Mitochondrial genome of Turbinaria ornata (Sargassaceae, Phaeophyceae): comparative mitogenomics of brown algae

Turbinaria ornata (Turner) J. Agardh is a perennial brown alga native to coral reef ecosystems of tropical areas of the Pacific and Indian Ocean. Very little is known about its organellar genome structure. In the present work, the complete mitochondrial genome sequence of T. ornata was determined and compared with other reported brown algal mtDNAs. The circular mitogenome of 34,981 bp contains a basic set of 65 mitochondrial genes. The structure and organization of T. ornata mitogenome is very similar to Sargassum species. Turbinaria ornata genes overlap by a total of 164 bp in 12 different locations from 1 to 66 bp, and the non-coding sequences are 1872 bp, constituting approximate 5.35 % of the genome. The total spacer size has positive correlation with the brown algal mitogenome size with the correlation coefficient of 0.7972. Several regions displaying greater inconsistency (rnl-trnK spacer, cox2 gene, cox3-atp6 spacer, rps14-rns middle region and trnP-rnl spacer) have been identified in brown algal mtDNAs. The observed uncertainty regarding the position and support values of some branches might be closely associated with the heterogeneity of evolutionary rate.