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The Application of Sequence Analysis of rDNA Fragment to the Systematic Study of the Subfamily Cyrtandroideae (Gesneriaceae)

WANG Xiao-Quan, LI Zhen-Yu   

  • Received:1900-01-01 Revised:1900-01-01 Online:1998-03-10 Published:1998-03-10
  • Contact: WANG Xiao-Quan

Abstract:

 A molecular phylogeny of the subfamily Cyrtandroideae represented by five genera
of four tribes was constructed using sequence analysis of the internal transcribed spacers
(ITS) and partial 5.8 S rRNA gene (3’end) of nuclear ribosomal DNA. Direct PCR
sequencing method was used in the study. The sequences of ITS-1 in the five species range
from 234 bp to 258 bp in size and those of ITS-2 from 218 bp to 246 bp. The ITS-1 (258
bp) and ITS-2 (218 bp) of Whytockia bijieensis differ greatly from those of the other species
in size, sequence and G + C content, and therefore the tribe Klugieae represented by W.
bijieensis may have diverged from the ancestor of the subfamily Cyrtandroideae at a very
early time. In PAUP analysis, W. bijieensis was used as the functional outgroup, and only
one most parsimonious Fitch tree was obtained through exhaustive search. The tree has 353
steps, with CI = 0. 932 and RI = 0. 529. In the tree,  Chirita crassifolia is basal to a
monophyletic group comprising Cyrtandra umbellifera,  Briggisia longipes and Anna
mollifolia, and the monophyletic group is strongly supported by the bootstrap value (97).
The tribes Trichosporeae and Cyrtandreae represented respectively by Anna mollifolia and
 Cyrtandra urnbellifera both evolved from the tribe Didymorcarpeae, which can explain why
many intermediate taxa exist among the three tribes. According to this, the present authors
suggest that the tribe Trichosporeae and the tribe Cyrtandreae be merged with the tribe
Didymocarpeae.

Key words: Cyrtandroideae, Internal transcrlbedspacers(ITS), Molecularphylogeny

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