phot1 inhibition of ABCB19 primes lateral auxin fluxes in the shoot apex required for phototropism

Christie, J.M. et al. (2011) phot1 inhibition of ABCB19 primes lateral auxin fluxes in the shoot apex required for phototropism. PLoS Biology, 9(6), e1001076. (doi: 10.1371/journal.pbio.1001076) (PMID:21666806) (PMCID:PMC3110179)

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Abstract

It is well accepted that lateral redistribution of the phytohormone auxin underlies the bending of plant organs towards light. In monocots, photoreception occurs at the shoot tip above the region of differential growth. Despite more than a century of research, it is still unresolved how light regulates auxin distribution and where this occurs in dicots. Here, we establish a system in Arabidopsis thaliana to study hypocotyl phototropism in the absence of developmental events associated with seedling photomorphogenesis. We show that auxin redistribution to the epidermal sites of action occurs at and above the hypocotyl apex, not at the elongation zone. Within this region, we identify the auxin efflux transporter ATP-BINDING CASSETTE B19 (ABCB19) as a substrate target for the photoreceptor kinase PHOTOTROPIN 1 (phot1). Heterologous expression and physiological analyses indicate that phosphorylation of ABCB19 by phot1 inhibits its efflux activity, thereby increasing auxin levels in and above the hypocotyl apex to halt vertical growth and prime lateral fluxes that are subsequently channeled to the elongation zone by PIN-FORMED 3 (PIN3). Together, these results provide new insights into the roles of ABCB19 and PIN3 in establishing phototropic curvatures and demonstrate that the proximity of light perception and differential phototropic growth is conserved in angiosperms

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Thomson, Ms Catriona and Sullivan, Dr Stuart and Kaiserli, Dr Eirini and Ennis, Mrs Margaret and Christie, Professor John
Authors: Christie, J.M., Yang, H., Richter, G.L., Sullivan, S., Thomson, C.E., Lin, J., Titapiwatanakun, B., Ennis, M., Kaiserli, E., Lee, O.R., Adamec, J., Peer, W.A., and Murphy, A.S.
College/School:College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:PLoS Biology
Publisher:Public Library of Science
ISSN:1544-9173
ISSN (Online):1545-7885
Published Online:07 June 2011
Copyright Holders:Copyright © 2011 The Authors
First Published:First published in PLoS Biology 9(6):e1001076
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
378561Characterisation of the phot1-interacting protein AtMRD1 and its role in regulating phototropismJohn ChristieBiotechnology and Biological Sciences Research Council (BBSRC)BB/C000366/1Institute of Molecular Cell and Systems Biology