| Summary: | Sheepgrass is a perennial native grass species in China, and it can tolerate high levels of salt stress with an aggressive and vigorous rhizome system. Many salt-stress-responsive genes have been identified in sheepgrass. In this study, we report the cloning and characterization of a novel salt-induced gene, <i>LcSAIN3</i> (<i>Leymus chinensis</i> salt-induced 3), from sheepgrass. Expression analysis confirmed that <i>LcSAIN3</i> was induced by PEG, ABA, and salt treatments, and the expression of <i>LcSAIN3</i> was significantly increased in salt-tolerant germplasms under salt treatment. Subcellular localization analysis indicated that the GFP-LcSAIN3 protein was mainly localized in the chloroplasts. The heterologous expression of <i>LcSAIN3</i> in Arabidopsis increased the seed germination rate of transgenic plants under salt, ABA, and mannitol treatments. The seedling survival rate, plant height, and fresh weight of the transgenic plants were higher than those of WT plants under salt stress. The overexpression of <i>LcSAIN3</i> caused a relatively high accumulation of free proline, enhanced SOD activity, and led to the upregulation of several stress-responsive genes such as <i>AtRD26</i>, <i>AtRD29B</i>, <i>AtSOS1,</i> and <i>AtP5CS1</i>. These results suggest that <i>LcSAIN3</i> could be a potential target for molecular breeding to improve plants’ salt tolerance.
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