Genome-wide identification and expression analysis of the superoxide dismutase (SOD) gene family in Salvia miltiorrhiza

Adverse environmental conditions, such as salinity, cold, drought, heavy metals, and pathogens affect the yield and quality of Salvia miltiorrhiza, a well-known medicinal plant used for the treatment of cardiovascular and cerebrovascular diseases. Superoxide dismutase (SOD), a key enzyme of antioxidant system in plants, plays a vital role in protecting plants against various biotic and abiotic stresses via scavenging the reactive oxygen species produced by organisms. However, little is known about the SOD gene family in S. miltiorrhiza. In this study, eight SOD genes, including three Cu/Zn-SODs, two Fe-SODS and three Mn-SODs, were identified in the S. miltiorrhiza genome. Their gene structures, promoters, protein features, phylogenetic relationships, and expression profiles were comprehensively investigated. Gene structure analysis implied that most SmSODs have different introns/exons distrbution patterns. Many cis-elements related to different stress responses or plant hormones were found in the promoter of each SmSOD. Expression profile analysis indicated that SmSODs exhibited diverse responses to cold, salt, drought, heavy metal, and plant hormones. Additionally, 31 types of TFs regulating SmSODs were predicted and analyzed. These findings provided valuable information for further researches on the functions and applications of SmSODs in S. miltiorrhiza growth and adaptation to stress.