Abstract
BackgroundThe 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.ResultsHere 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.ConclusionSuch 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.
Highlights
The Ni hyperaccumulator Thlaspi goesingense is tolerant to Ni ≅ Zn, ≅ Co and slightly resistant to > Cd
The tolerance of T. goesingense to various metals including Ni, Co, Zn and Cd was investigated by measuring root growth compared to the non-tolerant relative A. thaliana Wassilewskija (WS) (Fig. 1) of plants grown on solidified MS medium containing Ni, Co, Zn or Cd
We observed that relative to A. thaliana the hyperaccumulator T. goesingense contained significantly less peroxidized lipids after growth in the presence of Ni, Co and Zn, no difference was observed after growth in the presence of Cd
Summary
The Ni hyperaccumulator Thlaspi goesingense is tolerant to Ni ≅ Zn, ≅ Co and slightly resistant to > Cd. The natural phenomenon of heavy metal tolerance in specialized hyperaccumulator plants has sparked the interests of plant physiologists, plant ecologists and evolutionary biologists for over 50 years [1]. Our research has focused on investigating the physiology of metal tolerance in metal hyperaccumulating plants, which are clearly hyper-toler-. Metal tolerance and metal hyperaccumulation are different but inter-related phenomena, and have been extensively reviewed [1,4,6,7]. In metal hyperaccumulators the genetic determinants of metal tolerance and accumulation segregate independently, confirming that different genes are responsible for these phenomena [8,9]. Transcriptional profiling has opened a window into the identity of the genetic changes driving metal hyperaccumulation, by uncovering sets of coordinated gene expression differences that likely control uptake, accumulation and tolerance in hyperaccumulatorsb [1012]
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