Background: 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. Results: 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 μM 59Fe, 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 of 32P absorption essentially followed the rates of 59Fe uptake in Fe-deficient plants during Fe resupply, suggesting that P accumulation might be regulated by Fe uptake in maize plants. Conclusions: 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.

Transcriptional and physiological analyses of Fe deficiency response in maize reveal the presence of Strategy I components and Fe/P interactions

ZANIN, Laura
Primo
;
VENUTI, Silvia;TOMASI, Nicola;PINTON, Roberto
Ultimo
2017-01-01

Abstract

Background: 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. Results: 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 μM 59Fe, 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 of 32P absorption essentially followed the rates of 59Fe uptake in Fe-deficient plants during Fe resupply, suggesting that P accumulation might be regulated by Fe uptake in maize plants. Conclusions: 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.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11390/1107793
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