ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Effect of different Fe(III) compounds on photosynthetic electron transport in spinach chloroplasts and on iron accumulation in maize plants

Katarína Kráľová, Elena Masarovičová, František Šeršeň, and Iveta Ondrejkovičová

Institute of Chemistry, Faculty of Natural Sciences, Comenius University, SK-842 15 Bratislava, Slovakia

E-mail: kralova@fns.uniba.sk

Received: 26 October 2007  Revised: 21 January 2008  Accepted: 23 January 2008

Abstract: Synthesis and spectral characteristics of [Fe(nia)₃Cl₃] and [Fe(nia)₃(H₂O)₂](ClO₄)₃ are described. The effect of these compounds as well as of FeCl₃·6H₂O on photosynthetic electron transport in spinach chloroplasts was investigated using EPR spectroscopy. It was found that due to the interaction of these compounds with tyrosine radicals situated at the 161^st position in D₁ (Tyr_Z) and D₂ (Tyr_D) proteins located at the donor side of photosystem (PS) II, electron transport between the photosynthetic centres PS II and PS I was interrupted. In addition, the treatment with [Fe(nia)₃(H₂O)₂](ClO₄)₃ resulted in a release of Mn(II) from the oxygen evolving complex situated on the donor side of PS II. Moreover, the effect of the Fe(III) compounds studied on some production characteristics of hydroponically cultivated maize plants and on Fe accumulation in plant organs was investigated. In general, the production characteristic most inhibited by the presence of Fe(III) compounds was the leaf dry mass and [Fe(nia)₃(H₂O)₂](ClO₄)₃ was found to be the most effective compound. The highest Fe amount was accumulated in the roots, and the leaves treated with Fe(III) compounds contained more Fe than the stems. The treatment with FeCl₃·6H₂O caused the most effective translocation of Fe into the shoots. Comparing the effect of nicotinamide complexes, [Fe(nia)₃(H₂O)₂](ClO₄)₃ was found to facilitate the translocation of Fe into the shoots more effectively than [Fe(nia)₃Cl₃]. This could be connected with the different structure of these complexes. [Fe(nia)₃(H₂O)₂](ClO₄)₃ has ionic structure and, in addition, coordinated H₂O molecules can be easily substituted by other ligands.

Keywords: EPR spectroscopy - translocation - iron-nicotinamide complexes - maize plants - bioaccumulation

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-008-0036-9

Chemical Papers 62 (4) 358–363 (2008)