Abstract: C2H2 type zinc-finger proteins (ZFPs) play important roles in abiotic stress response in plants. In this study, a novel C2H2 ZFP family gene, MsZAT10, from alfalfa (Medicago sativa), was cloned and characterized. The full length coding sequence (CDS) of MsZAT10 is 762 bp, and encodes a protein of 253 amino acids containing two conserved single C2H2 domains and a typical QALGGH conserved motif. Phylogenetic analysis showed that MsZAT10 shared sequence similarities of 76% with MtZAT10 [the closet homologous gene in Medicago truncatula (XP_003592502.1)]. The plant expression vector pCBM::MsZAT10 was constructed and inserted into tobacco by Agrobacturium-mediated transformation. Twenty-five positive transgenic lines were obtained, verified from a phosphinothricin screen and PCR identification. The MsZAT10 gene was expressed in transgenic lines confirmed by qRT-PCR analysis, and three transgenic lines were selected for further study. Transgenic tobacco plants showed higher tolerance and lower relative conductivity than those of wild type tobacco after exposure to a -4 ℃ temperature for 2 h. The tissue proline and soluble protein concentrations in transgenic tobacco were higher than those in wild type tobacco exposed to 0 ℃ for 5 h. In contrast, malondialdehyde levels were lower than those in wild type tobacco. After treatment with 300 mmol·L^-1 NaCl for 4 days, the leaf discs remained green in transgenic tobacco while the wild type tobacco turned chlorotic. These results indicated that overexpression of MsZAT10 enhanced plant tolerance to low temperature and salt stress in transgenic tobacco.

Key words: alfalfa, MsZAT10 gene, low temperature stress, salt stress, function