Molecular Mechanisms of Stress Tolerance of Superoxide Dismutase Gene Family in Populus euphratica

In this study, we employed conventional bioinformatics methods to analyze the differences of current status, homology, protein three-dimensional structure and the expression regulation in response to salt stress among SOD subfamily members of Populus euphratica. The findings indicated that there are 3 SOD gene subfamilies in the genome of P. euphratica, including Cu, Zn−SOD (CSD), Mn−SOD (MSD), and Fe−SOD (FSD). The genome of P. euphratica contains 7, 3 and 2 SOD subfamily members, respectively. Among which FSD3 has been pseudogenized and lost its function. FSD1 gene is highly expressed in leaf tissue of P. euphratica. MSD subfamily genes were highly expressed in roots, leaves and callus of P. euphratica and P. trichocarpa. MSD1 gene, as the only gene that is continuously upregulated under salt stress. Three amino acid mutations of MSD1(187K−T and 202H−N) and MSD2(97R−N) could be lead to enhanced interactions between the subunits of the tetramer, making the 2 MSDs of P. euphratica have higher protein stability, which is beneficial for protein accumulation.