Organ-dependent responses of the african rice to short-term iron toxicity: Ferritin regulation and antioxidative responses

Abstract

Hydroponically grown African rice (Oryza glaberrima) was exposed for 72 h to a high Fe2+ concentration (500 mg dm-3) to identify the first steps of iron toxicity response in various organs. Iron accumulated in all plant parts analysed and had only a limited impact on absorption and translocation of other nutrients. The content of the iron-storage protein ferritin increased as a consequence of transcription stimulation or increase in mRNA stability and culminated after 48 h of treatment in laminae and to a lesser extent in sheaths but was not detected in roots. Although endogenous iron concentrations were similar in sheaths and laminae, superoxide dismutase activity was stimulated only in sheaths while ascorbate peroxidase activity increased mainly in laminae. It is concluded that both ferritin synthesis and antioxidative response may play a key role in the resistance of Oryza glaberrima to iron toxicity but that their relative importance are not the same in all organs. © 2007 Institute of Experimental Botany, ASCR.