484:) Exposure to UV- light in plants mediates biochemical pathways, photosynthesis, plant growth and many other processes essential to plant development. The UV-B photoreceptor, UV Resistance Locus8 (UVR8) detects UV-B rays and elicits photomorphogenic responses. These response are important for initiating hypocotyl elongation, leaf expansion, biosynthesis of flavonoids and many other important processes that affect the root-shoot system. Exposure to UV-B rays can be damaging to DNA inside of the plant cells, however, UVR8 induces genes required to acclimate plants to UV-B radiation, these genes are responsible for many biosynthesis pathways that involve protection from UV damage, oxidative stress, and photorepair of DNA damage.
191:
437:, an enzyme that carries out light-dependent repair of UV damaged DNA. There are two different forms of cryptochromes that have been identified in plants, CRY1 and CRY2, which regulate the inhibition of hypocotyl elongation in response to blue light. Cryptochromes control stem elongation, leaf expansion, circadian rhythms and flowering time. In addition to blue light, cryptochromes also perceive long wavelength
357:, an apoprotein combined with its prosthetic group, becomes sensitive to light. If it absorbs red light it will change conformation to the biologically active Pfr form. The Pfr form can absorb far red light and switch back to the Pr form. The Pfr promotes and regulates photomorphogenesis in response to FR light, whereas Pr regulates de-etiolation in response to R light.
374:. PHYA is involved in the regulation of photomorphogenesis in response to far-red light. PHYB is involved in regulating photoreversible seed germination in response to red light. PHYC mediates the response between PHYA and PHYB. PHYD and PHYE mediate elongation of the internode and control the time in which the plant flowers.
328:
to detect and respond to red and far-red wavelengths. Phytochromes are signaling proteins that promote photomorphogenesis in response to red light and far-red light. Phytochrome is the only known photoreceptor that absorbs light in the red/far red spectrum of light (600-750 nm) specifically and
150:
appears as the root becomes established. Later, with growth of the shoot (particularly when it emerges into the light) there is increased secondary root formation and branching. In this coordinated progression of developmental responses are early manifestations of correlative growth phenomena where
287:
and involves using red photoreceptors (phytochromes) to determine the daylength. As a result, photoperiodic plants only start making flowers when the days have reached a "critical daylength," allowing these plants to initiate their flowering period according to the time of year. For example, "long
340:
There are two forms of phytochromes: red light absorbing, Pr, and far-red light absorbing, Pfr. Pfr, which is the active form of phytochromes, can be reverted to Pr, which is the inactive form, slowly by inducing darkness or more rapidly by irradiation by far-red light. The phytochrome
487:
There is still much to be discovered about the mechanisms involved in UV-B radiation and UVR8. Scientists are working to understand the pathways responsible for plant UV receptors response to solar radiation in natural environments.
364:. The different forms of phytochrome control different responses but there is also redundancy so that in the absence of one phytochrome, another may take on the missing functions. There are five genes that encode phytochromes in the
291:
Photoperiodism also has an effect on vegetative growth, including on bud dormancy in perennial plants, though this is not as well-documented as the effect of photoperiodism on the switch to the flowering stage.
67:
to grow the plants. There are at least three stages of plant development where photomorphogenesis occurs: seed germination, seedling development, and the switch from the vegetative to the flowering stage
399:
it was the opposite, where far-red light exposure caused the root tips to adhere, and red light caused the roots to detach. This effect of red and far-red light on root tips is now known as the
429:
were the first blue light receptors to be isolated and characterized from any organism, and are responsible for the blue light reactions in photomorphogenesis. The proteins use a
300:
Typically, plants are responsive to wavelengths of light in the blue, red and far-red regions of the spectrum through the action of several different photosensory systems. The
283:
Some plants rely on light signals to determine when to switch from the vegetative to the flowering stage of plant development. This type of photomorphogenesis is known as
1108:
Aphalo, Pedro J.; Tegelberg, Riitta; Lindfors, Anders V.; Strid, Åke; Sipari, Nina; Wargent, Jason J.; Jenkins, Gareth I.; Vainonen, Julia; Brosché, Mikael (2013-02-01).
122:
introduced the term "etiolement" to the scientific literature in 1754 when describing his experiments, commenting that the term was already in use by gardeners.
395:
adhered to the sides of a beaker with a negatively charged surface after being treated with red light, yet released after being exposed to far-red light. For
178:(dark development), which is characterized by etiolation. Upon exposure to light, the seedling switches rapidly to photomorphogenesis (light development).
175:
316:. The combination of phytochromes and cryptochromes mediate growth and the flowering of plants in response to red light, far-red light, and blue light.
1110:"Multiple Roles for UV Resistance Locus8 in Regulating Gene Expression and Metabolite Accumulation in Arabidopsis under Solar Ultraviolet Radiation"
243:
205:
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and molecular analyses, it has been determined that higher plants contain at least 4, and probably 5, different blue light photoreceptors.
288:
day" plants need long days to start flowering, and "short day" plants need to experience short days before they will start making flowers.
194:
A dicot seedling emerging from the ground displays an apical hook (in the hypocotyl in this case), a response to dark conditions
635:
581:
28:-mediated development, where plant growth patterns respond to the light spectrum. This is a completely separate process from
102:(371 to 287 BC) may have been the first to write about photomorphogenesis. He described the different wood qualities of
275:
The developmental changes characteristic of photomorphogenesis shown by de-etiolated seedlings, are induced by light.
135:
Light has profound effects on the development of plants. The most striking effects of light are observed when a
329:
only for photosensory purposes. Phytochromes are proteins with a light absorbing pigment attached called a
308:. There are at least 5 members of the phytochrome family of photoreceptors. There are several blue light
1185:
468:
has been shown to be a UV-B receptor. Plants undergo distinct photomorphogenic changes as a result of
151:
the root affects the growth of the shoot and vice versa. To a large degree, the growth responses are
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irradiation (UV-A). Since the cryptochromes were discovered in plants, several labs have identified
345:, a protein that together with a prosthetic group forms a particular biochemical molecule such as a
181:
There are differences when comparing dark-grown (etiolated) and light-grown (de-etiolated) seedlings
1170:
Photobiological
Sciences Online. Resources available from the American Society for Photobiology
171:
of the seedling causes it to become elongated, which may facilitate it emerging from the soil.
75:
Most research on photomorphogenesis is derived from plants studies involving several kingdoms:
784:"A Rapid Photoreversible Response of Barely Root Tips in the Presence of 3-Indoleacetic Acid"
472:
radiation. They have photoreceptors that initiate morphogenetic changes in the plant embryo (
381:(ferns, mosses, algae) and photosynthetic bacteria have shown that phytochromes evolved from
40:
are photochromic sensory receptors that restrict the photomorphogenic effect of light to the
17:
625:
571:
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There are blue light photoreceptors that are not a part of photomorphogenesis. For example,
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genes and photoreceptors in a number of other organisms, including humans, mice and flies.
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Photomorphogenesis in Plants and
Bacteria: Function and Signal Transduction Mechanisms
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Proceedings of the
National Academy of Sciences of the United States of America
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grown in different levels of light, likely the result of the photomorphogenic "
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A seedling that emerges in darkness follows a developmental program known as
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seedling emerges from the soil and is exposed to light for the first time.
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as a chromophore. The cryptochromes have evolved from microbial DNA-
576:. Springer Science & Business Media. pp. 4, 178, 183–184.
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353:, is synthesized in the Pr form. Upon binding the chromophore, the
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653:"From Darkness into Light: Factors Controlling Photomorphogenesis"
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Molecular analyses of phytochrome and phytochrome-like genes in
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956:"Q&A: How do plants sense and respond to UV-B radiation?"
843:"Phytochrome Control of Another Phytochrome-Mediated Process"
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Most plants have multiple phytochromes encoded by different
465:
771:(Sixth ed.). Sunderland, MA: Sinauer Associates, Inc.
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wrote "Historia
Plantarum" which mentioned the effects of
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103:
32:
where light is used as a source of energy. Phytochromes,
767:
Taiz, Lincoln; Zeiger, Eduardo; Møller, Ian Max (2015).
630:. Springer Science & Business Media. pp. 1–2.
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which have different functions. Based on studies with
1057:"Photomorphogenic responses to ultraviolet-B light"
1007:"Photomorphogenic responses to ultraviolet-B light"
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385:photoreceptors that predated the origin of plants.
333:. The chromophore is a linear tetrapyrrole called
1177:
766:
614:
125:
452:is the blue light photoreceptor that controls
304:for red and far-red wavelengths are known as
954:Ulm, Roman; Jenkins, Gareth I (2015-06-30).
146:(root) emerges first from the seed, and the
464:Plants show various responses to UV light.
163:In the absence of light, plants develop an
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52:portions of the electromagnetic spectrum.
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624:Eberhard Schc$ fer; Ferenc Nagy (2006).
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907:"The Cryptochrome Blue Light Receptors"
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510:"The Red Side of Photomorphogenesis"
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271:Lateral root development accelerated
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411:Plants contain multiple blue light
233:Limited production of lateral roots
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713:"Phytochrome Signaling Mechanisms"
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59:is often studied by using tightly
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1055:Jenkins, Gareth I. (2017-11-01).
1005:Jenkins, Gareth I. (2017-11-01).
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905:Yu, Xuhong; et al. (2010).
769:Plant Physiology and Development
711:Li, Jigang; et al. (2011).
651:Eckardt, Nancy A. (2001-02-01).
227:Limited radial expansion of stem
118:(grow in the absence of light).
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391:observed that the root tips of
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573:Lectures on Photomorphogenesis
508:Parks, Brian M. (2003-12-01).
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1064:Plant, Cell & Environment
1014:Plant, Cell & Environment
782:Tanada, Takuma (1968-02-01).
570:Hans Mohr (6 December 2012).
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238:De-etiolated characteristics:
126:Developmental stages affected
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262:Stem elongation suppressed
199:Etiolated characteristics:
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55:The photomorphogenesis of
973:10.1186/s12915-015-0156-y
841:Tanada, T. (1972-01-01).
268:Root elongation promoted
265:Radial expansion of stem
230:Limited root elongation
195:
142:Normally the seedling
100:Theophrastus of Eresus
1126:10.1104/pp.112.211375
801:10.1073/pnas.59.2.376
526:10.1104/pp.103.029702
224:Rapid stem elongation
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18:developmental biology
911:The Arabidopsis Book
717:The Arabidopsis Book
669:10.1105/tpc.13.2.219
598:"Photomorphogenesis"
367:Arabidopsis thaliana
253:Leaf growth promoted
159:Seedling development
859:10.1104/pp.49.4.560
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176:skotomorphogenesis
22:photomorphogenesis
1186:Plant development
1076:10.1111/pce.12934
1070:(11): 2544–2557.
1026:10.1111/pce.12934
1020:(11): 2544–2557.
637:978-1-4020-3809-9
602:photobiology.info
583:978-3-642-65418-3
320:Red/far-red light
110:effect. In 1686,
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167:growth pattern.
131:Seed germination
108:shade-avoidance"
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450:phototropin
383:prokaryotic
355:holoprotein
331:chromophore
326:phytochrome
324:Plants use
257:Chlorophyll
250:splits open
244:Apical hook
220:chlorophyll
208:(dicot) or
206:apical hook
137:germinating
607:2018-12-07
492:References
443:homologous
435:photolyase
407:Blue light
343:apoprotein
248:coleoptile
210:coleoptile
186:Etiolation
184:See also:
169:Etiolation
155:mediated.
116:etiolation
1134:1532-2548
1084:1365-3040
1034:1365-3040
966:(1): 45.
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723:: e0148.
677:1532-298X
534:1532-2548
474:hypocotyl
397:mung bean
372:PHYA-PHYE
312:known as
246:opens or
212:(monocot)
204:Distinct
165:etiolated
104:fir trees
61:frequency
1180:Category
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1042:28183154
992:26123292
941:21841916
885:16658001
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747:22303272
552:14681526
478:epicotyl
460:UV light
259:produced
112:John Ray
85:Protista
1143:3561016
983:4484705
932:3155252
867:4262772
738:3268501
686:1464706
543:1540344
482:radicle
421:mutants
347:hormone
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95:History
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36:, and
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362:genes
148:shoot
77:Fungi
26:light
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470:UV-B
466:UVR8
46:UV-B
42:UV-A
1138:PMC
1122:doi
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978:PMC
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814:PMC
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538:PMC
522:doi
518:133
349:or
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640:.
610:.
586:.
554:.
524::
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