Cloning and characterization of type 2 metallothionein-like gene from a wetland plant, Typha latifolia

A type 2 metallothionein-like (MT-like) gene, tyMT, was cloned from Cattail (Typha latifolia), a wetland plant with constitutional tolerance to heavy metals. The gene encoded a deduced peptide of 79 aa residues, containing the cysteine-rich domains, typical of plant type 2 MT-like proteins which included the presence of C-C, C-X-C, and C-X-X-C (X are other amino acids other than cysteine) motifs at amino-terminus and carboxy-terminus. Southern blot analysis suggested that the tyMT gene belongs to a multi-gene family. Northern blot hybridization results showed that the transcripts of the tyMT gene in root and shoot were differently regulated by heavy metals, such as Cu2+ and Cd2+, providing new information for plant MT-like genes. When expressing the tyMT in copper sensitive MT-deficient strain of yeast, it restored the yeast's metal tolerance. Moreover, when the tyMTgene was introduced into Arabidopsis thaliana, the transgenic plants showed an increased tolerance to heavy metals, such as Cu2+ and Cd2+. These results confirm that the tyMT gene is involved in heavy metal tolerance of T latifolia. (C) 2004 Elsevier Ireland Ltd. All rights reserved.