IMPACT OF IRON-DEFICIENCY AND IRON RE-SUPPLY DURING THE EARLY STAGES OF VEGETATIVE DEVELOPMENT IN MAIZE (ZEA-MAYS L.)

The consequences of iron deficiency and iron re-supply were evaluated during the early stages of growth and development of young maize plant lets grown hydroponically in the absence of iron, Various parameters, such as fresh and dry weights, and the concentration of chlorophylls, iron, copper, manganese, calcium, magnesium and potassium in leaves, w ere measured at various times during the first 15 d of culture, Ten-da y-old maize plantlets grown without iron displayed severe alterations, with a 50% decrease in iron and chlorophyll concentrations in leaves, and serious impairments in mitochondria and chloroplast ultrastructur e. In contrast, neither leaf nor root growth, nor other mineral concen trations other than iron were significantly affected at this stage of development, In an attempt to characterize proteins potentially involv ed in iron nutrition or the adaptative response to iron starvation, co mparative 2D-gel electrophoretic analysis of polypeptides was carried out on soluble and membrane fractions prepared from leaves and roots o f iron-deficient and iron-sufficient 10-d-old maize plantlets, Two pol ypeptides (11 and 17 kDa, pI of about 6.8) from the microsomal fractio n of leaves were found to be repressed under iron-deficient conditions , Some other polypeptides were found to be induced in microsomal fract ions either from roots or leaves, Significant variations in the concen tration of most of these polypeptides were observed from one experimen t to another, It can be concluded from this study that, at this early stage of maize vegetative growth and development, molecular variations induced by iron deficiency do not affect major house-keeping proteins , but probably affect very specific events depending on low abundance proteins.