Antagonistic regulation of leaf flattening by phytochrome B and phototropin in Arabidopsis thaliana.
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.
Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan.
Toshiaki
T
Kozuka
Noriyuki
N
Suetsugu
Masamitsu
M
Wada
Akira
A
Nagatani
D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008027:Light; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D051939:Phytochrome B / Q000235:genetics / Q000378:metabolism*; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology*; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases; D036226:Seedlings / Q000254:growth & development; D015398:Signal Transduction
D029681:Arabidopsis Proteins; C400222:NPH3 protein, Arabidopsis; C423903:PHOT2 protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; D010750:Phosphoproteins; D051939:Phytochrome B; C103646:NPH1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases