Ferric reduction by<i>geum urbanum</i>: A kinetic study

Schmidt, Wolfgang; Janiesch, Peter

doi:10.1080/01904169109364262

Cited by 12 publications

(11 citation statements)

References 17 publications

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“…The apparent K , values we obtained were about 1 order of magnitude higher than those obtained by previous Bienfait et al [1983]), Lycopevsicon esculenfum (230 p~; Brüggemann et al [1990]), and Geuin uvbanum (87 p~; Schmidt and Janiesch [1991]). Our results were most similar to those of Susín et al (1996), who reported a K , of 514 PM in Fe-deficient Beta vulgaris.…”

Section: O Cu Deficiency and Fe Deficiency Lnduce The Same Ferric Rcontrasting

confidence: 52%

Induction of the Root Cell Plasma Membrane Ferric Reductase (An Exclusive Role for Fe and Cu)

1997

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Induction of ferric reductase activity in dicots and nongrass monocots is a well-recognized response to Fe deficiency. Recent evidence has shown that Cu deficiency also induces plasma membrane Fe reduction. In this study we investigated whether other nutrient deficiencies could also induce ferric reductase activity in roots of pea (Pisum sativum L. cv Sparkle) seedlings. Of the nutrient deficiencies tested (K, Mg, Ca, Mn, Zn, Fe, and Cu), only Cu and Fe deficiencies elicited a response. Cu deficiency induced an activity intermediate between Fe-deficient and control plant activities. To ascertain whether the same reductase is induced by Fe and Cu deficiency, concentration- and pH-dependent kinetics of root ferric reduction were compared in plants grown under control, -Fe, and -Cu conditions. Additionally, rhizosphere acidification, another process induced by Fe deficiency, was quantified in pea seedlings grown under the three regimes. Control, Fe-deficient, and Cu-deficient plants exhibited no major differences in pH optima or Km for the kinetics of ferric reduction. However, the Vmax for ferric reduction was dramatically influenced by plant nutrient status, increasing 16- to 38-fold under Fe deficiency and 1.5- to 4-fold under Cu deficiency, compared with that of control plants. These results are consistent with a model in which varying amounts of the same enzyme are deployed on the plasma membrane in response to plant Fe or Cu status. Rhizosphere acidification rates in the Cu-deficient plants were similarly intermediate between those of the control and Fe-deficient plants. These results suggest that Cu deficiency induces the same responses induced by Fe deficiency in peas.

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Section: O Cu Deficiency and Fe Deficiency Lnduce The Same Ferric Rcontrasting

confidence: 52%

Induction of the Root Cell Plasma Membrane Ferric Reductase (An Exclusive Role for Fe and Cu)

1997

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“…Decreases in the activity of the FC-R in Fe-deficient plants at high pH have been reported before for intact plants of peanut (Romheld and Marschner, 1983), apple (Ao et al, 1985), Ficus benjamina (Rosenfield et al, 1991), G. urbanum (Schmidt and Janiesch, 1991a), and A. thaliana (Moog et al, 1995). However, in most of these cases the pH www.plantphysiol.org on March 24, 2019 -Published by Downloaded from Copyright © 1996 American Society of Plant Biologists.…”

Section: Discussionmentioning

confidence: 82%

“…Data previously presented by Schmidt and Janiesch (1991a) indicated that the maximal rate of reduction by G.…”

Section: Discussionmentioning

confidence: 99%

“…The K , values were 221 and 233 ~L M in PM from control and Fe-deficient plants, respectively (Table IV). The only K , reported so far in the literature for the FCN-R in a strategy I plant was 208 p~ for G. urbanum (Schmidt and Janiesch, 1991a). The V,,, increased 3.5-fold with Fe deficiency, from 2649 to 9370 nmol Fe mg-' protein min-'.…”

Section: Enzymatic Characteristics Of the Fcn-r Activity In Pmmentioning

confidence: 99%

“…Vol. 11 O, 1996 Briiggemann andMoog, 1989) and subsequently in strategy I plants such as tomato (Buckhout et al, 1989;Briiggemann et al, 1990;Holden et al, 1991Holden et al, , 1992Valenti et al, 1991), bean (Schmidt and Janiesch, 1991b), Plantago (Schmidt et al, 1990), Geum urbanum (Schmidt and Janiesch, 1991a), Vigna unguiculata (Briiggemann et al, 1993), and Arabidopsis tkaliana (Moog et al, 1995). However, the PM from Fe-deficient plants usually exhibits FC-R activities biochemically similar to those of PM from control plants.…”

mentioning

confidence: 99%

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