The application of sequences of the ribosomal cistron to the systematics and classification of the florideophyte red algae (Florideophyceae, Rhodophyta)

This review discusses the impact that molecular studies of the genic and sp acer regions of the ribosomal cistron have had on the systematics and class ification of the florideophyte red algae. Each ribosomal cistron consists o f a nontranscribed spacer region (NTS), an external transcribed spacer regi on (ETS), the small-subunit (SSU) rRNA gene, internal transcribed spacer (I TS 1) region 1, the 5.8S rRNA gene, internal transcribed spacer (ITS 2) reg ion 2, and the large-subunit (LSU) rRNA gene. To date, molecular investigat ions on the Rhodophyta that utilize the ribosomal cistron have been based l argely on the SSU and, to a lesser extent, the ITS regions. We then outline the methods and procedures we use to obtain sequence data from the various regions of the ribosomal cistron. A discussion of recent advances in flori deophyte systematics within the four florideophyte lineages outlined by Sau nders st Kraft (1997) is presented. We then close the review with an introd uction to, and discussion of the potential utility of sequences of the LSU for resolving relationships within the Rhodophyta.