Understanding salt tolerance mechanisms is important for the increase of crop yields, and so, several screening approaches were developed to identify plant genes which are involved in salt tolerance of plants. Here, we transformed the Arabidopsis cDNA library into a salt-sensitive calcineurin (CaN)-deficient (cnbD) yeast mutant and isolated the colonies which can suppress salt-sensitive phenotype of cnbD mutant. Through this functional complementation screen, a total of 34 colonies functionally suppressed the salt-sensitive phenotype of cnbD yeast cells, and sequencing analysis revealed that these are 9 genes, including CaS, AtSUMO1 and AtHB-12. Among these genes, the ectopic expression of CaS gene increased salt tolerance in yeast, and CaS transcript was up-regulated under high salinity conditions. CaS-antisense transgenic plants showed reduced root elongation under 100 mM NaCl treatment compared to the wild type plant, which survived under 150 mM NaCl treatment, whereas CaS-antisense transgenic plant leaves turned yellow under 150 mM NaCl treatment. These results indicate that the expression of CaS gene is important for stress tolerance in yeast and plants.

Calcium-binding proteins, like calcineurin B-like (CBL) proteins, represent important roles in plant calcium signaling. Calcium signals mediate a multitude of plant responses to external stimuli and regulate a wide range of physiological processes including pathogens, abiotic stresses and hormones. These proteins form a complex network with their target kinases being the CBL-interacting protein kinases (CIPKs). CBL genes play vital roles in multiple abiotic stress response pathways whereas some of these are more specifically involved in mediating ABA signaling. In this study, we collected 17 CBL genes designated as B. rapa CBL (BrCBL) from the Brassica database and analyzed the sequences. In comparison analysis, these genes showed high homology with published CBL genes of other species. An organ specific expression of these genes was observed in different organs of chinese cabbage plants. In addition, six BrCBL genes showed responsive expression after cold and drought stress treatments at certain time courses. All these data revealed that these CBL genes might be useful resources in developing abiotic stresses resistance Brassica.