Genetic relationships of Rhododendron (Ericaceae) in Taiwan based on the sequence of the internal transcribed spacer of ribosomal DNA

The genetic relationships of 20 Rhododendron species in Taiwan was determined based on the sequence of the internal transcribed spacer (ITS) region of ribosomal DNA. Sequences of the complete ITS region including ITS1, 5.8S rDNA, and ITS2, were obtained by direct sequencing of polymerase chain reaction (PCR)-amplified fragments. Gaultheria itoana was used as an outgroup. Aligned sequences of ITS1 and ITS2 from the 21 taxa resulted in 493 characters. According to the dendrogram, six main clusters were classified among the 20 species of the genus Rhododendron in Taiwan. Rhododendron oldhamii, R. nakaharai, R. taiwanalpinum, R. simsii, R. lasiostylum, R. rubropilosum, R. breviperulatum, R. kanehirai, and R. noriakianum were grouped with R. longiperulatum in cluster I. Rhododendron lamprophyllum was grouped with R. ovatum in cluster II. Rhododendron pseudochrysanthum, R. morri, R. hyperythrum, and R. rubropunctatum were grouped with R. formosanum in cluster III. In addition, R. mariesii, R. ellipticum and R. kawakamii formed three independent clusters. In this study, the findings based on ITS sequences are in agreement with the systematics of Rhododendron