Abstract:A gene encoding a late embryogenesis abundant(LEA) protein was isolated from seedling of Medicago ruthenica L..Sequence analysis revealed that it belongs to LEA_2 family according to the Pfam classification of LEA proteins,here named as MrLEA2(Medicago ruthenica late embryogenesis abundant protein 2).Semi-quantitative RT-PCR analysis showed that the expression level of MrLEA2 did not response to dehydration,high salinity,cold stress treatments and ABA application.A prokaryotic expression vector was constructed and MrLEA2 was successfully overexpressed in E.coli.In order to get the clues of the function that MrLEA2 plays in protecting cells against abiotic stresses,growth and survival of E.coli cells overexpressing MrLEA2 protein under abiotic stresses,including high salinity,heating and freezing,was appraised.Spot assays and colony counting investigation showed that overexpression of MrLEA2 increased the tolerance of E.coli to high salinity(0.5 mol/L NaCl or 0.5 mol/L KCl),heating(55 ℃) and freezing(-20 ℃) stresses.The results suggest that MrLEA2 plays a role in protection of cell against damage caused by salinity and temperature stress.