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Scholarly Works (5 results)

  • Article
  • Peer Reviewed
The Proceedings of the International Plant Nutrition Colloquium XVI (2009)

Immobilization and accumulation of Fe in physiologically inactive forms somewhere in the leaf has been suggested to be associated to chlorosis in Fe-deficient leaves. The localization of elements at tissue level is essential to understand the plant processes involved in inorganic ion homeostasis. In this study we have used LT-SEM-EDX microanalysis to investigate the spatial distribution of Fe at tissue level in peach leaves under Fe-sufficient and Fe-deficient status. Chlorotic leaves from field peach trees showed a preferential localization of Fe in spongy parenchyma.

    Cover page: Elemental microanalysis in leaf transversal sections of peach by SEM/EDXA: Influence of iron nutritional status
    • Article
    • Peer Reviewed
    The Proceedings of the International Plant Nutrition Colloquium XVI (2009)

    The effects of high Zn concentrations in growth and photosynthetic parameters of sugar beet (Beta vulgaris L.) plants grown in hydroponics were investigated. Zinc toxicity (100 and 300 µM) resulted in large reductions in biomass accumulation (>50%) and photosynthetic rates (40-50%). It was known that high Zn concentrations usually lead to decreases in net photosynthesis, but the effects of excess Zn on each of the possible factors limiting photosynthesis, including photochemistry, stomatal conductance and mesophyll conductance, had not been studied in detail until now. Leaf photochemistry was not affected by Zn, and reduced photosynthesis was due mostly to marked decreases in stomatal conductance, whereas mesophyll conductance decreased to a lower extent. Stomata were study using scanning electron microscopy (SEM) and large structural differences were observed in stomatal frequency, size and shape between 300 µM Zn and control plants. In high Zn plants stomatal density was lower than in the controls, and stomata were smaller and had a more rounded shape than those present in control plants. The presence of these morphological changes could be associated to the reductions in photosynthetic rates under excess Zn.

      Cover page: Stomatal conductance is the main limitation to photosynthesis in sugar beet plants treated with Zn excess
      • Article
      • Peer Reviewed
      The Proceedings of the International Plant Nutrition Colloquium XVI (2009)

      A comprehensive analysis of the proteomic and metabolomic changes occurring in sugar beet root tips under Fe deficiency and Fe resupply has been carried out. Root tip samples were taken from Fe-sufficient (+Fe), Fe-deficient (-Fe) and Fe-resupplied plants at 24 and 72 h (in the latter case in two different root zones). Proteome maps were obtained using two-dimensional IEF-SDS PAGE. More than 140 spots were detected in gels from root tips of Fe-deficient and control plants, and Fe deficiency induced significant changes in the intensity of a large number of these polypeptides, many of them related to carbohydrate catabolism. A protein not present in Fe-sufficient roots, DMRL synthase, was present in high amounts in root tips from Fe-deficient sugar beet plants and was also found to be transcriptionally regulated by Fe status. Seventy-seven metabolites were identified by GC-MS. Statistical analysis using univariate, breakdown one-way ANOVA, and multivariate, supervised partial least square was carried out. Score scatter plots using the first 2 components showed a good separation of the different treatments, with metabolites in the 72 h Fe-resupplied samples being close those obtained in Fe-sufficient conditions. An activation of TCA cycle components was observed in Fe-deficient root tips when compared to the controls. An increase in the amount of the raffinose series of oligosaccharides (RSOs), including raffinose, galactinol, lacto-bionic acid and myo-inositol was observed in root tips of Fe-deficient and 24 h Fe-resupplied plants when compared to the controls.

        Cover page: CHANGES IN THE PROTEOMIC AND METABOLOMIC PROFILES OF BETA VULGARIS ROOT TIPS IN RESPONSE TO IRON DEFICIENCY AND RESUPPLY
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (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.
        • 1 supplemental file
        Cover page: Changes in the proteomic and metabolic profiles of Beta vulgaris root tips in response to iron deficiency and resupply
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2013)
        Iron homeostasis is an important process for flower development and plant fertility. The role of plastids in these processes has been shown to be essential. To document the relationships between plastid iron homeostasis and flower biology further, a global study (transcriptome, proteome, metabolome, and hormone analysis) was performed of Arabidopsis flowers from wild-type and triple atfer1-3-4 ferritin mutant plants grown under iron-sufficient or excess conditions. Some major modifications in specific functional categories were consistently observed at these three omic levels, although no significant overlaps of specific transcripts and proteins were detected. These modifications concerned redox reactions and oxidative stress, as well as amino acid and protein catabolism, this latter point being exemplified by an almost 10-fold increase in urea concentration of atfer1-3-4 flowers from plants grown under iron excess conditions. The mutant background caused alterations in Fe-haem redox proteins located in membranes and in hormone-responsive proteins. Specific effects of excess Fe in the mutant included further changes in these categories, supporting the idea that the mutant is facing a more intense Fe/redox stress than the wild type. The mutation and/or excess Fe had a strong impact at the membrane level, as denoted by the changes in the transporter and lipid metabolism categories. In spite of the large number of genes and proteins responsive to hormones found to be regulated in this study, changes in the hormonal balance were restricted to cytokinins, especially in the mutant plants grown under Fe excess conditions.
          Cover page: Iron-dependent modifications of the flower transcriptome, proteome, metabolome, and hormonal content in an Arabidopsis ferritin mutant
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