Impact of iron deficiency and iron re‐supply during the early stages of vegetative development in maize (Zea mays L.)

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Abstract
The consequences of iron deficiency and iron re‐supply were evaluated during the early stages of growth and development of young maize plantlets 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, were measured at various times during the first 15 d of culture. Ten‐day‐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 ultrastructure. In contrast, neither leaf nor root growth, nor other mineral concentrations other than iron were significantly affected at this stage of development. In an attempt to characterize proteins potentially involved in iron nutrition or the adaptative response to iron starvation, comparative 2D‐gel electrophoretic analysis of polypeptides was carried out on soluble and membrane fractions prepared from leaves and roots of iron‐deficient and iron‐sufficient 10‐d‐old maize plantlets. Two polypeptides (11 and 17 kDa, pI of about 6.8) from the microsomal fraction of leaves were found to be repressed under iron‐deficient conditions. Some other polypeptides were found to he induced in microsomal fractions either from roots or leaves. Significant variations in the concentration of most of these polypeptides were observed from one experiment 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.