Effects of Fe deficiency on the protein profiles and lignin composition of stem tissues of Medicago truncatula in absence and presence of calcium carbonate

Authors: RODRÍGUEZ-CELMA, JORGE - Consejo Superior De Investigaciones Cientificas (CSIC); LATTANZIO, GIUSEPPE - Consejo Superior De Investigaciones Cientificas (CSIC); VILLARROYA, DIDO - Consejo Superior De Investigaciones Cientificas (CSIC); GUTIERREZ-CARBONELL, ELAIN - Consejo Superior De Investigaciones Cientificas (CSIC); CEBALLOS-LAITA, LAURA - Consejo Superior De Investigaciones Cientificas (CSIC); RENCORET, JORGE - Consejo Superior De Investigaciones Cientificas (CSIC); GUTIERREZ, ANA - Consejo Superior De Investigaciones Cientificas (CSIC); DEL RIO, JOSE - Consejo Superior De Investigaciones Cientificas (CSIC); Grusak, Michael; ABADIA, ANUNCIACION - Consejo Superior De Investigaciones Cientificas (CSIC); ABADIA, JAVIER - Consejo Superior De Investigaciones Cientificas (CSIC); LOPEZ-MILLAN, ANA-FLOR - Baylor College Of Medicine

Submitted to: Journal of Proteomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2016
Publication Date: 3/30/2016
Publication URL: https://handle.nal.usda.gov/10113/63179
Citation: Rodríguez-Celma, J., Lattanzio, G., Villarroya, D., Gutierrez-Carbonell, E., Ceballos-Laita, L., Rencoret, J., Gutierrez, A., Del Rio, J.C., Grusak, M.A., Abadia, A., Abadia, J., Lopez-Millan, A. 2016. Effects of Fe deficiency on the protein profiles and lignin composition of stem tissues of Medicago truncatula in absence and presence of calcium carbonate. Journal of Proteomics. 140:1–12.

Interpretive Summary: Iron deficient conditions in fields can significantly reduce crop yields, especially in soils with high levels of calcium carbonate where plants have difficulty absorbing iron. Plant stems are essential for the movement of iron and other minerals from the roots to the shoots, and the amount of minerals delivered to shoots has an impact on crop yield. Thus, the aim of this work was to study the effects of iron deficiency on the protein component of stems, in order to understand how stem function could be manipulated to improve yield under iron deficient conditions. We used the model legume, Medicago truncatula, to study protein extracts and cell wall components in stems. We identified individual proteins from stems of iron deficient plants grown in the presence or absence of calcium carbonate. Several changes in the abundance of specific proteins were seen. Our results indicated that iron deficiency by itself has a mild effect on the stem protein profile, whereas iron deficiency in the presence of calcium carbonate has a stronger impact and causes changes in more proteins in the stem. These changes included proteins involved in stress responses in plants, as well as proteins that helped to modify cell wall composition. These types of changes are likely to affect mineral transport and distribution to the leaves. Further analysis of specific proteins may allow us to better manage the delivery of essential minerals to leaves and seeds, especially when plants are challenged with iron deficiency stress.

Technical Abstract: Iron deficiency is a yield-limiting factor with major implications for crop production, especially in soils with high CaCO3. Because stems are essential for the delivery of nutrients to the shoots, the aim of this work was to study the effects of Fe deficiency on the stem proteome of Medicago truncatula. Two-dimensional electrophoresis separation of stem protein extracts resolved 276 consistent spots in the whole experiment. Iron deficiency in absence or presence of CaCO3 caused significant changes in relative abundance in 10 and 31 spots, respectively, and 80% of them were identified by mass spectrometry. Overall results indicate that Fe deficiency by itself has a mild effect on the stem proteome, whereas Fe deficiency in the presence of CaCO3 has a stronger impact and causes changes in a larger number of proteins, including increases in stress and protein metabolism related proteins not observed in the absence of CaCO3. Both treatments resulted in increases in cell wall related proteins, which were more intense in the presence of CaCO3. The increases induced by Fe-deficiency in the lignin per protein ratio and changes in the lignin monomer composition, assessed by pyrolysis-gas chromatography–mass spectrometry and microscopy, respectively, further support the existence of cell wall alterations. Biological significance: In spite of being essential for the delivery of nutrients to the shoots, our knowledge of stem responses to nutrient deficiencies is very limited. The present work applies 2-DE techniques to unravel the response of this understudied tissue to Fe deficiency. Proteomics data, complemented with mineral, lignin and microscopy analyses, indicate that stems respond to Fe deficiency by increasing stress and defense related proteins, probably in response of mineral and osmotic unbalances, and eliciting significant changes in cell wall composition. The changes observed are likely to ultimately affect solute transport and distribution to the leaves.