Iron deficiency responses in roots of kiwi

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Abstract
Many dicotyledonous species respond to iron (Fe) deficiency by morphological and physiological changes at root level, which are usually defined as Strategy I. Particularly, these latter modifications include a higher acidification of the external medium and the induction of a high root Fe reductase activity. The aim of this work was to investigate the response of kiwi (Actinidia deliciosa cv. Hayward) plants, which often exhibit Fe chlorosis in the field, to Fe deficiency. Actinidia kept for two weeks in nutrient solution without Fe showed visual deficiency symptoms (leaf chlorosis). Moreover, upon prolonged micronutrient shortage shoot, and to a lesser extent, root dry weight accumulation was greatly impaired. Roots of Fe‐deficient Actinidia showed an increased capacity of net proton extrusion and higher ferric ethylenediaminetetraacetate [Fe(III)EDTA] reductase activity as compared to plants grown in the presence of 10 μM Fe(III)EDTA. Localization of the increased acidification and reductase capacity by means of agar‐technique revealed that these activities are both present in the sub‐apical region of the roots. Re‐supply of Fe after two weeks partially reversed the tendency of the roots to acidify the nutrient solution and to reduce Fe(III)EDTA.