In Sanguisorba, however, some tetraploids previously examined have only one pair of 5S rDNA sites.In this study, 1) to elucidate whether 2n=28 plants were derived from 2n=14, a phylogenetic analysis was carried out using matK gene sequences, and 2) to determine the ancestral state of the number of 5S rDNA sites, 5S rDNA FISH was carried out for the species related with tetraploid having only one 5S rDNA locus.