Effectiveness of Phytosiderophore in Absorption and Translocation of ⁵⁹Iron in Barley in the Presence of Plant-Borne, Synthetic, and Microbial Chelators

ABSTRACT

The mechanisms of iron (Fe) absorption and translocation in plants have received much study because they are the key processes in the supply of Fe to plants. The objective of this research was to study the effectiveness of phytosiderophore (PS) in the absorption and translocation of ⁵⁹Fe in Fe-deficient barley (Hordeum vulgare L. cv. ‘Minorimugi’) plants in the presence of plant-borne, synthetic, or microbial chelators. Plants grown under Fe-deficient conditions in a phytotron at pH 5.5 for 7–18 d were fed with Fe³⁺ (10 μ M labeled with ⁵⁹Fe) in the presence of 10 μ M of different chelators with or without 10 μ M PS for 4 h starting at 2 p.m. (6 h after the onset of light period). The absorption and translocation of ⁵⁹Fe in plants treated with PS and Fe^{3 +} were increased relative to plants fed solely with Fe^{3 +} (control). There was no effect found on absorption and translocation of ⁵⁹Fe in plants treated with EDTA or p-coumarate relative to the control, but a differential increase was observed in ⁵⁹Fe absorption and translocation in plants treated with EDTA or p-coumarate in the presence of PS. In comparison with the control, a decrease in ⁵⁹Fe absorption and translocation was observed in plants treated with HEDTA or EDDHA or FOB, but this decrease was avoided in plants treated with HEDTA or EDDHA or FOB in the presence of PS. The enhancement of ⁵⁹Fe absorption and translocation in plants treated with citrate, and the highest ⁵⁹Fe absorption and translocation in plants treated with citrate and PS, indicated that citrate had an additive effect on Fe absorption and translocation in plants. Our results showed that PS effectively played a role in Fe absorption and translocation in plants in the presence of other chelators. Plants treated with any chelators had lower extracellular ⁵⁹Fe in the roots compared with the control.

Keywords:

• citrate
• FOB
• p-coumarate
• PS
• synthetic chelators

ACKNOWLEDGMENTS

The senior author thanks the Japan Society for the Promotion of Science (JSPS) for providing him with the postdoctoral fellowship to perform this work.