Iron (Fe) is an essential mineral nutrient which severely affects the growth, yield and nutritional quality of plants if not supplied in sufficient quantities. We here 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.

Background: Iron long distance transport in plants is underdocumented. Results: Iron is delivered to embryos as ferric complexes with citrate/malate. An ascorbate-mediated reduction step is further required to acquire iron. Conclusion: Ascorbate plays a key role for the chemical reduction and transport of Fe 2ϩ . Significance: The identification of iron ligands and the transport process is crucial to further understand how iron is distributed within the plant.

SummaryDescription of metal species in plant fluids such as xylem, phloem or related saps remains a complex challenge usually addressed either by liquid chromatography-mass spectrometry, X-ray analysis or computational prediction. To date, none of these techniques has achieved a complete and true picture of metal-containing species in plant fluids, especially for the least concentrated complexes. Here, we present a generic analytical methodology for a large-scale (> 10 metals, > 50 metal complexes) detection, identification and semiquantitative determination of metal complexes in the xylem and embryo sac liquid of the green pea, Pisum sativum.The procedure is based on direct injection using hydrophilic interaction chromatography with dual detection by elemental (inductively coupled plasma mass spectrometry) and molecular (high-resolution electrospray mass spectrometry) mass spectrometric detection.Numerous and novel complexes of iron(II), iron(III), copper(II), zinc, manganese, cobalt(II), cobalt(III), magnesium, calcium, nickel and molybdenum(IV) with several ligands including nicotianamine, citrate, malate, histidine, glutamine, aspartic acid, asparagine, phenylalanine and others are observed in pea fluids and discussed.This methodology provides a large inventory of various types of metal complexes, which is a significant asset for future biochemical and genetic studies into metal transport/homeostasis.