title: Transcriptional and physiological analyses of Fe deficiency response in maize reveal the presence of Strategy I components and Fe/P interactions.
abstract: Under limited iron (Fe) availability maize, a Strategy II plant, improves Fe acquisition through the release of phytosiderophores (PS) into the rhizosphere and the subsequent uptake of Fe-PS complexes into root cells. Occurrence of Strategy-I-like components and interactions with phosphorous (P) nutrition has been hypothesized based on molecular and physiological studies in grasses.
  
  
  
  In this report transcriptomic analysis (NimbleGen microarray) of Fe deficiency response revealed that maize roots modulated the expression levels of 724 genes (508 up- and 216 down-regulated, respectively). As expected, roots of Fe-deficient maize plants overexpressed genes involved in the synthesis and release of 2'-deoxymugineic acid (the main PS released by maize roots). A strong modulation of genes involved in regulatory aspects, Fe translocation, root morphological modification, primary metabolic pathways and hormonal metabolism was induced by the nutritional stress. Genes encoding transporters for Fe2+(ZmNRAMP1) and P (ZmPHT1;7 and ZmPHO1) were also up-regulated under Fe deficiency. Fe-deficient maize plants accumulated higher amounts of P than the Fe-sufficient ones, both in roots and shoots. The supply of 1 μM59Fe, as soluble (Fe-Citrate and Fe-PS) or sparingly soluble (Ferrihydrite) sources to deficient plants, caused a rapid down-regulation of genes coding for PS and Fe(III)-PS transport, as well as of ZmNRAMP1 and ZmPHT1;7. Levels of32P absorption essentially followed the rates of59Fe uptake in Fe-deficient plants during Fe resupply, suggesting that P accumulation might be regulated by Fe uptake in maize plants.
  
  
  
  The transcriptional response to Fe-deficiency in maize roots confirmed the modulation of known genes involved in the Strategy II and revealed the presence of Strategy I components usually described in dicots. Moreover, data here presented provide evidence of a close relationship between two essential nutrients for plants, Fe and P, and highlight a key role played by Fe and P transporters to preserve the homeostasis of these two nutrients in maize plants.
authors.affiliation: Dipartimento di Scienze Agroalimentari, Ambientali e Animali, University of Udine, via delle Scienze 206, I-33100, Udine, Italy. laura.zanin@uniud.it.
authors.forename: Laura
authors.identifier: 0000-0002-3840-9843
authors.initials: L
authors.lastname: Zanin
authors.affiliation: Dipartimento di Scienze Agroalimentari, Ambientali e Animali, University of Udine, via delle Scienze 206, I-33100, Udine, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Venuti
authors.affiliation: Dipartimento di Biotecnologie, University of Verona, Ca' Vignal 1- Strada Le Grazie 15, I-37134, Verona, Italy.
authors.forename: Anita
authors.initials: A
authors.lastname: Zamboni
authors.affiliation: Dipartimento di Biotecnologie, University of Verona, Ca' Vignal 1- Strada Le Grazie 15, I-37134, Verona, Italy.
authors.forename: Zeno
authors.initials: Z
authors.lastname: Varanini
authors.affiliation: Dipartimento di Scienze Agroalimentari, Ambientali e Animali, University of Udine, via delle Scienze 206, I-33100, Udine, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Tomasi
authors.affiliation: Dipartimento di Scienze Agroalimentari, Ambientali e Animali, University of Udine, via delle Scienze 206, I-33100, Udine, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Pinton
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D000090463:Iron Deficiencies; D010641:Phenotype; D010710:Phosphates / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D012995:Solubility; D059467:Transcriptome; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism*
chemical_list: D005290:Ferric Compounds; D010710:Phosphates; D007501:Iron
keywords: Fe-source; Gene expression; Iron; Mineral nutrition; NRAMP; Phosphate transporter; Phosphorous uptake; Root acquisition; Strategy II; Zea mays