Molecular systematic reassessment of Sargassum (Fucales, Phaeophyceae) in Korea using four gene regions.

摘要

Sargassum is an ecologically and economically important brown alga in East Asia. A total of 28 species are listed in the available literature for South Korea. To identify the species and evaluate the phylogenetic relationships of Korean Sargassum, we analyzed ITS2, rbcL, psaA, and cox3 sequences from a subset of 50 specimens assigned to 22 Sargassum species; sequences of Korean-collected Myagropsis myagroides and Coccophora langsdorfii were also included. We reconstructed the phylogeny of Sargassum using the concatenated dataset. The Korean Sargassum species fell into two subgenera: 19 species were assigned to S. subgen. Bactrophycus and three species to S. subgen. Sargassum. The species in the S. subgen. Bactrophycus represented the sections Halochloa, Hizikia, Spongocarpus, and Teretia, whereas those of S. subgen. Sargassum represented the sections Binderiana and Sargassum. All Korean Sargassum species identified in the present study are part of the East Asiatic complex of species co-occurring in Japan and surrounding areas. Our four-gene dataset was highly resolved at the sectional level and confirmed recently proposed revisions within the genus. The present study is the first comprehensive phylogenetic analysis of Sargassum using four molecular markers.