Abstract
In screening of activation-tagged mutants for salt tolerance at cellular levels in Arabidopsis thaliana, we identified 18 potential mutants. In one of them, salt tolerant callus 8 (stc8), a gene for basic helix-loop-helix transcription factor (bHLH106) was found activated regardless of NaCl stress. bHLH106 was highly expressed in calli and salt-inducible. Green fluorescent protein (GFP) fused with bHLH106 has shown that it is located in the nucleus. A knock-out line of bHLH106 was more sensitive to different concentrations of NaCl than the wild-type. The back-transformation has resulted in calli over-expressing bHLH106, which were tolerant to different levels of NaCl stress compared with calli transformed with a blank vector. The over-expression of bHLH106 in differentiated plants has also exhibited tolerance to 100 and 125 mM NaCl. These results indicate that bHLH106 plays an important role in regulation of salt stress in Arabidopsis.
