Complete mitochondrial genome of Skeletonema marinoi (Mediophyceae, Bacillariophyta), a clonal chain forming diatom in the west coast of Korea

The complete mitochondrial DNA of common planktonic diatom, Skeletonema marinoi JK029 was sequenced and characterized. The circular mitogenome contains 62 genes in 38 515 bp (29.7% GC), including 35 protein-coding, 2 rRNA, and 25 tRNA genes. Total 80% of protein coding genes have usual ATG start codon and 20% have alternative start codons. The GC content of tRNA genes (39.8%) is relatively higher than those of the rRNA (32.9%) and CDS (29.3%). There are four cases of gene overlapping between neighboring genes, i.e., rrs-trnM, rps2-rps4, nadl-tatC, and rps11-trnY. Newly determined mitogenome of S. marinoi was compared with available seven diatoms and eight stramenopiles by using the maximum likelihood analysis. The 34-CDS concatenated data (8528 amino acids) support the monophyly of Bacillariophyta. However, mitogenome data showed different higher class-levels clustering with previous study. These results suggested that additional mitogenome data will provide useful information for mitochondrial genome diversity and evolution of the diatoms and stramenopiles.