The pH Requirement for in Vivo Activity of the Iron-Deficiency-Induced "Turbo" Ferric Chelate Reductase (A Comparison of the Iron-Deficiency-Induced Iron Reductase Activities of Intact Plants and Isolated Plasma Membrane Fractions in Sugar Beet)

Susín, Santos A.; Abadı́a, Anunciación; González‐Reyes, José A.; Lucena, Juan J.; Abadı́a, Javier

doi:10.1104/pp.110.1.111

Cited by 111 publications

(72 citation statements)

References 34 publications

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“…The FC-R maximal values for leaf PM of control and Fedeficient sugar beet were 114 and 175 nmol Fe reduced mg Ϫ1 protein min Ϫ1 (González-Vallejo et al, 1999), values within the range found for other plant materials (Moog and Brü ggemann, 1994;Susín et al, 1996). If one assumes for PM an average protein content of 30% to 40% (mass/mass) and a density of 1.1 to 1.2 g mL Ϫ1 (Larsson and Moller, 1990), these FC-R values would be equivalent on a protoplast surface basis to approximately 5 to 10 and 9 to 15 ϫ 10 Ϫ12 nmol Fe reduced m Ϫ2 s Ϫ1 for control and Fedeficient sugar beet PM, respectively.…”

Section: Discussionmentioning

confidence: 91%

“…When these compounds were not included in the incubation medium, the resulting pellet obtained from the Fe-deficient leaves had a brownish color and contained few intact protoplasts. Both PVP and BSA are also necessary for the isolation of PMs from Fe-deficient sugar beet roots (Susín et al, 1996) and leaves (González-Vallejo et al, 1998, 1999. Inclusion of dithiothreitol (DTT) in the medium was crucial to obtaining good protoplast yields.…”

Section: Isolation and Purification Of Sugar Beet Protoplastsmentioning

confidence: 99%

“…The existence in the roots of dicotyledonous plants of an obligatory Fe reduction step from Fe(III) to Fe(II) prior to Fe root uptake was demonstrated first by Chaney et al (1972). The reduction of Fe(III) to Fe(II) is carried out by one or several specialized enzyme(s) located in the root cell plasma membrane (PM), the ferric-chelate reductase(s) (FC-R) (Bienfait, 1985(Bienfait, , 1988Cakmak et al, 1987;Rubinstein and Luster, 1993;Moog and Brü ggemann, 1994;Susín et al, 1996;Robinson et al, 1998Robinson et al, , 1999. Dicotyledonous plant species have the so-called strategy I (Marschner, 1995), that includes, among other mechanisms, the development of an increased capacity to reduce Fe.…”

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Iron Deficiency Decreases the Fe(III)-Chelate Reducing Activity of Leaf Protoplasts

et al. 2000

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The ferric-chelate reductase (FC-R) activity of mesophyll protoplasts isolated from Fe-sufficient (control) and Fe-deficient sugar beet (Beta vulgaris L.) leaves has been characterized. Measurements were made in an ionic environment similar to that in the apoplastic space of the sugar beet mesophyll cells. The FC-R activity of Fesufficient and Fe-deficient protoplasts was dependent on light. Fe deficiency decreased markedly the FC-R activity per protoplast surface unit. The optimal pH for the activity of the FC-R in mesophyll protoplasts was in the range 5.5 to 6.0, typical of the apoplastic space. Beyond pH 6.0, the activity of the FC-R in mesophyll protoplasts decreased markedly in both Fe-sufficient and Fedeficient protoplasts. These data suggest that both the intrinsic decrease in FC-R activity per protoplast surface and a possible shift in the pH of the apoplastic space could lead to the accumulation of physiologically inactive Fe pools in chlorotic leaves.

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Section: Discussionmentioning

confidence: 91%

Section: Isolation and Purification Of Sugar Beet Protoplastsmentioning

confidence: 99%

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confidence: 99%

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Iron Deficiency Decreases the Fe(III)-Chelate Reducing Activity of Leaf Protoplasts

et al. 2000

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“…1B), is enriched in flavins and has increased Fe(III)-reductase activity (Table I; Susín et al, 1993Susín et al, , 1996, and an adjacent white zone (WZ; approximately 5-10 mm from the apex), which does not have root hairs (Fig. 1A) and has much lower flavin concentrations and Fe(III)-reducing activities (Table I).…”

Section: Changes In Flavin Concentrations and Fc-r Activity In Roots mentioning

confidence: 99%

“…Strategy I also includes biochemical changes, such as a higher proton extrusion capacity (Brown, 1978), a release of reducing and/or chelating substances such as phenolics and flavins (Welkie and Miller, 1960;Susín et al, 1994), and the development of a two-step mechanism for iron uptake. In this mechanism iron is first reduced by a plasma membrane (PM)-bound ferric-chelate reductase (FC-R) enzyme (Moog and Brü ggemann, 1994;Susín et al, 1996;Robinson et al, 1999;Schmidt, 1999) and subsequently absorbed as Fe(II) (Chaney et al, 1972) by a specialized transporter (Eide et al, 1996;Fox and Guerinot, 1998).…”

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Responses of Sugar Beet Roots to Iron Deficiency. Changes in Carbon Assimilation and Oxygen Use

et al. 2000

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Different root parts with or without increased iron-reducing activities have been studied in iron-deficient and iron-sufficient control sugar beet (Beta vulgaris L. Monohil hybrid). The distal root parts of iron-deficient plants, 0 to 5 mm from the root apex, were capable to reduce Fe(III)-chelates and contained concentrations of flavins near 700 m, two characteristics absent in the 5 to 10 mm sections of iron-deficient plants and the whole root of iron-sufficient plants. Flavin-containing root tips had large pools of carboxylic acids and high activities of enzymes involved in organic acid metabolism. In iron-deficient yellow root tips there was a large increase in carbon fixation associated to an increase in phosphoenolpyruvate carboxylase activity. Part of this carbon was used, through an increase in mitochondrial activity, to increase the capacity to produce reducing power, whereas another part was exported via xylem. Root respiration was increased by iron deficiency. In sugar beet iron-deficient roots flavins would provide a suitable link between the increased capacity to produce reduced nucleotides and the plasma membrane associated ferric chelate reductase enzyme(s). Iron-deficient roots had a large oxygen consumption rate in the presence of cyanide and hydroxisalycilic acid, suggesting that the ferric chelate reductase enzyme is able to reduce oxygen in the absence of Fe(III)-chelates.

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Physiological responses of hawthorn (Crataegus persica Pojark.) and quince (Cydonia oblonga Mill.) rootstocks to bicarbonate‐induced iron deficiency in nutrient solution

Valipour

Khoshgoftarmanesh

Baninasab

2018

J. Plant Nutr. Soil Sci.

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Hawthorn (Crataegus persica Pojark.) is used as a quince (Cydonia oblonga Mill.) rootstock in order to reduce the severity of iron (Fe) chlorosis in quince orchards in alkaline calcareous soils in central Iran. This study was conducted to investigate physiological responses of Fe‐chlorosis resistant hawthorn and Fe chlorosis‐sensitive quince cultivars to Fe‐deficiency and different levels of HCO3 - (5, 10, 15, and 20 mM NaHCO3), in the presence or absence of 0.5 g CaCO3 L−1 in a CO2‐buffered pH 7.8 nutrient solution containing 50 μM Fe(III)‐EDTA. A separate set of two free‐bicarbonate controls containing deficient [5 μM Fe(III)‐EDTA] and sufficient [50 μM Fe(III)‐EDTA] Fe concentrations was also used. Chlorosis symptoms appeared on the rootstocks exposed to HCO3 - and in the 5 μM Fe(III)‐EDTA treatment. In response to HCO3 - ‐induced Fe deficiency, hawthorn roots released high amounts of H+ and phenolic compounds to the surrounding medium, while no such response was observed in quince. The higher resistance to bicarbonate of hawthorn was also related with a higher root activity of the ferric chelate reductase (FCR), associated to a higher Fe(OH)3 solubilization. Accordingly, hawthorn seedlings in the HCO3 - ‐induced Fe deficiency had higher leaf and root Fe concentrations in comparison to those in the direct Fe deficiency. The addition of CaCO3, in general, had no or small effect on the root release of H+ and phenolic compounds. The effectiveness of Fe‐deficiency resistance mechanisms described for hydroponically grown hawthorn have to be evaluated under soil conditions.

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The pH Requirement for in Vivo Activity of the Iron-Deficiency-Induced "Turbo" Ferric Chelate Reductase (A Comparison of the Iron-Deficiency-Induced Iron Reductase Activities of Intact Plants and Isolated Plasma Membrane Fractions in Sugar Beet)

Cited by 111 publications

References 34 publications

Iron Deficiency Decreases the Fe(III)-Chelate Reducing Activity of Leaf Protoplasts

Iron Deficiency Decreases the Fe(III)-Chelate Reducing Activity of Leaf Protoplasts

Responses of Sugar Beet Roots to Iron Deficiency. Changes in Carbon Assimilation and Oxygen Use

Physiological responses of hawthorn (Crataegus persica Pojark.) and quince (Cydonia oblonga Mill.) rootstocks to bicarbonate‐induced iron deficiency in nutrient solution

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