Complete sequence of chloroplast genome from Sargassum vachellianum (Sargassaceae, Phaeophyceae): Genome structure and comparative analysis

Abstract

Sargassum vachellianum is an ecologically important brown alga. It is China-specific and mainly inhabits in rocky intertidal zones in southeast coastal waters of China. In this study, we sequenced its circular complete chloroplast genome (cpDNA) and compared it with cpDNAs from S. vachellianum, S. horneri and S. thunbergii. The complete S. vachellianum cpDNA was 124,582 bp in length and consisted of a pair of inverted repeats (IRs) of 5435 bp, a large single copy (LSC) region of 73,721 bp and a small single copy (SSC) region of 39,991 bp. Totally 160 genes were predicted, including 132 protein-coding genes, four ribosomal RNA genes and 24 tRNA genes, and the coding sequences contributed 77.48% of the whole genome. In addition, 25 SSR loci and 28 highly variable regions were identified from the S. vachellianum cpDNA, which might be used as candidates for developing DNA barcode markers of Sargassum species. The phylogenetic tree based on datasets of all the plastid-encoded proteins demonstrated that species of S. subgenus Bactrophycus were firstly combined and then clustered with S. vachellianum, which belongs to S. subgen. Sargassum. The results indicate that the chloroplast genomes are good resources for developing new DNA markers for taxonomy, and also as tools for evolutionary research of closely related species in future studies.

Keywords

• Brown alga
• Chloroplast genome
• Phaeophyta
• Sargassaceae
• Sargassum vachellianum