Journal Article

Antagonistic Regulation of Leaf Flattening by Phytochrome B and Phototropin in <i>Arabidopsis thaliana</i>

Toshiaki Kozuka, Noriyuki Suetsugu, Masamitsu Wada and Akira Nagatani

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 54, issue 1, pages 69-79
Published in print January 2013 | ISSN: 0032-0781
Published online October 2012 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcs134
Antagonistic Regulation of Leaf Flattening by Phytochrome B and Phototropin in Arabidopsis thaliana

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Light is one of the most important environmental factors regulating the growth and development of leaves. As the primary photosynthetic organs, leaves have a laminar structure in many dicotyledonous plants. The regulation of leaf flatness is a key mechanism for the efficient absorption of light under low light conditions. In the present study, we demonstrated that phytochrome B (phyB) promoted the development of curled leaves. Wild-type leaves gently curled downwards under white light, whereas the phyB-deficient mutant (phyB) constitutively exhibited flatter leaves. In the wild type, leaf flattening was promoted by end-of-day far-red light (EODFR) treatment, which rapidly eliminates the active Pfr phytochrome. Interestingly, the curled-leaf phenotype in a phototropin-deficient mutant was almost completely suppressed by the phyB mutation as well as by EODFR. Thus, phototropin promotes leaf flattening by suppressing the leaf-curling activity of phyB. We examined the downstream components of phyB and phototropin to assess their antagonistic regulation of leaf flatness further. Consequently, we found that a phototropin signaling transducer, NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3), was required to promote leaf flattening in phyB. The present study provides new insights into a mechanism in which leaf flatness is regulated in response to different light environmental cues.

Keywords: Arabidospsis; Auxin; Leaf flatness; NPH3; Phototropin; Phytochrome

Journal Article.  6089 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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