A relation between the ratios of phosphorus to iron and potassium to calcium in mustard leaves

Dekock, P. C.; Hall, A. D.; McDonald, Margaret J.

doi:10.1007/bf01377366

Cited by 40 publications

(19 citation statements)

References 26 publications

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“…As described in a previous commnnunication (10), mustard plants (Siniapis alba) were gron in nutrient culture containing three levels of iron (Fe1. Fe2, Fe3, resp.. 0.1, 0.5, and 2.5 ppnm Fe); four ratios of potassiunm to calciunm (K1, K.., K3, K4, resp.…”

Section: Methodsmentioning

confidence: 99%

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Interrelationships of Catalase, Peroxidase, Hematin, and Chlorophyll

et al. 1960

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Section: Methodsmentioning

confidence: 99%

“…Recent studlies on the iron nutrition of plants have showin that there is an interdependence among the elements phosphorus, iron, potassium, and calcium (10). Such relationships are strikingly apparent in variegated plants (9) and also in plants suffering from heavy nmetal toxicity (8) …”

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confidence: 99%

Interrelationships of Catalase, Peroxidase, Hematin, and Chlorophyll

et al. 1960

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“…Citrate accumulation, in response to iron deficiency, has been suggested to be caused by lowered levels of the iron-containing enzyme aconitase (1,8,31 Enzyme Assays. Tissue extracts were made by grinding the tissue (roots after washing with 0.5 mm CaSO4) with 50% (w/w) polyvinylpolypyrrolidone, washed sand and an extraction buffer at OC in a porcelain mortar.…”

Section: Introductionmentioning

confidence: 99%

Rhizosphere Acidification as a Response to Iron Deficiency in Bean Plants

Vos¹,

Lubberding²,

Bienfait³

1986

Plant Physiol.

122

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Iron deficiency in higher plants causes accumulation of salts of organic acids in the roots, the most characteristic being citrate. We show that citrate and malate accumulate in beans (Phaseolus vulgaris L. var Prelude), not because of a lack of the iron-containing enzyme aconitase (EC 4.2.13), but in close coupling to the extrusion of protons during rhizosphere acidification, one of the 'Fe-efficiency' reactions of dicotyledonous plants. When proton excretion is induced in roots of control bean plants by addition of fusicoccin, only malate, not citrate, is accumulated. We propose that iron deficiency induces production of organic acids in the roots, which in beans leads to both proton excretion and an increased capacity to reduce ferric chelates via the induced electron transfer system in the root epidermis cells.Plants growing under iron deficiency may employ different strategies to increase iron uptake: (a) dicotyledons and non-grass monocotyledons develop a strong ferric reduction activity at the root surface (2); moreover, they may acidify the rhizosphere by active proton extrusion (23); and (b) grasses excrete highly effective siderophores, which are structurally related to the cellular iron carrier nicotianamine (27). Both mono-and dicotyledons are known to accumulate organic acid salts, especially citrate, in roots (6,14,31) and leaves (10,26).Evidence has accumulated which shows that the ferric reduction activity in the roots of Fe-efficient dicotyledons resides in the plasma membrane of the root epidermis cells, where an enzyme system can transfer electrons from cytosolic NADPH to extracellular ferric chelates, with low substrate specificity (2). This enzyme system has not been found in grasses (19).We recently proposed that accumulated citrate, via the activities of aconitase and isocitrate dehydrogenase, is responsible for the strongly reduced redox poise of NADP in cells with high ferric reduction capacity (4). Citrate accumulation, in response to iron deficiency, has been suggested to be caused by lowered levels of the iron-containing enzyme aconitase (1,8,31 Enzyme Assays. Tissue extracts were made by grinding the tissue (roots after washing with 0.5 mm CaSO4) with 50% (w/w) polyvinylpolypyrrolidone, washed sand and an extraction buffer at OC in a porcelain mortar. The resulting brei was centrifuged at 1 lOOg for 5 min and the supernatant at 50.000g for 10 min. From the last supernatant 2.5 ml was brought over 4 ml Sephadex G-25 and the eluate was used for determination of enzyme activity. The extraction buffer for aconitase (EC 4.2.1.3) was 0.1 M Hepes, 10 mM tricarballylate, pH 7.5. The activity was determined in two ways: (a) by following the formation ofcis-aconitate from citrate at 240 nm (1 mM cis-aconitate: A240 = 3.55) (18). The reaction mixture contained, in a final volume of 500 ,ul, 0.1 M Hepes, 10 mM citrate, pH 7.5, and up to 100 Ml enzyme preparation. The reaction was started by addition of citrate; and (b)

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“…FeEDDH A generally is not considere d to be a good source of iron for corn and other grasses (Brown et al, 1960;Brown et al, 196lb The phosphor ous levels in shoots were sufficien tly greater for the ironinefficien t plants to be a possible factor in the iron deficienc y (Brown et al, 1959). Again, the calcium differen tial between the shoots of the two hybrids was indicativ e of iron deficienc y in the inefficien t one (DeKock et al, 1960).…”

Section: Resultsmentioning

confidence: 99%

“…Zinc, mangane se, phospho rus, and calcium levels were elevated in the iron-ine fficient plants. The latter two may be related to the fact that many of them were yellow with iron deficienc y (DeKock et al, 1960). ' Whethe r or not the fairly large zinc differen tial contribu ted to the iron inefi ficiency was tested in Experime nt 3.…”

Section: Resultsmentioning

confidence: 99%