Mitochondrial genome of Sargassum thunbergii : conservation and variability of mitogenomes within the subgenus Bactrophycus

In the present study, we sequenced and annotated the complete mitochondrial genome of S. thunbergii . The circular S. thunbergii mitogenome is 34,748 bp in size and contains the same set of 65 genes as other mtDNAs in four Sargassum species.

The genome organization including the gene order, overlapping regions between genes and the total length of inter-genic regions is highly similar to the other Bactrophycus species. The comparison by genome scale alignment displays only minor differences in gene lengths, but higher divergence in inter-genic spacer regions, especially the cox3-atp6 inter-genic spacer. Mitochondrial phylogenomics suggests that S. thunbergii is tightly combined with Sargassum muticum and Sargassum hemiphyllum forming the sect.