Characterising calcium (Ca) distribution in leaves of Brassica rapa at low and high Ca-supply, using energy-dispersive X-ray spectroscopy (EDS) with Cryo-Scanning electron microscope (CryoSEM)

• Rios, J. J. ^[1] ; Lochlainn, S. Ó. ^[1] ; J. Devonshire ^[3] ; Hammond, J. P. ^[1] ; Graham, N. S. ^[1] ; King, G. J. ^[2] ; Kurup, S. ^[3] ; White. P. J. ^[4] ; Broadley, M. R. ^[1]
  1. [1] University of Nottingham

     University of Nottingham

     Reino Unido

     
  2. [2] Southern Cross University

     Southern Cross University

     Australia

     
  3. [3] Rothamsted Research Institute
  4. [4] Scottish Crop Research Institute

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• Localización: SEFV 2011: programa de sesiones y resúmenes de conferencias plenarias e invitadas / coord. por Vicent Arbona Mengual, Rosa María Pérez Clemente, María Fernanda López Climent, Aurelio Gómez Cadenas, 2011, ISBN 978-84-8021-805-4, pág. 38
• Idioma: inglés
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• Resumen

  • Horticultural Brassica crops are an important source of dietary minerals for humans, includingcalcium (Ca). There is considerable natural genetic variation in whole-leaf Ca concentrationamong horticultural Brassica. The aim of this study was to determine the distribution of Cawithin leaves of a model Brassica species, using energy-dispersive X-ray spectroscopy (EDS)together with cryo-scanning electron microscopy (CryoSEM). Brassica rapa R-o-18 plants weregrown in compost under controlled conditions for 15 d. Pre-sowing, either 3 mM (low) or 24mM (high) CaCl2 was added to the compost as the main treatment factor. Two sections of leaftissue (7 mm x 5 mm) were cut, one from the apex and one from the base of a fully-expandedleaf, from two plants per treatment. Sections were mounted on a stub, frozen, and transferred toa cryo chamber at -180ºC under vacuum. Subsequently, sections were fractured, etched toremove contaminating ice and coated with Au. Processed sections were mounted on the SEMstage (JEOL LV6360, Jeol, Tokyo, Japan) at -160ºC; parameters were set for EDS using theOXFORD INCA 2000 microanalysis system (Oxford Instruments, High Wycombe, UK). Foreach section, 10 spectra from each of four cell types (adaxial epidermis, palisade mesophyll,spongy mesophyll and abaxial epidermis) were collected (i.e. 320 spectra in total). The resultsshow there was a greater concentration of Ca inside palisade mesophyll cells compared to theother cells types. The leaf apex accumulated more Ca than the leaf base. There was a generalincrease in leaf Ca concentration under high Ca supply, but no differences were observed in therelative leaf-distribution of Ca between plants grown under low and high Ca supply. Since thereis a large population of mutants available in Brassica rapa R-o-18 (designed for TargetingInduced Local Lesion IN Genomes, TILLING, analysis), it will be possible to use thisphenotyping approach to characterize the role of specific genes in controlling Ca homeostasis atthe level of the leaf.