摘要
A new gene of metallothionein (MT) family was cloned from garlic (Allium sativum) seed-lings using RACE method and designated AsMT2b. The full length of AsMT2b cDNA was 520 bp encod-ing 80 amino acids. The deduced amino acids of AsMT2b showed that AsMT2b contained the char-acteristic structure of type 2 MT proteins, but the number and arrangement of the cysteine residues in the N- and C-terminal domains was different from other type 2 MT proteins. Semi-quantitative reverse transcriptase-PCR showed that transcript levels of AsMT2b were enhanced only in response to higher concentrations or longer incubation time of Cd. Such an expression pattern of AsMT2b greatly differed from that of other type 2 MT genes. Yeast cells transformed with this gene had improved resistance to Cd. AsMT2b overexpressing Arabidopsis showed stronger Cd tolerance and higher Cd accumulation compared with wild-type plants. These results sug-gest that AsMT2b should be useful in phytoremedia-tion of Cd-polluted soil in the future.
A new gene of metallothionein （MT） family was cloned from garlic （Allium sativum） seedlings using RACE method and designated AsMT2b. The full length of AsMT2b cDNA was 520 bp encoding 80 amino acids. The deduced amino acids of AsMT2b showed that AsMT2b contained the characteristic structure of type 2 MT proteins, but the number and arrangement of the cysteine residues in the N- and C-terminal domains was different from other type 2 MT proteins. Semi-quantitative reverse transcriptase-PCR showed that transcript levels of AsMT2b were enhanced only in response to higher concentrations or longer incubation time of Cd. Such an expression pattern of AsMT2b greatly differed from that of other type 2 MT genes. Yeast cells transformed with this gene had improved resistance to Cd. AsMT2b overexpressing Arabidopsis showed stronger Cd tolerance and higher Cd accumulation compared with wild-type plants. These results suggest that AsMT2b should be useful in phytoremediation of Cd-polluted soil in the future.
