In an article titled,, “Cloning and characterization of a gene encoding a Mn-containing superoxide dismutase in Eutrema halophilum the authors deduced that the polypeptide had a putative Mn-binding site. Recombinant ThMSD protein was expressed in Escherichia coli and characterized. Thestudy furtherconfirmed that ThMSD is an Mn-SOD. Real-time PCR revealed that ThMSD was expressed in roots, rosette leaves, stems, stem leaves, flowers, and siliques. ThMSD mRNA reached the highest content in roots and its content increased when plants were treated with NaCl, ABA, and subjected to drought. ThMSD was transferred intoArabidopsis and the stress tolerance properties of trans- genic lines were assayed. The seeds of transgenic lines exhibited significantly higher germination rate under 100 and 150 mM NaCl than the wild type. The root growth of transgenic lines was affected less obviously than the wild type under 100 mM NaCl. The above results indicate that ThMSD plays an important role in the tolerance ofE. halophilum to environmental stresses, especially that ofNaCl.