Nicotiana sylvestris calcineurin B-like protein NsylCBL10 improves tolerance to high-salt stress through better maintenance of Na (+) balance. The calcineurin B-like (CBL) proteins represent a unique group of plant calcium sensors and play an important role in regulating the response of a plant cell to the stress. Although many studies have been made in Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa) and poplar (Populus trichocarpa), the characterization and elucidation of the functions of CBLs in tobacco have not yet been reported. In this study, NsylCBL10, a CBL gene showing higher similarities to other CBL10 genes, was cloned from Nicotiana sylvestris. NsylCBL10 is expressed in most of the tobacco tissues, and the protein targets to the plasma membrane specifically. Over-expression of NsylCBL10 enhanced the salt tolerance of Arabidopsis wild type plants greatly, and rescued the high-salt-sensitive phenotype of Arabidopsis cbl10 mutant. The analysis of ion content indicated that over-expressing NsylCBL10 in plants is able to maintain a lower Na(+)/K(+) ratio in roots and higher Na(+)/K(+) ratio in shoots, compared with cbl10 mutant. The results suggest that NsylCBL10 might play an important role in response to high salinity stress in N. sylvestris, by keeping a better ionic homeostasis to reduce the damage of toxic ion to the plant cell.
Keywords: Arabidopsis; CBL10; Nicotiana sylvestris; Salt stress; Salt tolerance.