Abstract: Calmodulin, the predominant calcium receptor, is one of the best-characterized calcium sensors in eukaryotes which regulates diverse cellular functions by modulating the activity of a variety of enzymes and proteins. Research workers have evidences suggesting Ca2+ and calmodulin are involved in various environment stimulation reaction. By differential screen, we isolated a positive clone in the T.caerulescens cDNA library induced in response to Cd2+. The result of cDNA sequence analysis showed that the positive clone shared more than 92 % homologies for nucleotide sequences with CaM2 gene from Arabidopsis thanliana, named TcCaM2. The TcCaM2 gene consists of 447 nucleotides and encodes 149 amino acids, and it shares more than 83 % homologies for nucleotide sequences and 95 % for encoding amino acid sequences as compared with those of calmodulin genes of other plants. A yeast-expressed plasmid with TcCaM2 was constructed and transferred into heavy metal sensitive yeast mutant cells. Further study about the growth patterns of TcCaM2 -expressed yeast indicated that over expression of TcCaM2 improved Co2+、Ni2+ resistance and increased Cd2+ hypersensitivity in the yeast cells. As an important role in the T.caerulescens’s response to heavy metal, TcCaM2 can work as a significant gene tool in the phytoremediation of heavy metal pollution.

Key words: TcCaM2, heavy metal, calmodulin(CaM), Thlaspi caerulescens, yeast