Complete mitochondrial genome of Coscinodiscus granii (Coscinodiscophyceae, Bacillariophyta)

Abstract

Coscinodiscus is a genus common in marine phytoplankton, with some species thought to have a significant negative ecological impact. However, the availability of their genome sequences is rather limited. Here, we assembled and annotated the first complete mitochondrial genome (mtDNA) of the species Coscinodiscus granii L.F.Gough 1905, as part of our efforts to gain a better understanding of the genetic characteristics of Coscinodiscus taxa at a genomic level. The circular mtDNA was 34,970 bp in length and encoded 60 genes, including 32 protein-coding genes (PCGs), 24 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and two conserved open reading frames (orfs). The overall GC content of C. granii mtDNA was 24.30%, which was slightly lower than that of C. wailesii (25.00%), the first species in the genus Coscinodiscus whose mtDNA has been reported, and higher than that of Melosira undulata (21.60%), the first species in the class Coscinodiscophyceae whose mtDNA has been reported. As expected for congeneric species, phylogenetic analysis using concatenated amino acid sequences of 27 shared PCGs suggested that C. granii has a closer evolutionary relationship with C. wailesii. Coscinodiscus was found to be monophyletic in the phylogeny. The complete mtDNAs of more Coscinodiscus species will facilitate the exploration of the evolutionary relationships of species in the Class Coscinodiscophyceae.

Genetic Diversity and Geographical Distribution of the Red Tide Species Coscinodiscus granii Revealed Using a High-Resolution Molecular Marker

“…The circular mtDNA (CNS00554) of C. granii was 34,970 bp in size (GenBank accession number: MW435847). The annotation of protein coding genes (PCGs), transfer RNA (tRNA) genes, ribosomal RNA (rRNA) genes, and open reading frames ( orf s) was conducted using Open Reading Frame Finder (ORF finder) with SmartBLAST and BLASTP, tRNAscan-SE, and MFannot [ 9 ].…”

“…Coscinodiscus granii L.F. Gough 1905 is a cosmopolitan Coscinodiscus species [ 8 ]. Coscinodiscus granii plays an important role in the marine ecosystem and has an important impact on the carbon pool because of its relatively large cell sizes and high carbon content [ 9 ]. Coscinodiscus granii has been found to form characteristic autumn red tides in the Baltic Sea and exist at high densities in spring and summer in the North European Seas [ 10 , 11 ].…”

“…In this project, we aimed to develop a molecular marker with both high resolution and high specificity for distinguishing C. granii strains through comparative analysis of C. granii mtDNAs. Taking advantage of the recently constructed mtDNA [ 9 ] as the reference sequence, we identified intra-species genome variations (GVs) among six C. granii strains. We also tested the applicability of this new molecular marker in probing C. granii genetic diversity in the coastal waters of China.…”