Nitrate N influences the accumulations and subcellular distributions of Cd and Zn to mediate the Cd/Zn interactions in dwarf Polish Wheat (Triticum polonicum L.) seedlings

Nitrate (NO3–) assimilation and transport play important roles in Cd transport. Transcript profiling indicated that several NO3− metabolism-related genes were involved in Cd/Zn interactions in roots of dwarf Polish Wheat (DPW). In this study, the effects of NO3− on Cd and Zn accumulations and subcellular distributions in DPW under Cd, Zn, and Cd + Zn applications with lack or supply of NO3− were investigated. Compared with lack of NO3–, supply of NO3− enhanced the Cd accumulation and the NO3− uptake in roots under Cd application; it reduced the Zn accumulation and the NO3− uptake in roots under Zn application; it did not affect the Cd accumulation and the NO3− uptake, but reduced the Zn accumulation in roots under Cd + Zn application. Supply of NO3− increased the Cd concentration in soluble fraction (including vacuole) to enhance the Cd capacity in roots under Cd application; it reduced the Zn concentration in soluble fraction under Zn application, and in all fractions under Cd + Zn application. Under lack or supply of NO3–, application of Zn inhibited the Cd accumulation in roots with reducing the Cd concentration of soluble fraction, but promoted in shoots with increasing the Cd concentration of organelle fraction; application of Cd promoted the Zn accumulation in roots, but inhibited in shoots (except of supply of NO3–). These results indicated that NO3− influenced the subcellular distributions of Cd and Zn to affect their accumulations, although the affections were different.