Abstract
We sought to determine if phytochrome B (phyB)-mediated responses to the red light (R)/far-red light (FR) ratio are affected by phytochrome A (phyA) activity in light-grown seedlings of Arabidopsis thaliana. Pulses of FR delayed into the dark period were less effective than end-of-day (EOD) FR in promoting hypocotyl growth over a given period in darkness. White light minus blue light interposed instead of darkness between the end of the white-light photoperiod and the FR pulse was sufficient to maintain responsivity to the decrease in phyB in FR-light-absorbing form in wild-type (WT) seedlings, but not in the phyA mutant. Compared with EOD R, hourly R+FR pulses provided throughout the night caused a stronger promotion of stem growth than a single EOD R+FR pulse in WT Arabidopsis, cucumber, mustard, sunflower, tobacco, and tomato, but not in phyA Arabidopsis or in the aurea mutant of tomato. WT seedlings of Arabidopsis responded to a range of high EOD R/FR ratios, whereas the phyA mutant required stronger reductions in the EOD R/FR ratio. In sunlight, phyA seedlings of Arabidopsis showed no response to the "early warning" signals of neighboring vegetation, and hypocotyl-growth promotion occurred at higher plant densities than in the WT. Thus, under a series of light conditions, the sensitivity or responsivity to reductions in the R/FR ratio were larger in WT than in phyA seedlings. A product of phyA is therefore proposed to enhance the hypocotyl-growth response to decreases in phyB in FR-light-absorbing form in light grown seedlings.
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Claims 9
Claim · model-written summary
Delayed far-red pulses promoted less hypocotyl growth than end-of-day pulses.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianat0 - Treatment
- Pulses of FR delayed into the dark periode0
- Outcome
- hypocotyl growthe0
- Direction
- less effectivee0
- Comparator
- end-of-day (EOD) FRe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pulses of FR delayed into the dark period were less effective than end-of-day (EOD) FR in promoting hypocotyl growth”
t0“Arabidopsis thaliana”
Claim · model-written summary
Interposed white light minus blue maintained wild-type seedling responsivity.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- wild-type (WT) seedlingse0
- Treatment
- White light minus blue lighte0
- Gene
- phyBe0
- Outcome
- responsivitye0
- Direction
- maintaine0
- Comparator
- darknesse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“White light minus blue light interposed instead of darkness between the end of the white-light photoperiod and the FR pulse was sufficient to maintain responsivity to the decrease in phyB in FR-light-absorbing form in wild-type (WT) seedlings”
t0“Arabidopsis thaliana”
Claim · model-written summary
The interposed light failed to maintain responsivity in the phyA mutant.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- phyA mutante0
- Outcome
- not in the phyA mutante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but not in the phyA mutant”
t0“Arabidopsis thaliana”
Claim · model-written summary
Hourly R+FR pulses promoted more stem growth than one end-of-day pulse in wild-type Arabidopsis and five other named plants.
- Taxon
- ArabidopsisArabidopsise0
- Treatment
- hourly R+FR pulsese0
- Outcome
- stem growthe0
- Direction
- stronger promotione0
- Qualifier
- cucumber, mustard, sunflower, tobacco, and tomatoe0
- Comparator
- single EOD R+FR pulsee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“hourly R+FR pulses provided throughout the night caused a stronger promotion of stem growth than a single EOD R+FR pulse in WT Arabidopsis, cucumber, mustard, sunflower, tobacco, and tomato”
Claim · model-written summary
Wild-type Arabidopsis responded to high end-of-day R/FR ratios.
- Taxon
- ArabidopsisArabidopsise0
- Material
- WT seedlingse0
- Outcome
- responded to a range of high EOD R/FR ratiose0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“WT seedlings of Arabidopsis responded to a range of high EOD R/FR ratios”
Claim · model-written summary
The phyA mutant required stronger reductions in end-of-day R/FR ratio.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- phyA mutante0
- Outcome
- required stronger reductions in the EOD R/FR ratioe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the phyA mutant required stronger reductions in the EOD R/FR ratio”
t0“Arabidopsis thaliana”
Claim · model-written summary
In sunlight phyA seedlings did not respond to early warning signals from neighbors.
- Taxon
- ArabidopsisArabidopsise0
- Material
- phyA seedlingse0
- Outcome
- no response to the "early warning" signals of neighboring vegetatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In sunlight, phyA seedlings of Arabidopsis showed no response to the "early warning" signals of neighboring vegetation”
Claim · model-written summary
Hypocotyl growth promotion in phyA seedlings required higher density than wild type.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- phyA seedlingse1
- Outcome
- hypocotyl-growth promotione0
- Direction
- highere0
- Comparator
- WTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“hypocotyl-growth promotion occurred at higher plant densities than in the WT”
e1“In sunlight, phyA seedlings of Arabidopsis showed no response to the "early warning" signals of neighboring vegetation”
t0“Arabidopsis thaliana”
Claim · model-written summary
Phytochrome A is proposed to enhance the growth response to reduced phytochrome B activity.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- phyAe0
- Outcome
- hypocotyl-growth responsee0
- Qualifier
- decreases in phyB in FR-light-absorbing forme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A product of phyA is therefore proposed to enhance the hypocotyl-growth response to decreases in phyB in FR-light-absorbing form”
t0“Arabidopsis thaliana”
The same questions in other papers
light · growth · Arabidopsis thaliana (thale cress)Results differ
13 papers in the same direction as this paper · 30 in the opposite direction
- positive
- positive
- positive
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