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)

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: Kaiserli, Dr Eirini and Thomson, Ms Catriona and Christie, Professor John and Sullivan, Dr Stuart and Ennis, Mrs Margaret
• 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 > School of Molecular Biosciences
• 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

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
37856	1	Characterisation of the phot1-interacting protein AtMRD1 and its role in regulating phototropism	John Christie	Biotechnology and Biological Sciences Research Council (BBSRC)	BB/C000366/1	Institute of Molecular Cell and Systems Biology