Background: As a high-quality legume forage, Medicago sativa is restricted by various abiotic stresses during its growth and development. Proteins with domains of unknown function (DUF) are reportedly involved in abiotic stress tolerance in plants. However, the biological functions of DUF-containing proteins in alfalfa (Medicago sativa L.) related to environmental stress remain poorly understood. 
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Methods: We reported previously a novel stress-responsive gene, MsDUF, from alfalfa that was up-regulated under drought stress. In this study, MsDUF, a 210 amino acid protein containing a DUF4228 domain, was identified in alfalfa. Furthermore, MsDUF-overexpressing tobacco plants were constructed to explore the functions of MsDUF in plant resistance to abiotic stress. 
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Result: Compared with wild-type tobacco, relative water content, osmoregulator (proline and soluble sugars) content and superoxide dismutase activity were elevated and malondialdehyde content was decreased in leaves of MsDUF-overexpressing plants under drought and salt stress (p&lt;0.05). The results indicate that MsDUF plays a vital role in responses to drought and salt stress in tobacco. Thus, this protein could be used to improve drought and salt resistance of tobacco and other crops.

Molecular Cloning and Functional Analysis of MsDUF from Alfalfa (Medicago sativa L.)