SsDHN, a dehydrin protein from Suaeda salsa, enhances salt stress tolerance in transgenic tobacco plants

Dehydrins (DHNs) are late embryogenesis-abundant (LEA) proteins, which enhance abiotic stress tolerance in plants. However, little is known regarding the function of DHNs in Suaeda salsa L. (S. salsa), which can grow in saline soil. Here, we successfully cloned and functionally characterized a dehydrin gene from S. salsa, designated SsDHN. Sequence alignment analysis showed that SsDHN belongs to SKn-type DHNs and shares relatively high level of homology with Spinacia oleracea COR47-like (XP_021846321.1). Quantitative RT-PCR analysis indicated that SsDHN expression level increased significantly under salt stress. We also generated SsDHN-overexpressing transgenic tobacco lines and analyzed their salt stress response. Seeds of transgenic tobacco plants grown under a range of salt concentrations (100, 200, and 300 mM) showed significantly higher germination rates relative to wild-type seeds. Transgenic plants had longer root length, lower relative electrical conductivity (REC), lower malondialdehyde (MDA) content, higher proline (PRO) content, increased peroxidase (SOD) activity, and less damage to the chloroplast ultrastructure. Our results showed that the transgenic tobacco plant lines had improved salt resistance and osmotic adjustment, enhanced reactive oxygen species scavenging ability, maintenance of the K+/Na+ balance, and reduced chloroplast membrane damage. These results suggest that the SsDHN gene may be used for improving abiotic stress tolerance in economically important crops.