Different nitrogen forms differentially affect Cd uptake and accumulation in dwarf Polish wheat (Triticum polonicum...

This study investigated the effects of different nitrogen (N) forms on Cadmium (Cd) uptake and accumulation in dwarf Polish wheat (DPW) seedlings, which were grown under Cd stress with N-Null, NH₄⁺-N, NO₃^--N and NH₄⁺-N + NO₃^--N. We measured plant growth and determined Cd uptake, translocation, accumulation, subcellular distribution and chemical forms in the roots and shoots of DPW seedlings. We also analyzed saccharide concentrations, and the transcript levels of genes encoding metal transporters in the roots of DPW seedlings. In the absence of NO₃^--N, addition of NH₄⁺-N reduced roots Cd concentration, F_CW (Cd in cell wall), F_S (Cd in soluble fraction) and F_E (inorganic Cd) concentrations, and induced the expression of four genes encoding metal transporters in roots, while it promoted Cd translocation to shoots. In the presence of NO₃^--N, addition of NH₄⁺-N increased roots Cd concentration, F_CW and F_W concentrations, and induced the expression of 22 genes encoding metal transporters in roots. Regardless of NH₄⁺-N level, addition of NO₃^--N increased roots Cd concentration, F_CW, F_S, F_W (water-soluble Cd), F_NaCl (pectates and protein Cd), F_HAc (undissolved Cd phosphate) and lactose concentrations, and also induced the expression of genes encoding metal transporters in roots. Overall, NH₄⁺-N differently regulated Cd uptake and accumulation in DPW seedlings in the absence or presence of NO₃^--N, while NO₃^--N greatly increased Cd uptake and accumulation in the presence of NH₄⁺-N compared to the absence of NH₄⁺-N. These patterns of Cd alteration likely arose due to different N forms altering Cd subcellular distribution and chemical forms, lactose concentration and the expression of metal transporter genes.