Abstract
In intact plants, the shoot apex grows predominantly and inhibits outgrowth of axillary buds. After decapitation of the shoot apex, outgrowth of axillary buds begins. This phenomenon is called an apical dominance. Although the involvement of auxin, which represses outgrowth of axillary buds, and cytokinin (CK), which promotes outgrowth of axillary buds, has been proposed, little is known about the underlying molecular mechanisms. In the present study, we demonstrated that auxin negatively regulates local CK biosynthesis in the nodal stem by controlling the expression level of the pea (Pisum sativum L.) gene adenosine phosphate-isopentenyltransferase (PsIPT), which encodes a key enzyme in CK biosynthesis. Before decapitation, PsIPT1 and PsIPT2 transcripts were undetectable; after decapitation, they were markedly induced in the nodal stem along with accumulation of CK. Expression of PsIPT was repressed by the application of indole-3-acetic acid (IAA). In excised nodal stem, PsIPT expression and CK levels also increased under IAA-free conditions. Furthermore, beta-glucuronidase expression, under the control of the PsIPT2 promoter region in transgenic Arabidopsis, was repressed by an IAA. Our results indicate that in apical dominance one role of auxin is to repress local biosynthesis of CK in the nodal stem and that, after decapitation, CKs, which are thought to be derived from the roots, are locally biosynthesized in the nodal stem rather than in the roots.
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Claims 9
Claim · model-written summary
Auxin negatively regulates local cytokinin biosynthesis through PsIPT expression in pea nodal stem.
- Taxon
- pea (Pisum sativum L.)
Lathyrus oleraceuse0 - Organ / stage
- nodal steme0
- Gene
- adenosine phosphate-isopentenyltransferase (PsIPT)e0
- Compound
- auxine0
- Outcome
- local CK biosynthesise0
- Direction
- negatively regulatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“auxin negatively regulates local CK biosynthesis in the nodal stem by controlling the expression level of the pea (Pisum sativum L.) gene adenosine phosphate-isopentenyltransferase (PsIPT)”
Claim · model-written summary
PsIPT1 and PsIPT2 transcripts were undetectable before decapitation.
- Taxon
- pea (Pisum sativum L.)Lathyrus oleraceuse1
- Gene
- PsIPT1 and PsIPT2e0
- Outcome
- PsIPT1 and PsIPT2 transcripts were undetectablee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Before decapitation, PsIPT1 and PsIPT2 transcripts were undetectable”
e1“pea (Pisum sativum L.)”
Claim · model-written summary
Decapitation markedly induced PsIPT1 and PsIPT2 transcripts in the nodal stem.
- Taxon
- pea (Pisum sativum L.)Lathyrus oleraceuse1
- Treatment
- decapitatione0
- Outcome
- PsIPT1 and PsIPT2 transcriptse2
- Direction
- markedly inducede0
- Comparator
- Before decapitatione2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“after decapitation, they were markedly induced in the nodal stem”
e1“pea (Pisum sativum L.)”
e2“Before decapitation, PsIPT1 and PsIPT2 transcripts were undetectable”
Claim · model-written summary
Decapitation accumulated cytokinin in the pea nodal stem.
- Taxon
- pea (Pisum sativum L.)Lathyrus oleraceuse1
- Treatment
- decapitatione0
- Outcome
- accumulation of CKe0
- Direction
- accumulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“after decapitation, they were markedly induced in the nodal stem along with accumulation of CK”
e1“pea (Pisum sativum L.)”
Claim · model-written summary
IAA application repressed PsIPT expression.
- Taxon
- pea (Pisum sativum L.)Lathyrus oleraceuse1
- Treatment
- application of indole-3-acetic acid (IAA)e0
- Gene
- PsIPTe0
- Outcome
- Expression of PsIPTe0
- Direction
- repressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Expression of PsIPT was repressed by the application of indole-3-acetic acid (IAA)”
e1“pea (Pisum sativum L.)”
Claim · model-written summary
IAA-free conditions increased PsIPT expression in excised nodal stems.
- Taxon
- pea (Pisum sativum L.)Lathyrus oleraceuse1
- Organ / stage
- excised nodal steme0
- Treatment
- IAA-free conditionse0
- Outcome
- PsIPT expressione0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In excised nodal stem, PsIPT expression and CK levels also increased under IAA-free conditions”
e1“pea (Pisum sativum L.)”
Claim · model-written summary
IAA-free conditions increased cytokinin levels in excised nodal stems.
- Taxon
- pea (Pisum sativum L.)Lathyrus oleraceuse1
- Organ / stage
- excised nodal steme0
- Treatment
- IAA-free conditionse0
- Outcome
- CK levelse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In excised nodal stem, PsIPT expression and CK levels also increased under IAA-free conditions”
e1“pea (Pisum sativum L.)”
Claim · model-written summary
IAA repressed PsIPT2 promoter-driven reporter expression in transgenic Arabidopsis.
- Taxon
- Arabidopsis
Arabidopsise0 - Treatment
- IAAe0
- Gene
- PsIPT2 promoter regione0
- Outcome
- beta-glucuronidase expressione0
- Direction
- repressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“beta-glucuronidase expression, under the control of the PsIPT2 promoter region in transgenic Arabidopsis, was repressed by an IAA”
Claim · model-written summary
The authors infer that pea nodal stems synthesize CK locally after decapitation.
- Taxon
- pea (Pisum sativum L.)Lathyrus oleraceuse1
- Organ / stage
- nodal steme0
- Outcome
- CKs, which are thought to be derived from the roots, are locally biosynthesized in the nodal stem rather than in the rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“after decapitation, CKs, which are thought to be derived from the roots, are locally biosynthesized in the nodal stem rather than in the roots”
e1“pea (Pisum sativum L.)”
The same questions in other papers
indole-3-acetic acid · molecular: expression · Lathyrus oleraceus (pea)Positive and negative results
3 papers in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- negative
2 papers more in this group
See all 6 papers →pruning · physiology: hormones · Lathyrus oleraceus (pea)Positive and negative results
1 in the opposite direction
- negative
pruning · molecular: expression · Lathyrus oleraceus (pea)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- negative
- positive
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.