PLANT PHYSIOLOGY , Vol 104, Issue 2 363-371, Copyright © 1994 by American Society of Plant Biologists

DEVELOPMENT AND GROWTH REGULATION

The Induction of Seed Germination in Arabidopsis thaliana Is Regulated Principally by Phytochrome B and Secondarily by Phytochrome A

T. Shinomura, A. Nagatani, J. Chory and M. Furuya
Advanced Research Laboratory, Hitachi Ltd., Hatoyama, Saitama, Japan 350-03 (T.S., M.F.)

We examined whether spectrally active phytochrome A (PhyA) and phytochrome B (PhyB) play specific roles in the induction of seed germination in Arabidopsis thaliana (L.) Heynh., using PhyA- and PhyB-null mutants, fre1-1 (A. Nagatani, J.W. Reed, J. Chory [1993] Plant Physiol 102: 269-277) and hy3-Bo64 (J. Reed, P.Nagpal, D.S. Poole, M. Furuya, J. Chory [1993] Plant Cell 5: 147-157). When dormant seeds of each genotype imbibed in the dark on aqueous agar plates, the hy3 (phyB) mutant did not germinate, whereas the fre1 (phyA) mutant germinated at a rate of 50 to 60%, and the wild type (WT) germinated at a rate of 60 to 70%. By contrast, seeds of all genotypes germinated to nearly 100% when plated in continuous irradiation with white or red light. When plated in continuous far-red light, however, frequencies of seed germination of the WT and the fre1 and hy3 mutants averaged 14, nearly 0, and 47%, respectively, suggesting that PhyB in the red-absorbing form prevents PhyA-dependent germination under continuous far-red light. When irradiated briefly with red or far-red light after imbibition for 1 h, a typical photoreversible effect on seed germination was observed in the fre1 mutant and the WT but not in the hy3 mutant. In contrast, when allowed to imbibe in the dark for 24 to 48 h and exposed to red light, the seed germination frequencies of the hy3 mutant were more than 40%. Immunoblot analyses of the mutant seeds showed that PhyB apoprotein accumulated in dormant seeds of the WT and the fre1 mutant as much as in the seeds that had imbibed. In contrast, PhyA apoprotein, although detected in etiolated seedlings grown in the dark for 5 d, was not detectable in the dormant seeds of the WT and the hy3 mutant. The above physiological and immunochemical evidence indicates that PhyB in the far-red-absorbing form was stored in the Arabidopsis seeds and resulted in germination in the dark. Hence, PhyA does not play any role in dark germination but induces germination under continuous irradiation with far-red light. Finally, we examined seeds from a signal transduction mutant, det1, and a det1/hy3 double mutant. The det1 seeds exhibited photoreversible responses of germination on aqueous agar plates, and the det1/hy3 double mutant seeds did not. Hence, DET1 is likely to act in a distinct pathway from PhyB in the photoregulation of seed germination.

This article has been cited by other articles:

				E. Oh, H. Kang, S. Yamaguchi, J. Park, D. Lee, Y. Kamiya, and G. Choi Genome-Wide Analysis of Genes Targeted by PHYTOCHROME INTERACTING FACTOR 3-LIKE5 during Seed Germination in Arabidopsis PLANT CELL, February 1, 2009; 21(2): 403 - 419. [Abstract] [Full Text] [PDF]

				P. A. Salome, Q. Xie, and C. R. McClung Circadian Timekeeping during Early Arabidopsis Development Plant Physiology, July 1, 2008; 147(3): 1110 - 1125. [Abstract] [Full Text] [PDF]

				D. H. Kim, S. Yamaguchi, S. Lim, E. Oh, J. Park, A. Hanada, Y. Kamiya, and G. Choi SOMNUS, a CCCH-Type Zinc Finger Protein in Arabidopsis, Negatively Regulates Light-Dependent Seed Germination Downstream of PIL5 PLANT CELL, May 1, 2008; 20(5): 1260 - 1277. [Abstract] [Full Text] [PDF]

				P.-H. Meng, A. Macquet, O. Loudet, A. Marion-Poll, and H. M. North Analysis of Natural Allelic Variation Controlling Arabidopsis thaliana Seed Germinability in Response to Cold and Dark: Identification of Three Major Quantitative Trait Loci Mol Plant, January 1, 2008; 1(1): 145 - 154. [Abstract] [Full Text] [PDF]

				M. V. Arana, M. J. Burgin, L. C. de Miguel, and R. A. Sanchez The very-low-fluence and high-irradiance responses of the phytochromes have antagonistic effects on germination, mannan-degrading activities, and DfGA3ox transcript levels in Datura ferox seeds J. Exp. Bot., November 15, 2007; (2007) erm256v1. [Abstract] [Full Text] [PDF]

				K. Dreher and J. Callis Ubiquitin, Hormones and Biotic Stress in Plants Ann. Bot., May 1, 2007; 99(5): 787 - 822. [Abstract] [Full Text] [PDF]

				E. Oh, S. Yamaguchi, J. Hu, J. Yusuke, B. Jung, I. Paik, H.-S. Lee, T.-p. Sun, Y. Kamiya, and G. Choi PIL5, a Phytochrome-Interacting bHLH Protein, Regulates Gibberellin Responsiveness by Binding Directly to the GAI and RGA Promoters in Arabidopsis Seeds PLANT CELL, April 1, 2007; 19(4): 1192 - 1208. [Abstract] [Full Text] [PDF]

				Y. Yamauchi, N. Takeda-Kamiya, A. Hanada, M. Ogawa, A. Kuwahara, M. Seo, Y. Kamiya, and S. Yamaguchi Contribution of Gibberellin Deactivation by AtGA2ox2 to the Suppression of Germination of Dark-Imbibed Arabidopsis thaliana Seeds Plant Cell Physiol., March 1, 2007; 48(3): 555 - 561. [Abstract] [Full Text] [PDF]

				E. Oh, J. Kim, E. Park, J.-I. Kim, C. Kang, and G. Choi PIL5, a Phytochrome-Interacting Basic Helix-Loop-Helix Protein, Is a Key Negative Regulator of Seed Germination in Arabidopsis thaliana PLANT CELL, November 1, 2004; 16(11): 3045 - 3058. [Abstract] [Full Text] [PDF]

				C. Kami, K. Mukougawa, T. Muramoto, A. Yokota, T. Shinomura, J. C. Lagarias, and T. Kohchi Complementation of phytochrome chromophore-deficient Arabidopsis by expression of phycocyanobilin:ferredoxin oxidoreductase PNAS, January 27, 2004; 101(4): 1099 - 1104. [Abstract] [Full Text] [PDF]

				K. A. Franklin and G. C. Whitelam Light signals, phytochromes and cross-talk with other environmental cues J. Exp. Bot., January 2, 2004; 55(395): 271 - 276. [Abstract] [Full Text] [PDF]

				E. Monte, J. M. Alonso, J. R. Ecker, Y. Zhang, X. Li, J. Young, S. Austin-Phillips, and P. H. Quail Isolation and Characterization of phyC Mutants in Arabidopsis Reveals Complex Crosstalk between Phytochrome Signaling Pathways PLANT CELL, September 1, 2003; 15(9): 1962 - 1980. [Abstract] [Full Text] [PDF]

				N.-J. Chung and N.-C. Paek Photoblastism and Ecophysiology of Seed Germination in Weedy Rice Agron. J., January 1, 2003; 95(1): 184 - 190. [Abstract] [Full Text] [PDF]

				R. A. Sharrock and T. Clack Patterns of Expression and Normalized Levels of the Five Arabidopsis Phytochromes Plant Physiology, September 1, 2002; 130(1): 442 - 456. [Abstract] [Full Text] [PDF]

				V. Raghavan Induction of vivipary in Arabidopsis by silique culture: implications for seed dormancy and germination Am. J. Botany, May 1, 2002; 89(5): 766 - 776. [Abstract] [Full Text] [PDF]

				M. Takano, H. Kanegae, T. Shinomura, A. Miyao, H. Hirochika, and M. Furuya Isolation and Characterization of Rice Phytochrome A Mutants PLANT CELL, March 1, 2001; 13(3): 521 - 534. [Abstract] [Full Text]

				H.-L. Hsieh, H. Okamoto, M. Wang, L.-H. Ang, M. Matsui, H. Goodman, and X. W. Deng FIN219, an auxin-regulated gene, defines a link between phytochrome A and the downstream regulator COP1 in light control of Arabidopsis development Genes & Dev., August 1, 2000; 14(15): 1958 - 1970. [Abstract] [Full Text]

				J. W. Reed, P. Nagpal, R. M. Bastow, K. S. Solomon, M. J. Dowson-Day, R. P. Elumalai, and A. J. Millar Independent Action of ELF3 and phyB to Control Hypocotyl Elongation and Flowering Time Plant Physiology, April 1, 2000; 122(4): 1149 - 1160. [Abstract] [Full Text]

				M. M. Neff, C. Fankhauser, and J. Chory Light: an indicator of time and place Genes & Dev., February 1, 2000; 14(3): 257 - 271. [Full Text]

				T. Shinomura, K. Uchida, and M. Furuya Elementary Processes of Photoperception by Phytochrome A for High-Irradiance Response of Hypocotyl Elongation in Arabidopsis Plant Physiology, January 1, 2000; 122(1): 147 - 156. [Abstract] [Full Text] [PDF]

				B. L. Montgomery, K.-C. Yeh, M. W. Crepeau, and J. C. Lagarias Modification of Distinct Aspects of Photomorphogenesis via Targeted Expression of Mammalian Biliverdin Reductase in Transgenic Arabidopsis Plants Plant Physiology, October 1, 1999; 121(2): 629 - 640. [Abstract] [Full Text]

				T. Muramoto, T. Kohchi, A. Yokota, I. Hwang, and H. M. Goodman The Arabidopsis Photomorphogenic Mutant hy1 Is Deficient in Phytochrome Chromophore Biosynthesis as a Result of a Mutation in a Plastid Heme Oxygenase PLANT CELL, March 1, 1999; 11(3): 335 - 348. [Abstract] [Full Text] [PDF]

				M. Hanumappa, L. H. Pratt, M.-M. Cordonnier-Pratt, and G. F. Deitzer A Photoperiod-Insensitive Barley Line Contains a Light-Labile Phytochrome B Plant Physiology, March 1, 1999; 119(3): 1033 - 1040. [Abstract] [Full Text]

				S. Yamaguchi, M. W. Smith, R. G. S. Brown, Y. Kamiya, and T.-p. Sun Phytochrome Regulation and Differential Expression of Gibberellin 3ß-Hydroxylase Genes in Germinating Arabidopsis Seeds PLANT CELL, December 1, 1998; 10(12): 2115 - 2126. [Abstract] [Full Text]

				J. W. Reed, R. P. Elumalai, and J. Chory Suppressors of an Arabidopsis thaliana phyB Mutation Identify Genes That Control Light Signaling and Hypocotyl Elongation Genetics, March 1, 1998; 148(3): 1295 - 1310. [Abstract] [Full Text] [PDF]

				P. Quail, M. Boylan, B. Parks, T. Short, Y Xu, and D Wagner Phytochromes: photosensory perception and signal transduction Science, May 5, 1995; 268(5211): 675 - 680. [Abstract] [PDF]