Abstract
BACKGROUND AND AIMS: Adventitious root (AR) formation in Petunia hybrida is inhibited by low nitrogen fertilization of stock plants but promoted by dark incubation of cuttings before planting. We investigated whether the plant hormone auxin is involved in nitrogen- and dark-mediated AR formation. METHODS: Concentrations of indole-3-acetic acid (IAA) and RNA accumulation of genes controlling auxin homeostasis and function were monitored in the stem base in response to high versus low nitrogen supply to stock plants and to temporal dark vs. light exposure of cuttings by use of GC-MS/MS, a petunia-specific microarray and quantitative RT-PCR. Auxin source capacity, polar auxin transport in cuttings and auxin concentration in the rooting zone were manipulated to investigate the functional contribution of auxin homeostasis and response to the effects of nitrogen fertilization and dark exposure on rooting. KEY RESULTS: The nitrogen content of cuttings had only a marginal effect on IAA concentration in the stem base. Dark incubation enhanced the accumulation of IAA in the stem base during AR induction independent of nitrogen level. Early IAA accumulation in the dark depended on the upper shoot as an auxin source and was enhanced after apical IAA supply. Dark exposure stimulated RNA accumulation of auxin-related genes. In particular, expression of Ph-PIN1 and of genes controlling auxin signalling, including Ph-IAA14, Ph-ARF8, Ph-ARF10 and Ph-SAUR14, was enhanced, while the latter four were repressed in nitrogen-limited cuttings, particularly in the dark. Dark stimulation of rooting depended on polar auxin transport. Basal auxin application partially substituted the effect of dark exposure on rooting, whereas the auxin response of AR formation was strongly depressed by nitrogen limitation. CONCLUSIONS: Increased auxin delivery from the upper shoot and enhanced auxin signalling in the stem base contribute to dark-stimulated AR formation, while nitrogen limitation inhibits AR formation downstream of the auxin signal.
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Claims 12
Claim · model-written summary
Nitrogen content had a marginal effect on stem-base IAA concentration.
- Taxon
- Petunia hybrida
Petunia ×hybridae0 - Organ / stage
- stem basee1
- Treatment
- nitrogen content of cuttingse1
- Outcome
- IAA concentratione1
- Qualifier
- only a marginal effecte1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“The nitrogen content of cuttings had only a marginal effect on IAA concentration in the stem base.”
Claim · model-written summary
Dark incubation enhanced stem-base IAA accumulation during root induction independent of nitrogen.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Organ / stage
- stem basee1
- Treatment
- Dark incubatione1
- Outcome
- accumulation of IAAe1
- Direction
- enhancede1
- Qualifier
- independent of nitrogen levele1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“Dark incubation enhanced the accumulation of IAA in the stem base during AR induction independent of nitrogen level.”
Claim · model-written summary
Early IAA accumulation in darkness depended on the upper shoot as an auxin source.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Organ / stage
- upper shoote1
- Outcome
- IAA accumulatione1
- Qualifier
- as an auxin sourcee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“Early IAA accumulation in the dark depended on the upper shoot as an auxin source”
Claim · model-written summary
Apical IAA supply enhanced early IAA accumulation.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Treatment
- apical IAA supplye1
- Outcome
- Early IAA accumulatione1
- Direction
- enhancede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“Early IAA accumulation in the dark depended on the upper shoot as an auxin source and was enhanced after apical IAA supply.”
Claim · model-written summary
Dark exposure stimulated RNA accumulation of auxin-related genes.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Treatment
- Dark exposuree1
- Outcome
- RNA accumulation of auxin-related genese1
- Direction
- stimulatede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“Dark exposure stimulated RNA accumulation of auxin-related genes.”
Claim · model-written summary
Dark exposure enhanced Ph-PIN1 expression and expression of auxin-signalling genes.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Gene
- Ph-PIN1e1
- Outcome
- expression of Ph-PIN1 and of genes controlling auxin signallinge1
- Direction
- enhancede1
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“expression of Ph-PIN1 and of genes controlling auxin signalling, including Ph-IAA14, Ph-ARF8, Ph-ARF10 and Ph-SAUR14, was enhanced”
Claim · model-written summary
Nitrogen limitation repressed four auxin-signalling genes, particularly in darkness.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Treatment
- nitrogen-limited cuttingse1
- Gene
- Ph-IAA14, Ph-ARF8, Ph-ARF10 and Ph-SAUR14e1
- Outcome
- the latter foure1
- Direction
- repressede1
- Qualifier
- particularly in the darke1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“Ph-IAA14, Ph-ARF8, Ph-ARF10 and Ph-SAUR14, was enhanced, while the latter four were repressed in nitrogen-limited cuttings, particularly in the dark.”
Claim · model-written summary
Dark stimulation of rooting depended on polar auxin transport.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Outcome
- rootinge1
- Qualifier
- polar auxin transporte1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“Dark stimulation of rooting depended on polar auxin transport.”
Claim · model-written summary
Basal auxin application partially substituted for darkness in rooting.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Treatment
- Basal auxin applicatione1
- Outcome
- rootinge1
- Comparator
- dark exposuree1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“Basal auxin application partially substituted the effect of dark exposure on rooting”
Claim · model-written summary
Nitrogen limitation strongly depressed the auxin response of root formation.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Treatment
- nitrogen limitatione1
- Outcome
- auxin response of AR formatione1
- Direction
- strongly depressede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“the auxin response of AR formation was strongly depressed by nitrogen limitation”
Claim · model-written summary
Authors infer that upper-shoot auxin delivery and stem-base signalling contribute to dark-stimulated rooting.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Organ / stage
- stem basee1
- Outcome
- dark-stimulated AR formatione1
- Qualifier
- Increased auxin delivery from the upper shoot and enhanced auxin signallinge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“Increased auxin delivery from the upper shoot and enhanced auxin signalling in the stem base contribute to dark-stimulated AR formation”
Claim · model-written summary
Authors infer that nitrogen limitation inhibits root formation downstream of auxin signalling.
- Taxon
- Petunia hybridaPetunia ×hybridae0
- Treatment
- nitrogen limitatione1
- Outcome
- AR formatione1
- Qualifier
- downstream of the auxin signale1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Petunia hybrida”
e1“nitrogen limitation inhibits AR formation downstream of the auxin signal.”
The same questions in other papers
class · growth · Petunia x hybrida (garden petunia)Positive and negative results
3 papers in the same direction as this paper · 3 in the opposite direction
- negative
- negative
- negative
3 papers more in this group
See all 7 papers →light · molecular: expression · Petunia x hybrida (garden petunia)Results agree
1 paper in the same direction as this paper
- positive
nitrogen · growth · Petunia x hybrida (garden petunia)Results agree
2 papers in the same direction as this paper
This paper is about lacking the nutrient, so it counts the other way round here.
- positive
- 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.