Tobacco phytochelatin synthase (NtPCS1) plays important roles in cadmium and arsenic tolerance and in early plant development in tobacco

Phytochelatin synthase (PCS) catalyzes the synthesis of phytochelatins, which are involved in heavy metal detoxification in plants and other living organisms. Previously, we cloned a PCS1 gene from tobacco (Nicotiana tabacum) and showed that its expression in yeast (Saccharomyces cerevisiae) resulted in increased cadmium (Cd) tolerance and Cd accumulation (Kim et al., J Plant Biol 48: 440-447, 2005). To examine the role of NtPCS1 in tobacco, we generated transgenic tobacco lines over-expressing NtPCS1 in the sense or antisense direction. Compared with other PCS1-expressing plants, NtPCS1-expressing tobacco exhibited a unique phenotype: increased tolerance to cadmium and arsenite, but no change in cadmium and arsenic accumulation. In addition, the antisense-NtPCS1 tobacco lines showed growth retardation in the early stage, suggesting that phytochelatin also plays a role in plant development. These results demonstrate that NtPCS1 plays important roles in metal(loid) tolerance as well as in growth and development in tobacco.