Complete Mitogenome Sequencing, Annotation, and Phylogeny of Grateloupia turuturu, a Red Alga with Intronic cox1 Gene

The mitochondrial genome (mitogenome) is essential for identifying species and tracing genetic variation, gene patterns, and evolutionary studies. Here, the mitogenome of Grateloupia turuturu was sequenced on the Illumina sequencing platform. This circular mitogenome (28,265 bp) contains 49 genes, including three rRNAs, twenty transfer RNAs (tRNAs), and twenty-six protein-coding genes (PCGs). Nucleotide composition indicates biased AT (68.8%) content. A Group II intronic sequence was identified between two exons of the cox1 gene, and this sequence comprises an open reading frame (ORF) that encodes a hypothetical protein. The gene content, annotation, and genetic makeup are identical to those of Halymeniaceae members. The complete mitogenome sequences of the Grateloupia and Polyopes species were used in a phylogenetic analysis, which revealed that these two genera are monophyletic and that G. turuturu and G. elliptica are closely related. This newly constructed mitogenome will help us better understand the general trends in the development of cox1 introns in Halymeniaceae, as well as the evolution of red algal mitogenomes within the Rhodophyta and among diverse algal species.