Plant Systematics and Evolution

, Volume 234, Issue 1, pp 27-51

First online:

Phylogenetic analysis of Stylosanthes (Fabaceae) based on the internal transcribed spacer region (ITS) of nuclear ribosomal DNA

  • J. Vander StappenAffiliated withKatholieke Universiteit Leuven, Laboratory of Gene Technology, Leuven, Belgium
  • , J. De LaetAffiliated withAmerican Museum of Natural History, Division of Invertebrate Zoology, New York, USA
  • , S. Gama-LópezAffiliated withUniversidad Nacional Autónoma de México, Laboratorio de Recursos Naturales, Municipio Tlalnepantla, Estado de México, México
  • , S. Van CampenhoutAffiliated withKatholieke Universiteit Leuven, Laboratory of Gene Technology, Leuven, Belgium
  • , G. VolckaertAffiliated withKatholieke Universiteit Leuven, Laboratory of Gene Technology, Leuven, Belgium

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Abstract.

 Phylogenetic relationships in Stylosanthes are inferred by DNA sequence analysis of the ITS region (ITS1–5.8S–ITS2) of the nuclear ribosomal DNA in 119 specimens, representing 36 species of Stylosanthes and 7 species of the outgroup genera Arachis and Chapmannia. In all examined specimens of any particular diploid and (allo)polyploid species, only a single ITS sequence type was observed. This allowed us to identify a parental genome donor for some of the polyploids. In several diploid and polyploid species, different specimens contained a different ITS sequence. Some of these sequence types were present in more than one species. Parsimony analysis yielded several well-supported clades that agree largely with analyses of the chloroplast trnL intron and partially with the current sectional classification. Discordances between the nuclear and cpDNA analyses are explained by a process of allopolyploidization with inheritance of the cpDNA of one parent and fixation of the ITS sequences of the other. S. viscosa has been an important genome donor in this process of speciation by allopolyploidy.

Key words: Fabaceae, Stylosanthes. Internal trans-cribed spacer region (ITS), molecular phylogeny, allopolyploid, DNA sequence analysis.