Expression of the seed-specific metallothionein mt4a in plant vegetative tissues increases Cu and Zn tolerance

The aim of this work was to express the seed-specific metallothionein 4 (mt4a) gene in Arabidopsis thaliana vegetative tissues, in order to study its effect on plant Cu and Zn tolerance and accumulation. In that way, mt4a gene was expressed under the regulation of the 35S CaMV promoter in A. thaliana plants. Expression of mt4a gene in vegetative tissues at different developmental stages conferred increased plant tolerance towards Cu and Zn, as concluded from root length measurement and shoot biomass determination. However, our results suggest that expression of mt4a gene in vegetative tissues of A. thaliana plants leads to a slight increase in plant Cu accumulation and do not increase Zn content in the plants.