Cyanobacteria MT gene SmtA enhance zinc tolerance in Arabidopsis.

Zinc is essential but toxic in excess. A bacterial metallothionein, SmtA from Synechococcus PCC 7942, has high affinity for Zn2+ and the intracellular exclusively handling of Zn2+. In this study, we report a functional analysis of SmtA in Arabidopsis thaliana and its response to zinc stress. After high zinc stress, the transgenic plants over-expressing SmtA showed higher survival rate than the wild type. We also found that over-expression of SmtA in Arabidopsis increased the activities of SOD and POD, and enhanced the tolerance to zinc stress. Together, our results indicate that SmtA may play an important role in the response to zinc stress in Arabidopsis.