臺灣博碩士論文加值系統

綜觀植物的整個發展生活史，植物的生長與發育受到相當嚴密的調控。由於植物為光合自營生物(photosynthetic autotroph)，因此光對於植物來說不僅是能量的來源，也調節了植物的整體生長與發育。植物利用多種光受器來感受環境中不同波長的光，包含負責感應藍光與UV-A的隱花色素(Cryptochrome)和植物向光素(Phototropin)，以及感應紅光與遠紅光的光敏素 (Phytochrome)。而光敏素在接受到紅光刺激之後，會由無活性的Pr構形轉變為有活性的Pfr構形進而去促進植物在光照下的生長發育。由於紅光為植物光合作用之所需，因此光敏素為影響植物生長發育最為重要的光受器，而其中又以光敏素B(phytochrome B，PHYB)最為重要。根據我們實驗室過去的實驗結果發現，POLTERGEIST(POL)與PHYB兩個蛋白質之間有著交互作用。過去的研究顯示，擬南芥(Arabidopsis thaliana)基因POLTERGEIST的突變可以逆轉因缺少任一種CLAVATA基因所造成的頂端分生組織(SAM, shoot apical meristem)膨大現象的結果看來，POL確實與CLV pathway調節有關；而由目前的研究結果得到的推論是：POL能夠調節CLV對WUS基因的抑制，而使得SAM中stem cell的數量維持穩定。缺乏POL的突變株在一般長日照光照狀況下，並不會與野生種有太大的差異，而POL與PHYB雙重突變株的性狀中，更可以觀察到 POL的突變可以逆轉PHYB突變的性狀，不僅使原本發育不良的營養葉與花莖(inflorescence)發育狀況回復正常之外，更使原本PHYB突變株之極度早開花的性狀回復到接近正常。然而，當POL的突變株在短日照的環境下生長時，則會出現產生多於一個營養葉底座(rosette)的特殊性狀。後續的實驗中也觀察到，pol-7突變株在缺乏長短日照分別的環境中，胚軸延長速率展現的不規律的性狀，以及在EODFR實驗中逆轉phyB-9突變株胚軸延長比例的性狀。綜合我們的實驗結果，以及過去對於POL及PHYB的研究，我們認為POL會調節PHYB在植物生長發育上的影響。

Throughout the life cycle of plants, the growth and developmental processes are strictly regulated. The fate of Arabidopsis stem cells are regulated by CLV genes through the repression of WUSCHEL (WUS) expression. Mutations at the CLAVATA loci (CLV1, CLV2 and CLV3) result in the enlargement of shoot apical meristems (SAM). Previous results have shown that mutations at the POL gene act as phenotypic suppressors of CLV mutations, suggesting that POLTERGEIST (POL) is involved in the regulation of CLV pathway. As the sole energy source for plants, light is the major environmental cue of plants’ development and growth. Plants use many different photoreceptors including phytochrome, cryptochrome, phototropin, and yet-unknown UV-B receptor to monitor light intensity, direction, and spectral quality. Phytochromes are red/far-red photoreceptors, and they transduce the signal to the downstream signal components after activation. Based on the study in our lab, POL interacted with PHYB, which is the major photoreceptor in charge of developmental processes under red light and far-red light. Under long-day condition, pol mutant exhibited no significant difference from wild-type, but it developed extra rosette under short-day condition. Moreover, double mutant of POL and PHYB (phyB-9pol-7) grew better than single mutant of PHYB (phyB-9). Based on these results, we hypothesize that PHYB regulates the identity and differentiation of stem cell in SAM through POLTERGEIST.
510：#1 $aThe role of Phytochrome B and POLTERGEIST in plant development

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目錄 -------------------------------------------------III
圖 目錄 -----------------------------------------------IV
表、附錄 目錄 ------------------------------------------V
中文摘要 -----------------------------------------------1
Abstract ------------------------------------------------3
緒 論 --------------------------------------------------4
材料與方法 --------------------------------------------10
結 果 -------------------------------------------------14
結論 與 討論 ------------------------------------------21
Reference -----------------------------------------------26

Boller T (2005) Peptide signalling in plant development and self/non-self perception. Curr Opin
Cell Biol 17: 116-122
Borthwick HA, Cathey HM (1962) Significance of Dark Reversion of Phytochrome in
Flowering of Short-Day Plants. Science 136: 324
Chakraborty N, Ohta M, Zhu JK (2007) Recognition of a PP2C interaction motif in several
plant protein kinases. Methods Mol Biol 365: 287-298
Chen M, Chory J, Fankhauser C (2004) Light signal transduction in higher plants. Annu Rev
Genet 38: 87-117
Chory J, Chatterjee M, Cook RK, Elich T, Fankhauser C, Li J, Nagpal P, Neff M, Pepper A,
Poole D, Reed J, Vitart V (1996) From seed germination to flowering, light controls
plant development via the pigment phytochrome. Proc Natl Acad Sci U S A 93:
12066-12071
Chou ML, Yang CH (1998) FLD interacts with genes that affect different developmental phase
transitions to regulate Arabidopsis shoot development. Plant J 15:231-242
Clark SE (1997) Organ Formation at the Vegetative Shoot Meristem. Plant Cell 9: 1067-1076
Dievart A, Clark SE (2004) LRR-containing receptors regulating plant development and
defense. Development 131: 251-261
Elich TD, Chory J (1997) Biochemical characterization of Arabidopsis wild-type and mutant
phytochrome B holoproteins. Plant Cell 9: 2271-2280
Fankhauser C, Chory J (1997) Light control of plant development. Annu Rev Cell Dev Biol 13:
203-229
Fiers M, Golemiec E, Xu J, van der Geest L, Heidstra R, Stiekema W, Liu CM (2005) The
14-amino acid CLV3, CLE19, and CLE40 peptides trigger consumption of the root
meristem in Arabidopsis through a CLAVATA2-dependent pathway. Plant Cell 17:
2542-2553
Fletcher JC, Brand U, Running MP, Simon R, Meyerowitz EM (1999) Signaling of cell fate
decisions by CLAVATA3 in Arabidopsis shoot meristems. Science 283: 1911-1914
Gross-Hardt R, Lenhard M, Laux T (2002) WUSCHEL signaling functions in interregional
communication during Arabidopsis ovule development. Genes Dev 16: 1129-1138
Halliday KJ, Koornneef M, Whitelam GC (1994) Phytochrome B and at Least One Other
Phytochrome Mediate the Accelerated Flowering Response of Arabidopsis thaliana L. to
Low Red/Far-Red Ratio. Plant Physiol 104: 1311-1315
- 27 -
Ito Y, Nakanomyo I, Motose H, Iwamoto K, Sawa S, Dohmae N, Fukuda H (2006)
Dodeca-CLE peptides as suppressors of plant stem cell differentiation. Science 313:
842-845
Kayes JM, Clark SE (1998) CLAVATA2, a regulator of meristem and organ development in
Arabidopsis. Development 125: 3843-3851
Lenhard M, Jurgens G, Laux T (2002) The WUSCHEL and SHOOTMERISTEMLESS genes
fulfil complementary roles in Arabidopsis shoot meristem regulation. Development 129:
3195-3206
Lenhard M, Laux T (2003) Stem cell homeostasis in the Arabidopsis shoot meristem is
regulated by intercellular movement of CLAVATA3 and its sequestration by CLAVATA1.
Development 130: 3163-3173
Nagy F, Schafer E (2002) Phytochromes control photomorphogenesis by differentially regulated,
interacting signaling pathways in higher plants. Annu Rev Plant Biol 53: 329-355
Ni J, Clark SE (2006) Evidence for functional conservation, sufficiency, and proteolytic
processing of the CLAVATA3 CLE domain. Plant Physiol 140: 726-733
Palecanda L, Sharrock RA (2001) Molecular and phenotypic specificity of an antisense PHYB
gene in Arabidopsis. Plant Mol Biol 46: 89-97
Parcy F (2005) Flowering: a time for integration. Int J Dev Biol 49: 585-593
Ryu JS, Kim JI, Kunkel T, Kim BC, Cho DS, Hong SH, Kim SH, Fernandez AP, Kim Y,
Alonso JM, Ecker JR, Nagy F, Lim PO, Song PS, Schafer E, Nam HG (2005)
Phytochrome-specific type 5 phosphatase controls light signal flux by enhancing
phytochrome stability and affinity for a signal transducer. Cell 120: 395-406
Schoof H, Lenhard M, Haecker A, Mayer KF, Jurgens G, Laux T (2000) The stem cell
population of Arabidopsis shoot meristems in maintained by a regulatory loop between
the CLAVATA and WUSCHEL genes. Cell 100: 635-644
Schweighofer A, Hirt H, Meskiene I (2004) Plant PP2C phosphatases: emerging functions in
stress signaling. Trends Plant Sci 9: 236-243
Sharrock RA, Clack T, Goosey L (2003) Differential activities of the Arabidopsis phyB/D/E
phytochromes in complementing phyB mutant phenotypes. Plant Mol Biol 52: 135-142
Simon R, Stahl Y (2006) Botany. Plant cells CLEave their way to differentiation. Science 313:
773-774
Song SK, Clark SE (2005) POL and related phosphatases are dosage-sensitive regulators of
meristem and organ development in Arabidopsis. Dev Biol 285: 272-284
Song SK, Lee MM, Clark SE (2006) POL and PLL1 phosphatases are CLAVATA1 signaling
intermediates required for Arabidopsis shoot and floral stem cells. Development 133:
4691-4698
- 28 -
Tamura S, Toriumi S, Saito J, Awano K, Kudo TA, Kobayashi T (2006) PP2C family
members play key roles in regulation of cell survival and apoptosis. Cancer Sci 97:
563-567
Taylor AO (1968) In Vitro Phytochrome Dark Reversion Process. Plant Physiol 43: 767-774
Williams L, Fletcher JC (2005) Stem cell regulation in the Arabidopsis shoot apical meristem.
Curr Opin Plant Biol 8: 582-586
Yakir E, Hilman D, Harir Y, Green RM (2007) Regulation of output from the plant circadian
clock. FEBS J 274: 335-345
Yu LP, Miller AK, Clark SE (2003) POLTERGEIST encodes a protein phosphatase 2C that
regulates CLAVATA pathways controlling stem cell identity at Arabidopsis shoot and
flower meristems. Curr Biol 13: 179-188
Yu LP, Simon EJ, Trotochaud AE, Clark SE (2000) POLTERGEIST functions to regulate
meristem development downstream of the CLAVATA loci. Development 127: 1661-1670