Cloning And Expression Analysis Of SOD Gene In Eggplant(Solanum Melongena)

In this study,three SmSOD genes related to stress resistance were obtained using homology-based cloningmethod from eggplant,named as SmMnSOD,SmCu/ZnSOD and SmFeSOD,respectively.SmMnSOD contained a 687 bp open reading frame(ORF)encoding an amino acid sequence consisting of 228 amino acid residues with a molecular weight of about 25.63 kDa,which was homologous to pepper and tomato MnSOD gene sequences.The open reading frame of SmCu/ZnSOD was 459 bp,encoding a 15.25 kDa Cu/ZnSOD protein consisting of 152 amino acid residues.SmFeSOD contained an ORF of 720 bp and encodes a FeSOD protein consisting of 239 amino acid residues around 25.63 kDa.The results showed that SmCu/ZnSOD had 95% and 94% similarity to Cu/ZnSOD in potato and tomato respectively.The sequence homology of SmFeSOD with that of tobacco and tomato was 93% and 90%,respectively.The phylogenetic tree and the high-level structure model were constructed for three SmSOD proteins,and the relationship between the three kinds of SOD in eggplant and the similar SOD in other species was determined.Subcellular localization indicated that SmMnSOD protein located in mitochondria,SmCu/ZnSOD protein located in the nucleus and cytoplasm near the plasma membrane,and SmFeSOD protein located in the chloroplast.SmMnSOD,SmCu/ZnSOD and SmFeSOD were constitutively expressed in all six tissues of eggplant,but the expression level was different.SmMnSOD had the highest expression level in eggplant leaves,followed by roots and petals;The expression level in eggplant petals of SmCu/ZnSOD was significantly higher than that in other tissues;SmFeSOD had the highest expression level in eggplant leaves.The results showed that SmSOD played a positive role in the resistance of salt stress,low temperature stress and exogenous abscisic acid in eggplant.Under NaCl stress,the activity of total SOD was the highest,and the higher activity level was maintained longer,followed by low temperature and abscisic acid.PEG stress can slightly increase the SOD activity.Three SmSOD genes were independent of each other in response to different stress,and the overall stress resistance of eggplant was enhanced with the scavenging ability of ROS was improved by promoting the enzyme activity of SOD.The expression levels of SmMnSOD,SmCu/ZnSOD and SmFeSOD were all up-regulated rapidly under NaCl stress,while the expression of SmCu/ZnSOD and SmFeSOD could be up-regulated by low temperature stress.The expression of SmMnSOD and SmCu/ZnSOD increased at first and then increased,while SmFeSOD showed more fluctuation.After exogenous ABA treatment,the expression of SmMnSOD,SmCu/ZnSOD and SmFeSOD showed fluctuant changes.