Molecular Plant Advance Access originally published online on June 7, 2007
Molecular Plant 2008 1(1):15-26; doi:10.1093/mp/ssm001
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
© The Author 2007. Published by Oxford University Press on behalf of CSPP and IPPE, SIBS, CAS.
Leaf Positioning of Arabidopsis in Response to Blue Light
a Department of Biology, Faculty of Science, Kyushu University, Ropponmatsu, Fukuoka, 810-8560 Japan
b Research and Development Center for Higher Education, Kyushu University, Ropponmatsu, Fukuoka, 810-8560 Japan
1 To whom correspondence should be addressed. E-mail kenrcb{at}mbox.nc.kyushu-u.ac.jp, fax 81-92-726-4758.
Appropriate leaf positioning is essential for optimizing photosynthesis and plant growth. However, it has not been elucidated how green leaves reach and maintain their position for capturing light. We show here the regulation of leaf positioning under blue light stimuli. When 1-week-old Arabidopsis seedlings grown under white light were transferred to red light (25 µmol m–2 s–1) for 5 d, new petioles that appeared were almost horizontal and their leaves were curled and slanted downward. However, when a weak blue light from above (0.1 µmol m–2 s–1) was superimposed on red light, the new petioles grew obliquely upward and the leaves were flat and horizontal. The leaf positioning required both phototropin1 (phot1) and nonphototropic hypocotyl 3 (NPH3), and resulted in enhanced plant growth. In an nph3 mutant, neither optimal leaf positioning nor leaf flattening by blue light was found, and blue light-induced growth enhancement was drastically reduced. When blue light was increased from 0.1 to 5 µmol m–2 s–1, normal leaf positioning and leaf flattening were induced in both phot1 and nph3 mutants, suggesting that phot2 signaling became functional and that the signaling was independent of phot1 and NPH3 in these responses. When plants were irradiated with blue light (0.1 µmol m–2 s–1) from the side and red light from above, the new leaves became oriented toward the source of blue light. When we transferred these plants to both blue light and red light from above, the leaf surface changed its orientation to the new blue light source within a few hours, whereas the petioles initially were unchanged but then gradually rotated, suggesting the plasticity of leaf positioning in response to blue light. We showed the tissue expression of NPH3 and its plasma membrane localization via the coiled-coil domain and the C-terminal region. We conclude that NPH3-mediated phototropin signaling optimizes the efficiency of light perception by inducing both optimal leaf positioning and leaf flattening, and enhances plant growth.
2 Present address: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa, Nagoya, 464-8602, Japan.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  T. Kagawa, M. Kimura, and M. Wada Blue Light-Induced Phototropism of Inflorescence Stems and Petioles is Mediated by Phototropin Family Members phot1 and phot2 Plant Cell Physiol., October 1, 2009; 50(10): 1774 - 1785. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S.-i. Inoue, T. Kinoshita, M. Matsumoto, K. I. Nakayama, M. Doi, and K.-i. Shimazaki Blue light-induced autophosphorylation of phototropin is a primary step for signaling PNAS, April 8, 2008; 105(14): 5626 - 5631. [Abstract] [Full Text] [PDF]
|
|