Effects of the interactions between nickel and other trace metals on their accumulation in the hyperaccumulator Noccaea caerulescens

Abstract

Nickel hyperaccumulators are a group of particular plant species which possess high efficient Ni uptake transport systems in their roots, the mechanisms of which however are far from being understood. Study on the interactions between nickel and other trace metals during root absorption process can provide insights into the Ni uptake patterns. Therefore, this work used model hyperaccumulator species Noccaea caerulescens to comprehensively assess the interaction between Ni and other trace metals (Zn, Fe, Mn, Cu and Co) during the root uptake process. Plants were grown in nutrient solutions containing different concentrations of Ni, Zn, Fe and Co, and the metal concentrations in roots and shoots were determined. Furthermore, the gene expression levels of Zn and Fe transporters were determined by quantitative real-time reverse transcriptase PCR. Results showed that Ni uptake could be severely suppressed by the presence of Zn or Co, while greatly stimulated by Zn or Fe deficiency. Iron uptake could be also stimulated by Ni exposure. In addition, the expression levels of the Zn transporter ZIP10 and the Fe transporter IRT1 were increased after Ni exposure. It could be concluded that the great competition between Ni and the non-essential element Co indicates that Ni uptake is mainly controlled by non-specific transporters. Nickel may be mainly taken up via Zn transporters, while Fe transporters also play a role for Ni absorption.