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 7
Claim · model-written summary
High pH in the nutrient solution restricted Fe uptake and shoot translocation in sunflower, independently of N form, inducing Fe deficiency chlorosis at low Fe supply.
- Taxon
- sunflower
Helianthus annuuse0 - Treatment
- high pH in the nutrient solutione1
- Outcome
- uptake and shoot translocation of Fee1
- Direction
- restrictede1
- Qualifier
- independently of N forme1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
e1“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 NO3 supply up to 40 mM did not change the relative distribution of Fe between leaf apoplast and symplast at constant low external pH.
- Taxon
- sunflowerHelianthus annuuse0
- Treatment
- Root NO(3)(-) supply (up to 40 mM)e2
- Outcome
- relative distribution of Fe between leaf apoplast and symplaste2
- Direction
- no_changeinferrede2
- Qualifier
- at constant low external pH of the root mediume2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
e2“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 solution into the leaf apoplast restricted 59Fe uptake rate compared with low apoplastic pH.
- Taxon
- sunflowerHelianthus annuuse0
- Treatment
- perfusion of high pH-buffered solution (7.0) into the leaf apoplaste3
- Outcome
- (59)Fe uptake ratee3
- Direction
- restrictede3
- Comparator
- low apoplastic solution pH (5.0 and 6.0, respectively)e3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
e3“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 NO3 (6 mM) into the leaf apoplast had no effect on 59Fe uptake by the leaf symplast.
- Taxon
- sunflowerHelianthus annuuse0
- Treatment
- loading of NO(3)(-) (6 mM)e4
- Outcome
- (59)Fe uptake by the symplast of leaf cellse4
- Direction
- no_changeinferrede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
e4“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, independently of apoplastic pH or apoplastic NO3.
- Taxon
- sunflowerHelianthus annuuse0
- Treatment
- high light intensitye5
- Outcome
- (59)Fe uptakee5
- Direction
- increasede5
- Qualifier
- independently of apoplastic pH or of the presence of NO(3)(-) in the apoplastic solutione5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
e5“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 indication that root NO3 supply inactivates Fe in the leaf apoplast.
- Taxon
- sunflowerHelianthus annuuse0
- Treatment
- NO(3)(-) supply to rootse6
- Outcome
- inactivation of Fe in the leaf apoplaste6
- Direction
- no_changeinferrede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
e6“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 through inhibited Fe acquisition by roots due to high pH at the root surface.
- Taxon
- sunflowerHelianthus annuuse0
- Outcome
- Fe deficiency chlorosise7
- Qualifier
- exclusively by inhibited Fe acquisition by roots due to high pH at the root surfacee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
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”
The same questions in other papers
fertilization · nutrient: content · Helianthus annuus (common sunflower)Positive and negative results
6 papers in the same direction as this paper · 64 in the opposite direction
- positive
- positive
- positive
67 papers more in this group
See all 71 papers →alkalinity · nutrient: content · Helianthus annuus (common sunflower)Results agree
2 papers in the same direction as this paper
- negative
- negative
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.