IRON MAN is a ubiquitous family of peptides that control iron transport in plants.

Iron (Fe) is an essential mineral nutrient that severely affects the growth, yield and nutritional quality of plants if not supplied in sufficient quantities. Here, we report that a short C-terminal amino-acid sequence consensus motif (IRON MAN; IMA) conserved across numerous, highly diverse peptides in angiosperms is essential for Fe uptake in plants. Overexpression of the IMA sequence in Arabidopsis induced Fe uptake genes in roots, causing accumulation of Fe and manganese in all plant parts including seeds. Silencing of all eight IMA genes harboured in the Arabidopsis genome abolished Fe uptake and caused severe chlorosis; increasing the Fe supply or expressing IMA1 restored the wild-type phenotype. IMA1 is predominantly expressed in the phloem, preferentially in leaves, and reciprocal grafting showed that IMA1 peptides in shoots positively regulate Fe uptake in roots. IMA homologues are highly responsive to the Fe status and functional when heterologously expressed across species. IMA constitutes a novel family of peptides that are critical for the acquisition and cellular homeostasis of Fe across land plants.

Characterization of Root Epidermal Cell Patterning and Differentiation in Arabidopsis.

The root epidermis of Arabidopsis thaliana has been established as a model system for elucidating the mechanisms which govern the spatial patterningAbstract and morphogenesis of plant cells. Investigations into root hairs focus on various aspects of the biology of epidermal cells, using methods specifically developed to dissect the biological question under study. Despite the large number of studies related to epidermal cell differentiation, a survey of methods to analyze the phenotypic readout resulting from environmental conditions or the genetic background of the plant has not been provided so far. This protocol describes how to analyze the spatial arrangement and morphologic characteristics of cells in the root epidermis based on whole mount roots or cross sections, using confocal, scanning electron and light microscopy. This comparison of methods aids in selecting the most suitable strategy to examine the differentiation of root epidermal cells at different developmental stages.