Monophyly of the aneuploid species of <i>Astragalus</i>: Evidence from nrDNA internal transcribed spacer sequences

TitleMonophyly of the aneuploid species of Astragalus: Evidence from nrDNA internal transcribed spacer sequences
Publication TypeJournal Article
Year of Publication1993
AuthorsWojciechowski MF, Sanderson MJ, Baldwin BG, Donoghue MJ
JournalAmerican Journal of Botany
KeywordsBiological Sciences, Botany & Plant Sciences

Evolutionary relationships within Astragalus L. (Fabaceae) were inferred from nucleotide sequence variation in nuclear ribosomal DNA of both New World and Old World species. The internal transcribed spacer regions (ITS) of 18S-26S nuclear ribosomal DNA from representatives of 26 species of Astragalus, three species of Oxytropis DC., and two outgroup taxa were analyzed by polymerase chain reaction amplification and direct DNA sequencing. The length of the ITS 1 region within these taxa varied from 221 to 231 bp, while ITS 2 varied in length from 207 to 217 bp. Of the aligned, unambiguous positions, approximately 34% were variable in each spacer region. In pairwise comparisons among Astragalus species and outgroup taxa, sequence divergence at these sites ranged from 0 to 18.8% in ITS 1 and from 0 to 21.7% in ITS 2. Parsimony analyses of these sequences resulted in a well-resolved phylogeny that is highly concordant with previous cytogenetic and chloroplast DNA evidence for a major phylo