show Abstracthide AbstractLoktanella salsilacus is a typical polar-enriched genus of marine Roseobacter. Hence, L. salsilacus 1A07893 and 1A07899, isolated from Chukchi Sea in the Arctic region, were selected as the model bacteria to investigate polar-adapted mechanisms of Roseobacter clade. In this project, multi-omics data of two L. salsilacus were uploaded to support our findings, which contains the complete genomes of two L. salsilacus constructed by PacBio Sequel platform with Illumina NovaSeq PE150 and their transcriptional responses to the temperature downshift. These data identified that upregulated TCA cycle, increased respiratory chain components and the preferential use of monosaccharide play crucial roles in the cold-adaptation of L. salsilacus.