Higher plant metallothionein genes confer Cu resistance to yeast

Abstract

Metallothioneins (MTs) isolated from Arabidopsis thaliana, soybean and barley were expressed in a yeast cup1 mutant which is sensitive to a high concentration of Cu (25 μM) due to lack of the MT gene. Expression of plant MTs resulted in Cu resistance at varying levels depending on the constructs used. The transformant carrying the soybean MT gene acquired the highest level of Cu resistance (250 μM), followed by the Arabidopsis (50 μM) and the barley MT (25 μM) genes. The fact that the higher plant MT genes complemented the yeast cup1 mutation suggests that plant MT genes could be capable of playing a role in heavy metal detoxification in plants.