The Molecular Characteristics of Five Genera of Dictyotaceae (Phaeophyta) from Australia: based on DNA Sequence of Nuclear rDNA Internal Transcribed Spacer (ITS) and 5.8S

Algae > Volume 11(4); 1996 > Article

Algae 1996;11(4): 381-388.

Wook-Jae Lee, Robert J. King

Department of Biology, Seoul National University, School of Biological Science, The University of New South Wales

ABSTRACT

The primary nucleotide sequence for rDNA ITS1 and 5.8S for six species of Dictyotaceae from Australia was assessed. ITS1 region is 269 base pairs long and shows two patterns: the one, largly conserved and exhibiting little difference in number of base pair substitutions in four species Dictyota dichotoma, Dilophus marginatus, D. intermedius and Dictyopteris acrostichoides and the other in Padina tenuis and Zonaria crenata showing a very divergent ITS1 region. The ITS2 sequence (268 base) had similar length to that of ITS1 in all six species. The ITS2 sequences in Z. crenata includes two large inserion/deletion that accounted for the divergence of ITS2 of Z. crenata. The ITS2 of Dic. acrostichoides showed more similarity to those of Dictyota-Dilophus than to those of Z. crenata and P. tenuis. The level of ITS sequence variation will make them useful for species and subspecies comparisons within the Dictyotales but render them inappropriate for higher-level phylogenetic comparisons due to alignment problems. 5.8S rRNA gene were estimated to be 158 nucleotide base pairs long, with several insertions and gaps. It is very conserved among the species examined except for Z. crenata, and does not align with the separation of Dictyoteae and Zonarieae on the basis of morphological differences.

Key words: Dictyotaceae, 5.8S, ITS, nuclear DNA, nucleotide sequence