Molecular divergence of the ssu rRNA gene and internal transcribed spacer 1 in Porphyra yezoensis (Rhodophyta)

摘要

Nucleotide sequences from downstream of the small subunit (ssu) rDNA to the internal transcribed spacer 1 (ITS1) region of the individual thalli of both wild-collected Porphyra yezoensis from 3 different sites and culture strains were determined toobtain the molecular features of strains in the P. yezoensis lineage. Wild-collected thalli identified by morphological systematics, included individuals that were separate from the P. yezoensis lineage based on ssu rDNA and ITS1 sequence homologies andphylogenetic relationships constructed using ITS1 sequences. Ssu rDNA exon region nucleotide sequences were identical among the wild-collected and cultured strains of P. yezoensis. However, all individual wild-collected P. yezoensis thalli had differentITS1 sequences, even among individuals from the same sites. Furthermore, two different ssu rDNA structures with and without an intron were found in individuals from the same site. These results indicated the possibility that the presence and sequence ofintrons and ITS1 sequences can be used as a characteristic to determine the origin of culture strains. Four of six culture strains examined had an identical sequence from the ssu rDNA to ITS1, while the sequences of another two strains differed. In thisstudy, wild-collected and culture strain thalli sequences were not identical, although similar pairs were identified.