The Identification and Expression Analysis of the Liriodendron chinense (Hemsl.) Sarg. SOD Gene Family

Superoxide dismutase (oxide dismutase) is an enzyme synthesized via the expression of SOD-related genes. It is the first line of defense against oxygen free radicals, and it widely exists in the cytoplasm, chloroplasts, and mitochondria. However, the SOD gene family of woody plant Liriodendron chinense has not been studied. To reveal the potential role of SOD genes, we systematically identified and analyzed the SOD gene family of L. chinense, and investigated the transcriptional responses of LcSOD genes to several abiotic stresses, including cold, heat, and drought. A total of eight SOD genes were identified, namely, five Cu/Zn-SODs, two Fe-SODs, and one Mn-SOD, and they were divided into two subgroups according to phylogenetic analysis, gene structure, and conserved motifs. Cis-acting element analysis reveals various hormones and stress respond as cis-acting elements in the promoters of LcSODs. Gene expression analysis shows that most LcSOD genes were in response to abiotic stresses at the transcriptional level. These results help in clarifying the function of LcSOD genes under abiotic stresses, and provide potential targets for the improvement in abiotic stress tolerance in the endangered L. chinense.