Effect of tris(3-hydroxy-4-pyridinonate) iron(III) complexes on iron uptake and storage in soybean (Glycine max L.)

Iron deficiency chlorosis (IDC) is a serious environmental problem affecting the growth of several crops in the world. The application of synthetic Fe(III) chelates is still one of the most common measures to correct IDC and the search for more effective Fe chelates remains an important issue. Herein, we propose a tris(3-hydroxy-4-pyridinonate) iron(III) complex, Fe(mpp)3, as an IDC corrector. Different morphological, biochemical and molecular parameters were assessed as a first step towards understanding its mode of action, compared with that of the commercial fertilizer FeEDDHA. Plants treated with the pyridinone iron(III) complexes were significantly greener and had increased biomass. The total Fe content was measured using ICP-OES and plants treated with pyridinone complexes accumulated about 50% more Fe than those treated with the commercial chelate. In particular, plants supplied with compound Fe(mpp)3 were able to translocate iron from the roots to the shoots and did not elicit the expression of the Fe-stress related genes FRO2 and IRT1. These results suggest that 3,4-HPO iron(III) chelates could be a potential new class of plant fertilizing agents.