Bitkilerdeki Fitokrom Işık Algılayıcıları
Canlılar ışığı algılar ve tepki verir. Işık fotosentez için enerji kaynağı sağlamasının yanında, bitkilere çevrelerindeki durum hakkında da bilgi verir. Bitkilerde diğer pigmentlere ek olarak kromofor ismi verilen ışığa duyarlı pigmentler de bulunur. Günümüzde bitkilerde keşfedilen ışık algılayıcılarının sayısı 16’ya ulaşmıştır. Bunlar arasında fitokromlar, kriptokromlar, fototropinler ve UVR8 sayılabilir. Bunlardan kırmızı (R) ve kırmızı ötesi (FR) ışığı algılayan fitokromlar hem ilk keşfedilenlerdir hem de bitki büyüme ve gelişmesinde etkilidir. Fitokromlar bitkilerde tohum dinlenmesi, çimlenmesi, fide büyümesi, çiçeklenme ve yaşlanma gibi safhalarda önemli rol oynarlar. Fitokromlar öncelikle Pr formunda oluşur. Biyolojik olarak aktif olmayan Pr, gündüz kırmızı ışığı absorbe ettikten sonra aktif olan Pfr’ye dönüşür. Gündüz birikerek yüksek seviyeye ulaşan Pfr formu, dönüşüm ve parçalanma yoluyla gece azalır. Pr/Pfr oranı, bitkinin fotoperiyodun uzunluğunu algılayabilmesini sağlar. Fitokromlar ışığa göre değişken olan Tip I ve ışığa karşı göreceli olarak kararlı olan Tip II şeklinde 2 grupta incelenebilir. Diğer bir görüşe göre fitokromlarda düşük ışık şiddetine tepki veren LFR formu, çok düşük ışık şiddetine tepki veren VLFR formu, yüksek ışık şiddetine tepki veren HIR formu ve kırmızı/kırmızı ötesi oranına tepki veren R/FR formu olarak 4 grup tepki modu bulunur. Bitki fitokromunun yapısının çözülmesi, fitokromların haberleşme mekanizmasının anlaşılmasını sağlayabilecektir. Daha ekonomik, yüksek çıktılı yeni generasyon baz dizileme teknolojileri, ChIP-seq ve RNA-seq yöntemlerinin kullanımı yoluyla fitokromun genom seviyesinde tanımlanmasına yardım edebilecektir.
Phytochrome Photoreceptors in Plants
Organisms sense and respond to light. Besides light provides energy for photosynthesis, it does also give plants information about their environment. In addition to other pigments in plants, chromophores which are sensitive to light exist. Nowadays discovered photoreceptors reached at 16 in plants. Of these phytochromes, cryptochromes, phototropins, and UVR8 can be mentioned. Among others phytochromes, sense both red (R) and far-red (FR) light, are discovered first and effective in plant growth and development. Phytochromes play important roles in seed dormancy, germination, seedling growth, flowering, and maturity or senescence phases in plants. Phytochromes firstly occur in Pr form. Pr, which is not biologically active, after it absorbs red light during day time, Pr form is converted to Pfr form, which is biologically active. Pfr form reaches high level via accumulation during the day, its level decreases through conversion and disintegration during the night. Pr/Pfr ratio provides photoperiod lenght perception in plants. Phytochromes can be investigated in two groups such as Type I (labile to light) and Type II (stabile to light). According to another view, phytochromes contain four modes of action namely, LFR (low fluence response), VLFR (very low fluence response), HIR (high irradiance response), and R/FR (red/far-red ratio). Unraveling the molecular structures of plant phytochromes might provide to understand communication mechanism of the phytochromes. Using cheaper and high-throughput next nucleotide sequencing technologies, ChIP-seq, and RNA-seq methods might help to description of phytochromes in genomic level.
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- Ahmad M, Cashmore AR (1993) HY4 gene of A.thaliana
encodes a protein with characteristics of a blue-light
photoreceptor. Nature 366: 162-166.
- Aphalo PJ (2006) Light signals and the growth and
development of plants-a gentle introduction. The
Plant Photobiology Notes 1. Univ. Helsinki, Finland,
39 p.
- Auldridge ME, Forest KT (2011) Bacterial phytochromes:
more than meets the light. Crit. Rev. Biochem. Mol.
Biol. 46: 67-88.
- Borthwick HA, Hendricks SB, Parker MW, Toole EH,
Toole VK (1952) A reversible photoreaction
controlling seed germination. PNAS 38: 662-666.
- Botto JF, Sánchez RA, Whitelam GC, Casal JJ (1996)
Phytochrome A mediates the promotion of seed
germination by very low fluences of light and canopy
shade light in Arabidopsis. Plant Physiol. 110: 439-
444.
- Briggs WR (2014) Photoropism: some history, some
puzzles, and a look ahead. Plant Physiol. 164: 13-23.
- Burgie ES, Bussell AN, Walker JM, Dubiel K, Vierstra RD
(2014) Crystal structure of the photosensing module
from a red/far-red light-absorbing plant
phytochrome. PNAS 111: 10179-10184.
- Butler WL, Norris KH, Siegelman HW, Hendricks SB
(1959) Detection, assay, and preliminary purification
of the pigment controlling photosynthesis
development of plants. PNAS 45: 1703-1708.
- Cashmore AR (1997) The cryptochrome family of
photoreceptors. Plant Cell Environ. 20: 764-767.
- Chaves I, Pokorny R, Byrdin M, Hoang N, Ritz T, Brettel
K, Essen LO, van der Horst GT, Batschauer A,
Ahmad M (2011) The cryptochromes: blue light
photoreceptors in plants and animals. Annu. Rev.
Plant Biol. 62: 335-364.
- Chen M, Chory J, Fankhauser C (2004) Light signal
transduction in higher plants. Annu. Rev. Genet. 38:
87-117.
- Chory J (2010) Light signal transduction: an infinite
spectrum of posibilities. Plant J. 61: 982-991.
- Christie JM, Blackwood L, Petersen J, Sullivan S (2015)
Plant flavoprotein photoreceptors. Plant Cell Physiol.
56: 401-413.
- Deng XW, Quail PH (1999) Signalling in light-controlled
development. Cell Dev. Biol. 10: 121-129.
- Fankhauser C, Batschauer A (2016) Shadow on the plant:
A strategy to exit. Cell 164: 15-17.
- Franklin KA (2008) Shade avoidance. New Phytol. 179:
930-944.
- Franklin KA, Quail PH (2010) Phytochrome functions in
Arabidopsis development. J. Exp. Bot. 61: 11-24.
- Galvão VC, Fankhauser C (2015) Sensing the light
environment in plants: photoreceptors and early
signaling steps. Curr. Opin. Neurobiol. 34: 46-53.
- Gil P, Kircher S, Adam E, Bury E, Kozma-Bognar L,
Schäfer E, Nagy F (2000) Photocontrol of subcellular
partitioning of phytochrome-B: GFP fusion protein in
tobacco seedlings. Plant J. 22: 135-145.
- Han Y-J, Song P-S, Kim J-I (2007) Phytochrome-mediated
photomorphogenesis in plants. J. Plant Biol. 50: 230-
240.
- Hennig L, Stoddart WM, Dieterle M, Whitelam GC,
Schäfer E (2002) Phytochrome E controls lightinduced
germination of Arabidopsis. Plant Physiol.
128: 194-200.
- Hershey HP, Colbert JT, Lissemore JL, Barker RF, Quail
PH (1984) Molecular cloning of cDNA for Avena
phytochrome. PNAS 81: 2332-2336.
- Higa T, Suetsugu N, Kong SG, Wada M (2014) Actindependent
plastid movement is required for motive
force generation in directional nuclear movement in
plants. PNAS 111: 4327-4331.
- Hiltbrunner A, Viczian A, Bury E, Tscheuschler A,
Kircher S, Toth R, Honsberger A, Nagy F,
Fankhauser C, Schäfer E (2005) Nuclear
accumulation of the phytochrome A photoreceptor
requires FHY1. Curr. Biol. 15: 2125-2130.
- Ito S, Song YH, Imaizumi T (2012) LOV-domain
containing F-box proteins: light-dependent protein
degradation modules in Arabidopsis. Mol. Plant 5:
573-582.
- Jenkins GI (2014) The UV-B photoreceptor UVB8: from
structure to physiology. Plant Cell 26: 21-37.
- Jiao YL, Lau OS, Deng XW (2007) Light-regulated
transcriptional networks in higher plants. Nature
Reviews Genetics 8: 217-230
- Kami C, Lorrain S, Hornitschek P, Fankhauser C (2010)
Light-regulated plant growth and development. Curr.
Top. Dev. Biol. 91: 29-66.
- Keeton WT, Gould JL (2000) Genel Biyoloji. Cilt: 2, s:
938-940. 5.Baskı. Çev. Ed.: A. Demirsoy, İ. Türkan, E.
Gündüz. Palme Yay. Ankara.
- Kevei E, Schäfer E, Nagy F (2007) Light-regulated nucleocytoplasmic
partitioning of phytochromes. J. Exp.
Bot. 58: 3113-3124.
- Kianianmomeni A, Hallmann A (2014) Algal
photoreceptors: in vivo functions and potential
applications. Planta 239: 1-26.
- Kircher S, Kozma-Bognar L, Kim L, Adam E, Harter K,
Schäfer E, Nagy F (1999) Light quality-dependent
nuclear import of the plant photoreceptors
phytochrome A and B. Plant Cell 11: 1445-1456.
- Kong S-G, Okajima K (2016) Diverse photoreceptors
and light responses in plants. J. Plant Res. 129: 111-
114.
- Li J, Li G, Wang H, Deng XW (2011) Phytochrome
signalling mechanisms. The Arabidopsis Book 9:
e0148.
- Li F-W, Melkonian M, Rothfels CJ, Villareal JC, Stevenson
DW, Graham SW, Wong GK-S, Pryer KM, Mathews
S (2015) Phytochrome diversity in green plants and
the origin of canonical plant phytochromes. Nature
Commun. 6: 7852.
- Litts JC, Kelly JM, Lagarias JC (1983) Structure-function
studies on phytochrome: preliminary
characterization of highly purified phytochrome from
Avena sativa enriched in the 124-kilodalton species. J.
Biol. Chem. 258: 11025-11031.
- Nagatani A (2004) Light-regulated nuclear localization of
phytochromes. Curr. Opin. Plant Biol. 7: 708-711.
- Nagy F, Schäfer E (2002) Phytochromes control
photomorphogenesis by differentially regulated,
interacting signaling pathways in higher plants. Annu.
Rev. Plant Biol. 53: 329-355.
- Nozue K, Kanegae T, Imaizumi T, Fukuda S, Okamoto H,
Yeh K-C, Lagarias C, Wada M (1998) A
phytochrome from the fern Adiantum with features
of the putative photoreceptor NPH1. PNAS 95:
15826-15830.
- Quail PH (1997) An emerging molecular map of the
phytochromes. Plant Cell Environ. 20: 657-665.
- Quail PH (2010) Pytochromes. Curr. Biol. 20: R504-
R507.
- Reed JW, Nagatani A, Elich TD, Fagan M, Chory J (1994)
Phytochrome A and phytochrome B have
overlapping but distinct functions in Arabidopsis
development. Plant Physiol. 104: 1139-1149.
- Rensing SA, Sheerin DJ, Hiltbrunner A (2016)
Phytochromes: more than meets the eye. Trends
Plant Sci. 21: 543-546.
- Rockwell NC, Lagarias JC (2010) A brief history of
phytochromes. Chem. Phys. Chem. 11: 1172-1180.
- Rodriguez-Romero J, Hedtke M, Kastner C, Müller S,
Fischer R (2010) Fungi, hidden in soil or up in the air:
light makes a difference. Ann. Rev. Microbiol. 64:
585-610.
- Sakuraba Y, Jeong J, Kang M-Y, Kim J, Paek N-J, Choi G
(2014) Phytochrome-interacting transcription factors
PIF4 and PIF5 induce leaf senescence in Arabidopsis.
Nature Commun. 5: 4636.
- Schäfer E, Bowler C (2002) Phytochrome-mediated
photoperception and signal transduction in higher
plants. EMBO Reports 3: 1042-1048.
- Sharrock RA (2008) The phytochrome red/far-red
photoreceptor superfamily. Genome Biol. 9: 230.
- Sharrock RA, Quail PH (1989) Novel phytochrome
sequences in Arabidopsis thaliana: structure,
evolution, and differential expression of a plant
regulatory photoreceptor family. Genes Devel. 3:
1745-1757.
- Shikata H, Hanada K, Ushijima T, Nakashima M, Suzuki
Y, Matsushita T (2014) Phytochrome controls
alternative splicing to mediate light responses in
Arabidopsis. PNAS 111: 18781-18786.
- Shinomura T (1997) Phytochrome regulation of seed
germination. J. Plant Res. 110: 151-181.
- Shinomura T, Nagatani A, Hanzawa H, Kubota M,
Watanabe M, Furuya M (1996) Action spectra for
phytochrome A- and B-specific photoinduction of
seed germination in Arabidopsis thaliana. PNAS 93:
8129-8133.
- Siegelman HW, Turner BC, Hendricks SB (1966) The
chromophore of phytochrome. Plant Physiol. 41:
1289-1292.
- Smith H (1995) Physiological and ecological function
within the phytochrome family. Annu. Rev. Plant
Physiol. Plant Mol. Biol. 46: 289-315.
- Suetsugu N, Wada M (2013) Evolution of three LOV
blue light receptor families in green plants and
photosynthetic stramenopiles: phototropin,
ZTL/FKF!/LKP2 and aureochrome. Plant Cell Physiol.
54: 8-23.
- Taiz L, Zeiger E (2008) Bitki Fizyolojisi. 3.Baskı. Çev. Ed.:
İ. Türkan. Palme Yay., Ankara, 690 S.
- Vierstra RD, Quail PH (1983) Photochemistry of 124
kilodalton Avena phytochrome in vitro. Plant Physiol.
72: 264-267.
- Wang H, Wang H (2015) Phyochrome signaling: time to
tighten up the loose ends. Mol. Plant 8: 540-551.
- Zhou Q, Hare PD, Yang SW, Zeidler M, Huang LF, Chua
NH (2005) FHL is required for full phytochrome A
signaling and shares overlapping functions with FHY1.
Plant J. 43: 356-370.