Single nucleotide mutations in promoter and exon region of SOD gene alter heat-tolerance of scallops (Patinopecten yessoensis)

The superoxide dismutase (SOD) is one of classical indices for evaluating stress-resistance capability of multicellular organisms. This study aims to clarify the relationship between SOD expression and heat-tolerance in scallops and identify potential biomarkers for selective breeding of heat-tolerant scallops. The “Mingyue” lineage and regular farmed lineage of the scallop Patinopecten yessoensis were selected as research targets. Heat-susceptible individuals (HS) and heat-tolerant individuals (HT) were observed from “Mingyue” P. yessoensis through gradual heat-stress treatment. The correlation between relative expression of SOD gene and heat-tolerance was preliminarily established for the first time. Single nucleotide polymorphism (SNP) sites related to heat-tolerance were identified in both promoter and exon regions of SOD gene in the “Mingyue” P. yessoensis . Verification experiments were in turn performed in the in regular framed P. yessoensis population. The mechanism by which the identified SNPs in SOD gene affect heat-tolerance of P. yessoensis was subsequently dissected preliminarily. The results revealed that: 1) the relative expression of SOD gene correlated closely with heat-tolerance of P. yessoensis ; 2) two SNP sites (g.–538 A > C and g.–304 T > A) and three SNP sites (c.229 C> T, c.284 C> A, and c.348 C> A) were identified in the promoter and exon region of SOD gene. All identified SNP sites exhibited moderate polymorphism (0.25 ≤ PIC < 0.5), with their distribution conforming to the Hardy-Weinberg equilibrium ( P > 0.05). Compared to the HS group, the dominant genotypes in the HT group were CA (g.–538 A > C), AT (g.–304 T > A), CT (c.229 C > T), CA (c.284 C > A), and CA (c.348 C > A). Bioinformatics analyses indicate that mutation of above identified SNPs may affect the affinity between SOD promoter and transcriptional factors, the stability of SOD mRNA, and the spatial structure of SOD protein.