Abstract
It has been hypothesized that nitrate (NO(3)(-)) nutrition might induce iron (Fe) deficiency chlorosis by inactivation of Fe in the leaf apoplast (H.U. Kosegarten, B. Hoffmann, K. Mengel [1999] Plant Physiol 121: 1069-1079). To test this hypothesis, sunflower (Helianthus annuus L. cv Farnkasol) plants were grown in nutrient solutions supplied with various nitrogen (N) forms (NO(3)(-), NH(4)(+) and NH(4)NO(3)), with or without pH control by using pH buffers [2-(N-morpholino)ethanesulfonic acid or 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid]. It was shown that high pH in the nutrient solution restricted uptake and shoot translocation of Fe independently of N form and, therefore, induced Fe deficiency chlorosis at low Fe supply [1 micro M ferric ethylenediaminedi(O-hydroxyphenylacetic acid)]. Root NO(3)(-) supply (up to 40 mM) did not affect the relative distribution of Fe between leaf apoplast and symplast at constant low external pH of the root medium. Although perfusion of high pH-buffered solution (7.0) into the leaf apoplast restricted (59)Fe uptake rate as compared with low apoplastic solution pH (5.0 and 6.0, respectively), loading of NO(3)(-) (6 mM) showed no effect on (59)Fe uptake by the symplast of leaf cells. However, high light intensity strongly increased (59)Fe uptake, independently of apoplastic pH or of the presence of NO(3)(-) in the apoplastic solution. Finally, there are no indications in the present study that NO(3)(-) supply to roots results in the postulated inactivation of Fe in the leaf apoplast. It is concluded that NO(3)(-) nutrition results in Fe deficiency chlorosis exclusively by inhibited Fe acquisition by roots due to high pH at the root surface.
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Claims 8
Claim · model-written summary
High pH in the nutrient solution restricted Fe uptake and shoot translocation in sunflower, independently of N form.
- Taxon
- sunflower
Helianthus annuuse1 - Material
- Farnkasole1
- Treatment
- high pH in the nutrient solutione2
- Outcome
- uptake and shoot translocation of Fee2
- Direction
- restrictede2
- Qualifier
- independently of N forme2
- Setting
- nutrient solutionse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“sunflower (Helianthus annuus L. cv Farnkasol) plants were grown in nutrient solutions supplied with various nitrogen (N) forms (NO(3)(-), NH(4)(+) and NH(4)NO(3)), with or without pH control by using pH buffers”
e2“It was shown that high pH in the nutrient solution restricted uptake and shoot translocation of Fe independently of N form and, therefore, induced Fe deficiency chlorosis at low Fe supply”
Claim · model-written summary
High pH in the nutrient solution induced Fe deficiency chlorosis in sunflower at low Fe supply.
- Taxon
- sunflowerHelianthus annuuse1
- Material
- Farnkasole1
- Treatment
- high pH in the nutrient solutione2
- Outcome
- Fe deficiency chlorosise2
- Direction
- inducede2
- Qualifier
- at low Fe supplye2
- Setting
- nutrient solutionse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“sunflower (Helianthus annuus L. cv Farnkasol) plants were grown in nutrient solutions supplied with various nitrogen (N) forms (NO(3)(-), NH(4)(+) and NH(4)NO(3)), with or without pH control by using pH buffers”
e2“It was shown that high pH in the nutrient solution restricted uptake and shoot translocation of Fe independently of N form and, therefore, induced Fe deficiency chlorosis at low Fe supply”
Claim · model-written summary
Root nitrate supply up to 40 mM did not affect the relative distribution of Fe between leaf apoplast and symplast in sunflower at constant low external pH.
- Taxon
- sunflowerHelianthus annuuse1
- Material
- Farnkasole1
- Treatment
- Root NO(3)(-) supply (up to 40 mM)e3
- Outcome
- relative distribution of Fe between leaf apoplast and symplaste3
- Direction
- did not affecte3
- Qualifier
- at constant low external pH of the root mediume3
- Setting
- nutrient solutionse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“sunflower (Helianthus annuus L. cv Farnkasol) plants were grown in nutrient solutions supplied with various nitrogen (N) forms (NO(3)(-), NH(4)(+) and NH(4)NO(3)), with or without pH control by using pH buffers”
e3“Root NO(3)(-) supply (up to 40 mM) did not affect the relative distribution of Fe between leaf apoplast and symplast at constant low external pH of the root medium”
Claim · model-written summary
Perfusion of high pH-buffered solution (7.0) into the leaf apoplast restricted 59Fe uptake rate in sunflower compared with low apoplastic pH (5.0 and 6.0).
- Taxon
- sunflowerHelianthus annuuse1
- Material
- Farnkasole1
- Organ / stage
- leaf apoplaste4
- Treatment
- perfusion of high pH-buffered solution (7.0) into the leaf apoplaste4
- Outcome
- (59)Fe uptake ratee4
- Direction
- restrictede4
- Comparator
- low apoplastic solution pH (5.0 and 6.0, respectively)e4
- Setting
- nutrient solutionse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“sunflower (Helianthus annuus L. cv Farnkasol) plants were grown in nutrient solutions supplied with various nitrogen (N) forms (NO(3)(-), NH(4)(+) and NH(4)NO(3)), with or without pH control by using pH buffers”
e4“Although perfusion of high pH-buffered solution (7.0) into the leaf apoplast restricted (59)Fe uptake rate as compared with low apoplastic solution pH (5.0 and 6.0, respectively)”
Claim · model-written summary
Loading of nitrate (6 mM) into the sunflower leaf apoplast showed no effect on 59Fe uptake by the leaf cell symplast.
- Taxon
- sunflowerHelianthus annuuse1
- Material
- Farnkasole1
- Organ / stage
- leaf cellse5
- Treatment
- loading of NO(3)(-) (6 mM)e5
- Outcome
- (59)Fe uptake by the symplast of leaf cellse5
- Direction
- showed no effecte5
- Setting
- nutrient solutionse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“sunflower (Helianthus annuus L. cv Farnkasol) plants were grown in nutrient solutions supplied with various nitrogen (N) forms (NO(3)(-), NH(4)(+) and NH(4)NO(3)), with or without pH control by using pH buffers”
e5“loading of NO(3)(-) (6 mM) showed no effect on (59)Fe uptake by the symplast of leaf cells”
Claim · model-written summary
High light intensity strongly increased 59Fe uptake in sunflower, independently of apoplastic pH or apoplastic nitrate.
- Taxon
- sunflowerHelianthus annuuse1
- Material
- Farnkasole1
- Treatment
- high light intensitye6
- Outcome
- (59)Fe uptakee6
- Direction
- strongly increasede6
- Qualifier
- independently of apoplastic pH or of the presence of NO(3)(-) in the apoplastic solutione6
- Setting
- nutrient solutionse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“sunflower (Helianthus annuus L. cv Farnkasol) plants were grown in nutrient solutions supplied with various nitrogen (N) forms (NO(3)(-), NH(4)(+) and NH(4)NO(3)), with or without pH control by using pH buffers”
e6“high light intensity strongly increased (59)Fe uptake, independently of apoplastic pH or of the presence of NO(3)(-) in the apoplastic solution”
Claim · model-written summary
The study found no indications that nitrate supply to sunflower roots inactivates Fe in the leaf apoplast.
- Taxon
- sunflowerHelianthus annuuse1
- Material
- Farnkasole1
- Treatment
- NO(3)(-) supply to rootse7
- Outcome
- inactivation of Fe in the leaf apoplaste7
- Setting
- nutrient solutionse1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“sunflower (Helianthus annuus L. cv Farnkasol) plants were grown in nutrient solutions supplied with various nitrogen (N) forms (NO(3)(-), NH(4)(+) and NH(4)NO(3)), with or without pH control by using pH buffers”
e7“there are no indications in the present study that NO(3)(-) supply to roots results in the postulated inactivation of Fe in the leaf apoplast”
Claim · model-written summary
Nitrate nutrition causes Fe deficiency chlorosis in sunflower exclusively by inhibited Fe acquisition by roots due to high pH at the root surface.
- Taxon
- sunflowerHelianthus annuuse1
- Material
- Farnkasole1
- Treatment
- NO(3)(-) nutritione7
- Outcome
- Fe deficiency chlorosise7
- Qualifier
- exclusively by inhibited Fe acquisition by roots due to high pH at the root surfacee7
- Setting
- nutrient solutionse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“sunflower (Helianthus annuus L. cv Farnkasol) plants were grown in nutrient solutions supplied with various nitrogen (N) forms (NO(3)(-), NH(4)(+) and NH(4)NO(3)), with or without pH control by using pH buffers”
e7“It is concluded that NO(3)(-) nutrition results in Fe deficiency chlorosis exclusively by inhibited Fe acquisition by roots due to high pH at the root surface”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.