Functional Screening of Plant Genes Suppressed Salt Sensitive Phenotype of Calcineurin Deficient Mutant through Yeast Complementation Analysis

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 (cnbΔ) yeast mutant and isolated the colonies which can suppress salt-sensitive phenotype of cnbΔ mutant. Through this functional complementation screen, a total of 34 colonies functionally suppressed the salt-sensitive phenotype of cnbΔ yeast cells, and sequencing analysis revealed that these are 9 genes, including CaS, AtSUMO1and AtHB-12. Among these genes, the ectopic expression of CaSgene increased salt tolerance in yeast, and CaStranscript 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.