Iron deficiency-induced zinc uptake by bread wheat

摘要

The present study aimed to test the contribution of the iron (Fe) deficiency-induced uptake system to zinc (Zn) and copper (Cu) uptake by using bread wheat (Triticum aestivum cv. Bezostaja). For this purpose, two different uptake experiments, long-term and short-term, were set up in a nutrient solution culture under controlled growth chamber conditions. For the long-term experiment, wheat cv. plants were grown with different concentrations of Fe or Zn. Results show that there was an uptake system induced under Fe-limiting conditions which also contributed to Zn and Cu uptake. However, the Zn deficiency-induced uptake mechanism affected neither Fe nor Cu uptake by wheat. Short-term uptake experiments indicate that Fe deficiency-induced Zn2+ uptake was more enhanced than the absorption of Zn-phytosiderophore (PS) complexes. In addition, the Fe-deficient plants absorbed more Zn in comparison to those plants supplied with sufficient Fe. Similar tendencies in Zn uptake under Fe deficiency in both short- and long-term experiments suggest that there may be a specific Fe uptake system induced under Fe-limiting conditions for non-chelated metals in bread wheat. Moreover, this system also contributes to the transport of inorganic forms of some other metals, such as Zn and Cu. Although evidence is still needed involving the use of molecular biological techniques, it is hypothesized that IRT-like proteins are responsible for this uptake system. Moreover, the release of Fe deficiency-induced phytosiderophores and uptake of Fe(III)-phytosiderophore complexes may not be the only mechanisms involved in the adaptation of wheat to Fe-limiting conditions.