Uptake of Zn and Fe by wheat (Triticum aestivum var. Greina) and transfer to the grains in the presence of chelating agents (ethylenediaminedisuccinic acid and ethylenediaminetetraacetic acid).
A way to decrease iron and zinc deficiency in humans is to biofortify foods by increasing the bioavailable contents in these elements. The aim of this work was to study if chelating agents could be used to increase the capture of Fe and Zn by wheat grains. Zn and/or Fe in combination with the chelating agents ethylenediaminedisuccinic acid (EDDS) or ethylenediaminetetraacetic acid (EDTA) were added at various times (i.e., at flower head formation, anthesis, and postanthesis) to spring wheat ( Triticum aestivum var. Greina) grown in nutrient solution. Treatments lasted for 2 weeks, and the plants were harvested at grain maturity. The shoots of treated plants accumulated higher Zn and/or Fe concentrations than untreated plants, depending on the treatment. The plants also accumulated significant concentrations of EDDS or EDTA in their shoots. Elevated Zn and Fe concentrations in the shoots did in most cases not lead to significantly higher Zn and Fe concentrations in the grains. The grains of plants treated with EDDS during flower head formation accumulated elevated Fe and Zn concentrations but at the cost of a reduction in yield. The control plants transferred higher percentages of Fe and Zn from the shoot into the grain than the treated plants. This indicates that EDTA and EDDS inhibited in most cases the translocation of Fe and Zn from the shoots into the grains. The amounts of EDDS and EDTA found in the grains of treated plants were very small. This indicates that there was little transfer of the chelates into the symplast and that the apoplastic pathway, which is important for the transport of chelants into the shoots, is efficiently blocked between shoots and seeds.
Nowack
B
B
Institute of Terrestrial Ecosystems, ETH Zurich, Universitaetstrasse 16, 8092 Zurich, Switzerland. nowack@empa.ch
Schwyzer
I
I
Schulin
R
R
D002614:Chelating Agents / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D005029:Ethylenediamines / Q000494:pharmacology; D005527:Food, Fortified; D007501:Iron / Q000032:analysis / Q000378:metabolism*; D018520:Plant Shoots / Q000737:chemistry; D012639:Seeds / Q000737:chemistry / Q000378:metabolism*; D013386:Succinates / Q000494:pharmacology; D014908:Triticum / Q000254:growth & development / Q000378:metabolism*; D015032:Zinc / Q000032:analysis / Q000378:metabolism*
D002614:Chelating Agents; D005029:Ethylenediamines; D013386:Succinates; C041447:N,N'-ethylenediamine disuccinic acid; D004492:Edetic Acid; D007501:Iron; D015032:Zinc