ORIGIN AND RELATIONSHIPS OF SAINTPAULIA (GESNERIACEAE) BASED ON RIBOSOMAL DNA INTERNAL TRANSCRIBED SPACER (ITS) SEQUENCES

Phylogenetic relationships of eight species of Saintpaulia H. Wendl, 1 9 species of Streptocarpus Lindl. (representing all major growth forms within the genus), and two outgroups (Haberlea rhodopensis Friv., Chi rita spadiciformis W, T. Wang) were examined using comparative nucleot ide sequences from the two internal transcribed spacers (ITS) of nucle ar ribosomal DNA. The length of the ITS 1 region ranged from 228 to 24 9 base pairs (bp) and the ITS 2 region from 196 to 245 bp; Pairwise se quence divergence across both spacers for ingroup and outgroup species ranged from 0 to 29%. Streptocarpus is not monophyletic, and Saintpau lia is nested within Streptocarpus subgenus Streptocarpella. Streptoca rpus subgenus Streptocarpus is monophyletic. The ITS sequence data dem onstrate that the unifoliate Streptocarpus species form a clade, and a re also characterized by a unique 47-bp deletion in ITS 2. The results strongly support the monophyly of (1) Saintpaulia, and (2) Saintpauli a plus the African members of the subgenus Streptocarpella of Streptoc arpus, The data suggest the evolution of Saintpaulia from Streptocarpu s subgenus Streptocarpella. The differences in flower and vegetative c haracters are probably due to ecological adaptation leading to a relat ively rapid radiation of Saintpaulina.