The evolution of the sequences of the internal spacer of nuclear ribosomal DNA for American species in the genus Nicotiana

: Phylogenetic relationships of 46 Nicotiana species were estimated from the sequences of internal transcribed spacer region of nuclear ribosomal DNA. Phylogenetic tree, built by parsimony method, was highly concordant with the conclusions of morphological and cytogenetical investigations. The reliability of dendrogram obtained was assessed by both bootstrap and jackknife analyses.