Iron deficiency‐associated changes in the composition of the leaf apoplastic fluid from field‐grown pear (Pyrus communis L.) trees

Experiments have been carried out with field‐grown pear trees to investigate the effect of iron chlorosis on the composition of the leaf apoplast. Iron deficiency was associated with an increase in the leaf apoplastic pH from the control values of 5.5–5.9 to 6.5–6.6, as judged from direct pH measure...

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Bibliographic Details
Published in:Journal of experimental botany 2001-07, Vol.52 (360), p.1489-1498
Main Authors: López‐Millán, Ana Flor, Morales, Fermín, Abadía, Anunciación, Abadía, Javier
Format: Article
Language:English
Subjects:
5‐5′dithio‐bis‐2‐nitrobenzoic acid
5‐carboxy fluorescein
5‐CF
Anions
Anions - analysis
Apoplast
Ascorbic Acid - analysis
Biological and medical sciences
Biological Transport
Carbohydrates - analysis
Cations - analysis
Chlorophyll - analysis
Circles
citrate synthase
Citrates
Citric Acid - analysis
Dehydrogenases
DTNB
Enzymes - analysis
FC‐R
FDH
ferric‐chelate reductase
formate dehydrogenase
Fruit - physiology
Fundamental and applied biological sciences. Psychology
Hydrogen-Ion Concentration
Hypochromic anemia
ICDH
Iron
Iron - metabolism
Iron Chelating Agents - analysis
iron chlorosis
iron deficiency
isocitrate dehydrogenase
lactate dehydrogenase
LDH
Leaves
malate dehydrogenase
Malates - analysis
mass spectroscopy
MDH
Metabolism
Metabolism. Physicochemical requirements
Nucleotides - analysis
organic acids
PDC
pear
PEPC
phosphoenol pyruvate carboxylase
Physiological diseases. Varia
Phytopathology. Animal pests. Plant and forest protection
Plant Diseases
Plant Leaves - chemistry
Plant physiology
Plant physiology and development
Plants
plasma membrane
polyvinyl fluoride
portable Chl meter
PVDF
pyruvate decarboxylase
Regulation of Growth, Development and Whole Organism Physiology
Rosales - physiology
Solids
SPAD
Trees - physiology
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Summary:Experiments have been carried out with field‐grown pear trees to investigate the effect of iron chlorosis on the composition of the leaf apoplast. Iron deficiency was associated with an increase in the leaf apoplastic pH from the control values of 5.5–5.9 to 6.5–6.6, as judged from direct pH measurements in apoplastic fluid obtained by centrifugation and fluorescence of leaves incubated with 5‐CF. The major organic acids found in leaf apoplastic fluid of iron‐deficient and iron‐sufficient pear leaves were malate, citrate and ascorbate. The total concentration of organic acids was 2.9 mM in the controls and increased to 5.5 mM in Fe‐deficient leaves. The total apoplastic concentration of inorganic cations (Ca, K and Mg) increased with Fe deficiency from 15 to 20 mM. The total apoplastic concentration of inorganic anions (Cl−, NO3−, SO42− and HPO42−) did not change with Fe deficiency. Iron concentrations decreased from 4 to 1.6 μM with Fe deficiency. The major Fe species predicted to exist in the apoplast was [FeCitOH]−1 in both Fe‐sufficient and deficient leaves. Organic acids in whole leaf homogenates increased from 20 to 40 nmol m−2 with Fe deficiency. The accumulation of organic anions in the Fe‐deficient leaves does not appear to be associated to an increased C fixation in leaves, but rather it seems to be a consequence of C transport via xylem.
ISSN:0022-0957
1460-2431
DOI:10.1093/jexbot/52.360.1489