Two photobiological pathways of phytochrome A activity, only one of which shows dominant negative suppression by phytochrome B
The plant receptor phytochrome A (phyA) mediates responses like hypocotyl growth inhibition and cotyledon unfolding that require continuous far-red (FR) light for maximum expression (high-irradiance responses, HIR), and responses like seed germination that can be induced by a single pulse of FR (ver...
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todo:paper_00318655_v71_n4_p481_Casal2023-10-03T14:41:34Z Two photobiological pathways of phytochrome A activity, only one of which shows dominant negative suppression by phytochrome B Casal, J.J. Yanovsky, M.J. Luppi, J.P. phytochrome phytochrome A phytochrome B receptor unclassified drug Arabidopsis article controlled study cotyledon darkness exposure germination growth inhibition nonhuman plant growth seedling Arabidopsis Arabidopsis Proteins Darkness Infrared Rays Photoreceptors Phytochrome Phytochrome A Phytochrome B Transcription Factors Arabidopsis Arabidopsis thaliana The plant receptor phytochrome A (phyA) mediates responses like hypocotyl growth inhibition and cotyledon unfolding that require continuous far-red (FR) light for maximum expression (high-irradiance responses, HIR), and responses like seed germination that can be induced by a single pulse of FR (very-low-fluence responses, VLFR). It is not known whether this duality results from either phyA interaction with different end-point processes or from the intrinsic properties of phyA activity. Etiolated seedlings of Arabidopsis thaliana were exposed to pulses of FR (3 min) separated by dark intervals of different duration. Hypocotyl-growth inhibition and cotyledon unfolding showed two phases. The first phase (VLFR) between 0.17 and 0.5 pulses·h-1, a plateau between 0.5 and 2 pulses·h-1 and a second phase (HIR) at higher frequencies. Reciprocity between fluence rate and duration of FR was observed within phases, not between phases. The fluence rate for half the maximum effect was 0.1 and 3 μmol·m-2-s-1 for hourly pulses of FR (VLFR) and continuous FR (HIR), respectively. Overexpression of phytochrome B caused dominant negative suppression under continuous but not under hourly FR. We conclude that phyA is intrinsically able to initiate two discrete photoresponses even when a single end-point process is considered. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00318655_v71_n4_p481_Casal |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
phytochrome phytochrome A phytochrome B receptor unclassified drug Arabidopsis article controlled study cotyledon darkness exposure germination growth inhibition nonhuman plant growth seedling Arabidopsis Arabidopsis Proteins Darkness Infrared Rays Photoreceptors Phytochrome Phytochrome A Phytochrome B Transcription Factors Arabidopsis Arabidopsis thaliana |
| spellingShingle |
phytochrome phytochrome A phytochrome B receptor unclassified drug Arabidopsis article controlled study cotyledon darkness exposure germination growth inhibition nonhuman plant growth seedling Arabidopsis Arabidopsis Proteins Darkness Infrared Rays Photoreceptors Phytochrome Phytochrome A Phytochrome B Transcription Factors Arabidopsis Arabidopsis thaliana Casal, J.J. Yanovsky, M.J. Luppi, J.P. Two photobiological pathways of phytochrome A activity, only one of which shows dominant negative suppression by phytochrome B |
| topic_facet |
phytochrome phytochrome A phytochrome B receptor unclassified drug Arabidopsis article controlled study cotyledon darkness exposure germination growth inhibition nonhuman plant growth seedling Arabidopsis Arabidopsis Proteins Darkness Infrared Rays Photoreceptors Phytochrome Phytochrome A Phytochrome B Transcription Factors Arabidopsis Arabidopsis thaliana |
| description |
The plant receptor phytochrome A (phyA) mediates responses like hypocotyl growth inhibition and cotyledon unfolding that require continuous far-red (FR) light for maximum expression (high-irradiance responses, HIR), and responses like seed germination that can be induced by a single pulse of FR (very-low-fluence responses, VLFR). It is not known whether this duality results from either phyA interaction with different end-point processes or from the intrinsic properties of phyA activity. Etiolated seedlings of Arabidopsis thaliana were exposed to pulses of FR (3 min) separated by dark intervals of different duration. Hypocotyl-growth inhibition and cotyledon unfolding showed two phases. The first phase (VLFR) between 0.17 and 0.5 pulses·h-1, a plateau between 0.5 and 2 pulses·h-1 and a second phase (HIR) at higher frequencies. Reciprocity between fluence rate and duration of FR was observed within phases, not between phases. The fluence rate for half the maximum effect was 0.1 and 3 μmol·m-2-s-1 for hourly pulses of FR (VLFR) and continuous FR (HIR), respectively. Overexpression of phytochrome B caused dominant negative suppression under continuous but not under hourly FR. We conclude that phyA is intrinsically able to initiate two discrete photoresponses even when a single end-point process is considered. |
| format |
JOUR |
| author |
Casal, J.J. Yanovsky, M.J. Luppi, J.P. |
| author_facet |
Casal, J.J. Yanovsky, M.J. Luppi, J.P. |
| author_sort |
Casal, J.J. |
| title |
Two photobiological pathways of phytochrome A activity, only one of which shows dominant negative suppression by phytochrome B |
| title_short |
Two photobiological pathways of phytochrome A activity, only one of which shows dominant negative suppression by phytochrome B |
| title_full |
Two photobiological pathways of phytochrome A activity, only one of which shows dominant negative suppression by phytochrome B |
| title_fullStr |
Two photobiological pathways of phytochrome A activity, only one of which shows dominant negative suppression by phytochrome B |
| title_full_unstemmed |
Two photobiological pathways of phytochrome A activity, only one of which shows dominant negative suppression by phytochrome B |
| title_sort |
two photobiological pathways of phytochrome a activity, only one of which shows dominant negative suppression by phytochrome b |
| url |
http://hdl.handle.net/20.500.12110/paper_00318655_v71_n4_p481_Casal |
| work_keys_str_mv |
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| _version_ |
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