Potential phylogenetic utility of the low-copy nuclear gene pistillata in dicotyledonous plants: Comparison to nrDNA ITS and trnL intron in Sphaerocardamum and other Brassicaceae

We report the potential phylogenetic utility of DNA sequence data from the last 700 bp of a ca. I-kb intron of the MADS-box gene pistillata from a sam pling of Sphaerocardamum species and other Brassicaceae. These results are compared with nrDNA ITS and the chloroplast trnL intron for the same taxa t o demonstrate the potential phylogenetic utility of this pistillata intron and to identify potential historically independent sequences for an ongoing study of relationships within Sphaerocardamum. Analyses of the DNA sequenc e data for Brassicaceae indicated that pairwise divergences and potentially informative characters were higher in the pistillata intron (0.6-30.8%, 28 4 characters) and ITS (0-24%, 94 characters) than in the chloroplast trnL i ntron (0-4.2%, 17 characters). A comparison of Sphaerocardamum sequences id entified low divergences and numbers of informative characters for trnL int ron (0-2.4%, 1 character) and nrDNA ITS (0-2.5%, 2 characters) and substant ially more variation among the pistillata sequences (0.15-3.7%, 19 characte rs). Phylogenetic analyses of these pistillata sequences fully resolve ingr oup relationships without character conflict. Results of pistillata PCR amp lifications from a broader dicot sample showed that some primers may be use ful in amplifying orthologous pistil lata sequences. Ultimately this pistil lata intron may be a valuable source of phylogenetic characters at lower ta xonomic levels. (C) 1999 Academic Press.