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Title: Root responses of Medicago truncatula plants grown in two different iron deficiency conditions: changes in root protein profile and riboflavin biosynthesis

Author
item RODRIGUEZ-CELMA, JORGE - Consejo Superior De Investigaciones Cientificas (CSIC)
item LATTANZIO, GIUSEPPE - Consejo Superior De Investigaciones Cientificas (CSIC)
item Grusak, Michael
item ABADIA, ANUNCIACION - Consejo Superior De Investigaciones Cientificas (CSIC)
item ABADIA, JAVIER - Consejo Superior De Investigaciones Cientificas (CSIC)
item LOPEZ-MILLAN, ANA-FLOR - Consejo Superior De Investigaciones Cientificas (CSIC)

Submitted to: Journal of Proteome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2011
Publication Date: 5/6/2011
Citation: Rodriguez-Celma, J., Lattanzio, G., Grusak, M.A., Abadia, A., Abadia, J., Lopez-Millan, A. 2011. Root responses of Medicago truncatula plants grown in two different iron deficiency conditions: changes in root protein profile and riboflavin biosynthesis. Journal of Proteome Research. 10(5):2590-2601.

Interpretive Summary: Iron is an essential element for plants, being necessary for proper growth, development, and seed production. Iron is acquired from soils via processes functioning in roots, but the availability of iron in different soils can sometimes make it difficult for those roots to absorb enough iron to meet their needs. In particular, soils that are alkaline (high pH) and contain high levels of calcium carbonate (also known as calcareous soils) are poor sources of iron. Crops growing in these soils are often iron deficient and poorly productive. As a means to improve the ability of crops to gain iron when challenged with iron-limited soils, we need to understand how it is that some plants can respond to these conditions in beneficial ways, thereby allowing them to meet their iron nutrition needs. In this study, we investigated various biochemical and molecular characteristics of the roots of a plant from the legume family (bean and pea family), using plants treated with iron-limited conditions. We learned that the roots of this plant could synthesize and release compounds that increased the levels of available iron in the soil. The plants also could change their internal biochemical properties to help them function more effectively with less iron. The identification of these changes and the identification of some of the genes responsible for them are providing tools and insights to help us develop new crops with improved abilities for acquiring iron.

Technical Abstract: Iron deficiency is a yield-limiting factor with major implications for field crop production in one-third of the world's agricultural areas, especially those with high soil CaCO3. A two-dimensional gel electrophoresis proteomic approach was combined with a study on the riboflavin synthesis pathway, including qPCR and riboflavin determination, to investigate Fe-deficiency responses in Medicago truncatula plants grown with and without CaCO3. Iron deficiency caused a de novo accumulation of DMRLs and GTPcII; proteins involved in riboflavin biosynthesis, as well as marked increases in root riboflavin concentrations and in the expression of four genes from the riboflavin biosynthetic pathway. Two novel changes were the increased accumulation of proteins related to N recycling and protein catabolism. Other identified changes were consistent with previously shown increases in glycolysis, TCA-cycle, and stress-related processes. All effects were more marked in the presence of CaCO3. The riboflavin synthesis pathway was up-regulated (at the genomic, proteomic and metabolomic levels) under both Fe deficiency treatments, especially in the presence of CaCO3. Results also indicate that N recycling occurs in M. truncatula upon Fe deficiency, possibly constituting an additional anaplerotic N and C source for the synthesis of secondary metabolites, carboxylates, and others.