Phytochrome A mediates blue-light enhancement of second-positive phototropism in Arabidopsis

Sullivan, S., Hart, J. E., Rasch, P., Walker, C. and Christie, J. (2016) Phytochrome A mediates blue-light enhancement of second-positive phototropism in Arabidopsis. Frontiers in Plant Science, 7, 290. (doi: 10.3389/fpls.2016.00290) (PMID:27014313) (PMCID:PMC4786545)

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Abstract

Hypocotyl phototropism of etiolated Arabidopsis seedlings is primarily mediated by the blue-light receptor kinase phototropin 1 (phot1). Phot1-mediated curvature to continuous unilateral blue light irradiation (0.5 µmol m-2 s-1) is enhanced by overhead pre-treatment with red light (20 µmol m-2 s-1 for 15 min) through the action of phytochrome (phyA). Here, we show that pre-treatment with blue light is equally as effective in eliciting phototropic enhancement and is dependent on phyA. Although blue pre-treatment was sufficient to activate early phot1 signalling events, phot1 autophosphorylation in vivo was not found to be saturated, as assessed by subsequently measuring phot1 kinase activity in vitro. However, enhancement effects to red and blue pre-treatment were not observed at higher intensities of phototropic stimulation (10 µmol m-2 s-1). Phototropic enhancement to red and blue pre-treatments to 0.5 µmol m-2 s-1 unilateral blue light irradiation was also lacking in transgenic Arabidopsis where PHOT1 expression was restricted to the epidermis. Together, these findings indicate that phyA-mediated effects on phot1 signalling are restricted to low intensities of phototropic stimulation and originate from tissues other than the epidermis.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Christie, Professor John and Sullivan, Dr Stuart
Authors: Sullivan, S., Hart, J. E., Rasch, P., Walker, C., and Christie, J.
College/School:College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Frontiers in Plant Science
Publisher:Frontiers Media
ISSN (Online):1664-462X
Copyright Holders:Copyright © 2016 Sullivan, Hart, Rasch, Walker and Christie.
First Published:First published in Frontiers in Plant Science 7:290
Publisher Policy:Reproduced under a Creative Commons licence

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
581491Regulation of Auxin Fluxes Required For Phototropic GrowthJohn ChristieBiotechnology and Biological Sciences Research Council (BBSRC)BB/J016047/1RI MOLECULAR CELL & SYSTEMS BIOLOGY
659801Photoreceptor Engineering to Modulate Plant GrowthJohn ChristieBiotechnology and Biological Sciences Research Council (BBSRC)BB/M002128/1RI MOLECULAR CELL & SYSTEMS BIOLOGY