Abstract: GSH is the substrate that synthesizes PC, which chelates the heavy metals. Heavy metal-PC chelatins are subsequently transported from the cytosol to the vacuole and heavy metal detoxification is thus achieved. A plant-expressed plasmid with PC synthesase from Brassica juncea (BjPCS1) was constructed and transferred into tobacco. PCR and Northern blot indicated that BjPCS1 was integrated into the genome of tobacco and functioned properly. Physiological responses of the transformant to three heavy metals (200mmol/L CdCl2、400mmol/L ZnCl2、200mmol/L NiCl2) treatment, reflected by relative electronic conductivity (Rc/Rc’), chlorophyll content (Chla+b), content of dissolvent suga and MDA content, were better than those in the control plants. These results indicated that BjPCS1 transformation could improve the heavy metal tolerance of the transgenic tobaccos, especially Cd tolerance. Furthermore, the seedlings of offspring from BjPCS1 positive plants were tested for resistance to Cd. The results confirmed that the expression of BjPCS1 could enhance Cd tolerance of transgenic tobaccos. As its an important role in transgenic plants, BjPCS1 gene can work as a significant gene tool in the phytoremediation of heavy metal pollution.

Key words: Brassica juncea, BjPCS1, tobacco, heavy metal, resistance