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Open Access Research article

Changes in the proteomic and metabolic profiles of Beta vulgaris root tips in response to iron deficiency and resupply

Rubén Rellán-Álvarez1, Sofía Andaluz14, Jorge Rodríguez-Celma1, Gert Wohlgemuth3, Graziano Zocchi2, Ana Álvarez-Fernández1, Oliver Fiehn3, Ana Flor López-Millán1 and Javier Abadía1*

Author Affiliations

1 Plant Nutrition Department, Aula Dei Experimental Station, CSIC, PO Box 13034, E-50080 Zaragoza, Spain

2 Dipartimento di Produzione Vegetale, Sez. Biochimica e Fisiologia delle Piante, Università di Milano, Via Celoria 2, I-20133 Milano, Italy

3 Genome Center, University of California Davis, CA 95616, USA

4 Current address: Zeu-Inmunotec, C/Bari, n° 25, Duplicado, E-50197, Zaragoza, Spain

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BMC Plant Biology 2010, 10:120  doi:10.1186/1471-2229-10-120

Published: 21 June 2010

Abstract

Background

Plants grown under iron deficiency show different morphological, biochemical and physiological changes. These changes include, among others, the elicitation of different strategies to improve the acquisition of Fe from the rhizosphere, the adjustment of Fe homeostasis processes and a reorganization of carbohydrate metabolism. The application of modern techniques that allow the simultaneous and untargeted analysis of multiple proteins and metabolites can provide insight into multiple processes taking place in plants under Fe deficiency. The objective of this study was to characterize the changes induced in the root tip proteome and metabolome of sugar beet plants in response to Fe deficiency and resupply.

Results

Root tip extract proteome maps were obtained by 2-D isoelectric focusing polyacrylamide gel electrophoresis, and approximately 140 spots were detected. Iron deficiency resulted in changes in the relative amounts of 61 polypeptides, and 22 of them were identified by mass spectrometry (MS). Metabolites in root tip extracts were analyzed by gas chromatography-MS, and more than 300 metabolites were resolved. Out of 77 identified metabolites, 26 changed significantly with Fe deficiency. Iron deficiency induced increases in the relative amounts of proteins and metabolites associated to glycolysis, tri-carboxylic acid cycle and anaerobic respiration, confirming previous studies. Furthermore, a protein not present in Fe-sufficient roots, dimethyl-8-ribityllumazine (DMRL) synthase, was present in high amounts in root tips from Fe-deficient sugar beet plants and gene transcript levels were higher in Fe-deficient root tips. Also, a marked increase in the relative amounts of the raffinose family of oligosaccharides (RFOs) was observed in Fe-deficient plants, and a further increase in these compounds occurred upon short term Fe resupply.

Conclusions

The increases in DMRL synthase and in RFO sugars were the major changes induced by Fe deficiency and resupply in root tips of sugar beet plants. Flavin synthesis could be involved in Fe uptake, whereas RFO sugars could be involved in the alleviation of oxidative stress, C trafficking or cell signalling. Our data also confirm the increase in proteins and metabolites related to carbohydrate metabolism and TCA cycle pathways.