1 .pdf copia del póster original presentado por los autores en el Simposio Internacional. Se acompaña de 1 .pdf copia del resumen oficial.The synthetic ferric chelate based on the molecule ethylenediamine-N,N’-bis(hydroxyphenylacetic)acid, commonly named as Fe(III)-o,oEDDHA, is one of the most efficient fertilizers used to correct Fe deficiency in crops growing in calcareous soils. Iron(III)-o,oEDDHA has two diastereoisomers, the meso form and the racemic mixture, which are present in approximately equal amounts in commercial Fe-chelate fertilizer formulations. In previous studies, evidence was presented that Strategy I plants (tomato, pepper [1], bean [2, 3] and cucumber [4]) take up Fe preferentially from the meso chelate form when compared to the racemic one. The aim of the present work was to determine the differences in Fe uptake and distribution inside the plant between both Fe(III)-o,oEDDHA isomers, using the Strategy I species sugar beet, stable Fe isotopes (54Fe and 57Fe) and inductively coupled plasma-mass spectrometry (ICP-MS). Both Fe(III)-o,oEDDHA isomers were separated by selective Mg precipitation, then Fe was removed and the resulting o,oEDDHA acid isomers were chelated with 54Fe or 57Fe. Iron-deficient sugar beet plants were treated for 24 hours with i) 30 µM racemic 57Fe(III)-o,oEDDHA : 30 µM meso 54Fe(III)-o,oEDDHA or ii) 30 µM racemic 54Fe(III)-o,oEDDHA : 30 µM meso 57Fe(III)-o,oEDDHA. Roots, xylem sap, old and young leaves were sampled, and the 56Fe, 54Fe and 57Fe contents in all plant materials and nutrient solutions were determined by isotope dilution analysis and ICP-MS. Plants took up Fe preferentially from the meso Fe(III)-o,oEDDHA isomer, independently of the Fe stable isotope used. However, the distribution of the Fe supplied by both isomers inside the plant was different, since the Fe isotope supplied by the meso isomer accumulated preferentially in roots, whereas plant shoot materials (xylem and leaves) had similar contents of the Fe isotopes provided by both isomers. Therefore, it can be concluded that both isomers were equally effective in allocating Fe in aerial plant parts, whereas the meso isomer was more effective in allocating Fe in roots.This study was supported by the Spanish Ministry of Science and Education (projects AGL2006-1416 and AGL2007-61948, co-financed with FEDER), the European Commission (EU 6th Framework Integrated Project ISAFRUIT), and the Aragón Government (group A03).Peer reviewe
