A Zostera marina manganese superoxide dismutase gene involved in the responses to temperature stress

• Identified and characterized ZmMnSOD gene from Zostera marina
• Biochemical analysis of rZmMnSOD protein was performed.
• Decreased transcript of ZmMnSOD was observed under heat stress.
• Enzymatic activity of rZmMnSOD protein initially increased and then decreased under heat stress.

Superoxide dismutase (SOD) is an essential enzyme playing a pivotal role in the protection mechanism against oxidative stress by reducing superoxide radicals. In the present study, the full-length cDNA sequence of manganese superoxide dismutase was identified from Zostera marina (ZmMnSOD) via raid amplification of cDNA ends (RACE) technique and expressed sequence tags (ESTs) analysis. The open reading frame (ORF) encoded a polypeptide of 254 amino acid residues, which shared 69%–77% similarity with previous identified SODs. Analysis of the deduced amino acid revealed conserved features, including functional domains, signature motifs and metal binding sites. Phylogenetic analysis revealed that ZmMnSOD was closer to the SODs from angiosperm than those from other organisms. The mRNA expression level of ZmMnSOD at different temperatures was investigated using real-time PCR and it was significantly up-regulated from 5 °C to 15 °C, and then dramatically down-regulated. The recombinant ZmMnSOD protein was purified and exhibited Mn2 + ions dependency specific enzymatic activity and strong antioxidant activity over a wide temperature range. All these results indicate that ZmMnSOD is an authentic member of the plant SOD family and may play important roles in minimizing the effect of oxidative damage in Z. marina against temperature stress and affect the adaptability of Z. marina to global warming.