JXB Advance Access published online on October 3, 2008
Journal of Experimental Botany, doi:10.1093/jxb/ern231
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
© 2008 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details)
RESEARCH PAPER |
The nature of floral signals in Arabidopsis. I. Photosynthesis and a far-red photoresponse independently regulate flowering by increasing expression of FLOWERING LOCUS T (FT)
CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
To whom correspondence should be addressed. E-mail: rod.king{at}csiro.au
Arabidopsis flowers in long day (LD) in response to signals transported from the photoinduced leaf to the shoot apex. These LD signals may include protein of the gene FLOWERING LOCUS T (FT) while in short day (SD) with its slower flowering, signalling may involve sucrose and gibberellin. Here, it is shown that after 5 weeks growth in SD, a single LD up-regulated leaf blade expression of FT and CONSTANS (CO) within 4–8 h, and flowers were visible within 2–3 weeks. Plants kept in SDs were still vegetative 7 weeks later. This LD response was blocked in ft-1 and a co mutant. Exposure to different LD light intensities and spectral qualities showed that two LD photoresponses are important for up-regulation of FT and for flowering. Phytochrome is effective at a low intensity from far-red (FR)-rich incandescent lamps. Independently, photosynthesis is active in an LD at a high intensity from red (R)-rich fluorescent lamps. The photosynthetic role of a single high light LD is demonstrated here by the blocking of the flowering and FT increase on removal of atmospheric CO2 or by decreasing the LD light intensity by 10-fold. These conditions also reduced leaf blade sucrose content and photosynthetic gene expression. An SD light integral matching that in a single LD was not effective for flowering, although there was reasonable FT-independent flowering after 12 SD at high light. While a single photosynthetic LD strongly amplified FT expression, the ability to respond to the LD required an additional but unidentified photoresponse. The implications of these findings for studies with mutants and for flowering in natural conditions are discussed.
Key words: Arabidopsis, CONSTANS, far-red light, flowering, FT, long day, photosynthesis, sucrose
* These authors contributed equally to this work.
Present address: National Institute of Floricultural Science (NIFS), Tsukuba, 305-8519 Japan.
Present address: The Robert H. Smith Institute for Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel.
Received 9 June 2008; Revised 25 July 2008 Accepted 5 August 2008
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  S. Pouteau and C. Albertini The significance of bolting and floral transitions as indicators of reproductive phase change in Arabidopsis J. Exp. Bot., August 1, 2009; 60(12): 3367 - 3377. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. A. Warner, P. J. Rudall, and M. W. Frohlich Environmental control of sepalness and petalness in perianth organs of waterlilies: a new Mosaic Theory for the evolutionary origin of a differentiated perianth J. Exp. Bot., August 1, 2009; 60(12): 3559 - 3574. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Compiled by, F. Tooke, T. Chiurugwi, and N. Battey Flowering Newsletter bibliography for 2008 J. Exp. Bot., June 23, 2009; (2009) erp154v1. [Full Text] [PDF]
|
|
|
|
|
|
E. Mutasa-Gottgens and P. Hedden Gibberellin as a factor in floral regulatory networks J. Exp. Bot., May 1, 2009; 60(7): 1979 - 1989. [Abstract] [Full Text] [PDF]
|
|