Genome-wide identification, molecular characterization, and involvement in response to abiotic and biotic stresses of HSP70 gene family in turbot (Scophthalmus maximus)

we identified 16 turbot HSP70 genes at the genome-wide level, and their biochemical properties, subcellular localization and protein structure were illustrated, respectively. Gene structure, motif composition and phylogenetic analysis provided strong evidence for the evolutionary relationship, classification and functional diversity of HSP70 gene family members. 16 turbot HSP70 genes were unevenly distributed on 9 chromosomes. Molecular evolution analysis indicated that the duplicated HSP70 genes in turbot were all under purifying selection. Expression profiles of the HSP70 genes in diverse tissues under five different stresses were comprehensively investigated by examining multiple RNA-seq datasets. Results showed that most of the HSP70 genes were expressed in a stress-specific and tissue-specific expression patterns under both abiotic and biotic stresses. In addition, 10, 6, 8, 10, and 9 HSP70 genes showed significantly up- or down-regulated expression after heat, salinity, and parasitic, bacterial, and viral infection stress, respectively. Among them, hsp70 (hspa1a), hspa1b and hspa5, showed significant responses to all five diverse stresses, indicating their potential roles in comprehensive anti-stress. In addition, qPCR analysis showed that hsp70 (hspa1a), hspa1b and hspa5 were significantly or extremely significant upregulated after both heat and Edwardsiella tarda infection stresses, further validating their involvement in comprehensive anti-stress. This may be the first study that systematically identified and analyzed the HSP70 gene family in turbot.