AMPLIFICATION OF THE POLYMORPHIC 5.8S rRNA GENE FROM SELECTED AUSTRALIAN GIGARTINALEAN SPECIES (RHODOPHYTA) BY POLYMERASE CHAIN REACTION1

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Abstract
We have initiated comparative studies of ribosomal RNA (rRNA) gene structure to explore its potential to provide taxonomically useful data within the large red algal order Gigartinales. In southern Australia, this group is extremely diverse and includes large numbers of endemic taxa, many of potential economic importance. The 5.8S rRNA gene occurs in the middle region of the ribosomal DNA (rDNA) cistron and is flanked by two internal transcribed spacers (ITSs). These spacers contain regions of DNA, which are highly consented at the generic level and above, interspersed with highly divergent sequences. The 5.8S and associated ITS s of 11 species of Gigartinales (including five species of the largest Australian endemic marine algal genus, Mychodea), plus five taxa belonging to other orders, were amplified by the polymerase chain reaction. The size of the 5.8S rDNA and its flanking ITSs varied not only within and between genera, but also at the species level. However, this rDNA sequence appears to be relatively constant within populations find may be useful as a populational marker.