Abstract
The developmental transition of the meristem from vegetative to reproductive growth is controlled by the cyclic alternation of light and darkness in photoperiodic plants. Photoperiod is perceived in the leaves or cotyledons, where a flower-inducing signal is produced and transmitted to the apex. To begin to understand the molecular basis of the photoperiodic induction of flowering, we investigated changes in gene expression at the level of mRNA abundance that occur in association with dark induction of flowering in the short-day species Pharbitis nil. Several cDNAs were isolated that corresponded to mRNAs whose abundance is altered after the transition to darkness. The pattern of increase in mRNA levels corresponding to one cDNA clone, PN1, showed a dark-induced maximum at 8 h of darkness, whereas a second clone, PN9, showed a dark-induced accumulation of mRNA with peak levels at 12 to 16 h of darkness. When plants were held in continuous darkness, both PN1 and PN9 exhibited rhythmic patterns of mRNA accumulation with an approximate circadian periodicity, suggesting that their expression is under the control of an endogenous clock. The observed pattern of expression of PN1 and PN9 in cotyledon tissue was unusual in that darkness rather than light promoted mRNA accumulation, which is a temporal pattern of expression distinct from that of several other Pharbitis genes, including Cab, PsaG, and actin, whose mRNAs were most prevalent or equally prevalent in the light. Brief illumination of an inductive dark period by a red light night break strongly inhibited the accumulation of both PN1 and PN9 mRNA. The expression of both PN1 and PN9 was spatially regulated in that mRNA transcripts were detected in the cotyledons and stems, but not the roots, of photoperiodically competent seedlings. Both PN1 and PN9 appeared to be present as single-copy genes in the Pharbitis genome. Sequence analysis has not determined the identity of these genes. Overall, the accumulation of mRNAs corresponding to both PN1 and PN9 closely paralleled the process of photoperiodic floral induction in P. nil, but a clear involvement with this process cannot be established from our findings because of the difficulty of separating photoperiodic events from other light-regulated processes, especially those involved in photosynthesis, such as Cab gene expression. These results identify the products of circadian-regulated genes in photoreceptive tissue of P. nil and support the concept that circadian-regulated gene expression interacting with darkness may be involved in the regulation of photoperiodically controlled physiological processes, including flower induction.
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Claims 11
Claim · model-written summary
Several cDNAs corresponded to transcripts altered after the transition to darkness.
- Taxon
- Pharbitis nil
Ipomoea nilt0 - Treatment
- transition to darknesse0
- Outcome
- mRNAs whose abundance is alterede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Several cDNAs were isolated that corresponded to mRNAs whose abundance is altered after the transition to darkness.”
t0“Pharbitis nil”
Claim · model-written summary
PN1 mRNA rose to a dark-induced maximum after 8 h.
- Taxon
- Pharbitis nilIpomoea nilt0
- Treatment
- darknesse0
- Gene
- PN1e0
- Outcome
- mRNA levelse0
- Direction
- increasee0
- Value
- 8 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The pattern of increase in mRNA levels corresponding to one cDNA clone, PN1, showed a dark-induced maximum at 8 h of darkness”
t0“Pharbitis nil”
Claim · model-written summary
PN9 mRNA accumulated in darkness and peaked at 12 to 16 h.
- Taxon
- Pharbitis nilIpomoea nilt0
- Treatment
- darknesse0
- Gene
- PN9e0
- Outcome
- accumulation of mRNAe0
- Direction
- peake0
- Value
- 12 to 16 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a second clone, PN9, showed a dark-induced accumulation of mRNA with peak levels at 12 to 16 h of darkness”
t0“Pharbitis nil”
Claim · model-written summary
PN1 and PN9 transcripts accumulated rhythmically with approximate circadian periodicity in continuous darkness.
- Taxon
- Pharbitis nilIpomoea nilt0
- Treatment
- continuous darknesse0
- Gene
- PN1 and PN9e0
- Outcome
- rhythmic patterns of mRNA accumulatione0
- Qualifier
- approximate circadian periodicitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When plants were held in continuous darkness, both PN1 and PN9 exhibited rhythmic patterns of mRNA accumulation with an approximate circadian periodicity”
t0“Pharbitis nil”
Claim · model-written summary
Darkness promoted PN1 and PN9 transcript accumulation in cotyledons, unlike the light prevalence of Cab, PsaG and actin transcripts.
- Taxon
- Pharbitis nilIpomoea nilt0
- Gene
- Cab, PsaG, and actine0
- Outcome
- mRNA accumulatione0
- Direction
- promotede0
- Comparator
- lighte0
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“darkness rather than light promoted mRNA accumulation, which is a temporal pattern of expression distinct from that of several other Pharbitis genes, including Cab, PsaG, and actin, whose mRNAs were most prevalent or equally prevalent in the light”
t0“Pharbitis nil”
Claim · model-written summary
A red-light night break strongly inhibited PN1 and PN9 mRNA accumulation.
- Taxon
- Pharbitis nilIpomoea nilt0
- Treatment
- red light night breake0
- Gene
- PN1 and PN9e0
- Outcome
- accumulation of both PN1 and PN9 mRNAe0
- Direction
- inhibitede0
- Comparator
- inductive dark periode0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Brief illumination of an inductive dark period by a red light night break strongly inhibited the accumulation of both PN1 and PN9 mRNA.”
t0“Pharbitis nil”
Claim · model-written summary
PN1 and PN9 transcripts occurred in cotyledons and stems but not roots of competent seedlings.
- Taxon
- Pharbitis nilIpomoea nilt0
- Organ / stage
- photoperiodically competent seedlingse0
- Gene
- PN1 and PN9e1
- Outcome
- mRNA transcripts were detected in the cotyledons and stems, but not the rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mRNA transcripts were detected in the cotyledons and stems, but not the roots, of photoperiodically competent seedlings”
e1“The expression of both PN1 and PN9 was spatially regulated”
t0“Pharbitis nil”
Claim · model-written summary
PN1 and PN9 appeared to be single-copy genes.
- Taxon
- Pharbitis nilIpomoea nilt0
- Gene
- PN1 and PN9e0
- Outcome
- single-copy genese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both PN1 and PN9 appeared to be present as single-copy genes in the Pharbitis genome.”
t0“Pharbitis nil”
Claim · model-written summary
Sequence analysis did not identify PN1 and PN9.
- Taxon
- Pharbitis nilIpomoea nilt0
- Outcome
- identity of these genese0
Not reportedGene
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sequence analysis has not determined the identity of these genes.”
t0“Pharbitis nil”
Claim · model-written summary
PN1 and PN9 mRNA accumulation closely paralleled photoperiodic floral induction, without establishing their involvement.
- Taxon
- Pharbitis nilIpomoea nilt0
- Gene
- PN1 and PN9e0
- Outcome
- photoperiodic floral inductione0
- Qualifier
- a clear involvement with this process cannot be establishede0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the accumulation of mRNAs corresponding to both PN1 and PN9 closely paralleled the process of photoperiodic floral induction in P. nil, but a clear involvement with this process cannot be established from our findings”
t0“Pharbitis nil”
Claim · model-written summary
The authors suggest circadian-regulated expression interacting with darkness may regulate photoperiodic processes including flower induction.
- Taxon
- Pharbitis nilIpomoea nilt0
- Outcome
- flower inductione0
- Qualifier
- circadian-regulated gene expression interacting with darknesse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“circadian-regulated gene expression interacting with darkness may be involved in the regulation of photoperiodically controlled physiological processes, including flower induction”
t0“Pharbitis nil”
The same questions in other papers
light · molecular: expression · Ipomoea nil (Japanese morning glory)Positive and negative results
4 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- negative
2 papers more in this group
See all 6 papers →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.