Research article

The metal tolerance profile of Thlaspi goesingense is mimicked in Arabidopsis thaliana heterologously expressing serine acetyl-transferase

John L Freeman^1,2 and David E Salt¹

¹Center for Plant Environmental Stress Physiology, Purdue University, Horticulture and Landscape Architecture Department. West Lafayette, Indiana 47907, USA

²Biology Department, Colorado State University, Program in Molecular Plant Biology, Fort Collins, Colorado 80523, USA

author email corresponding author email

BMC Plant Biology 2007, 7:63doi:10.1186/1471-2229-7-63

Published:	28 November 2007

Abstract

Background

The Ni hyperaccumulator Thlaspi goesingense is tolerant to Ni ≅ Zn, ≅ Co and slightly resistant to > Cd. We previously observed that elevated glutathione, driven by constitutive activation of serine acetyltransferase (SAT), plays a role in the Ni tolerance of T. goesingense.

Results

Here we show that the elevated shoot concentration of glutathione, previously shown to cause elevated Ni tolerance in Arabidopsis thaliana heterologously expressing T. goesingense mitochondrial serine acetyltransferase (SATm), also causes tolerance to Co and Zn while slightly enhancing resistance to Cd. The level of tolerance afforded to each metal is ranked Ni ≅ Co, > Zn > Cd. The Ni ≅ Co, > Zn tolerances are positively correlated with both the accumulation of glutathione (GSH) and the ability to resist the oxidative damage induced by these different metals. Based on the relative concentrations of each metal used a relatively low level of resistance to Cd was observed in both T. goesingense and TgSATm expressing lines and Cd resistance was least correlated to GSH accumulation.

Conclusion

Such data supports the conclusion that elevated glutathione levels, driven by constitutively enhanced SAT activity in the hyperaccumulator T. goesingense, plays an important role in the Ni, Co and Zn tolerance of this and other Thlaspi species. The hyper-activation of S assimilation through SAT is an excellent strategy for engineering enhanced metal tolerance in transgenic plants potentially used for phytoremediation.