The Arabidopsis concentration-dependent influx/efflux transporter ABCB4 regulates cellular auxin levels in the root epidermis

0380687 - ÚEB 2013 RIV GB eng J - Journal Article
Kubeš, Martin - Yang, H. - Richter, G.L. - Cheng, Y. - Młodzińska, E. - Wang, X. - Blakeslee, J.J. - Carraro, N. - Petrášek, Jan - Zažímalová, Eva - Hoyerová, Klára - Ann Peer, W. - Murphy, A. S.
The Arabidopsis concentration-dependent influx/efflux transporter ABCB4 regulates cellular auxin levels in the root epidermis.
Plant Journal. Roč. 69, č. 4 (2012), s. 640-654. ISSN 0960-7412. E-ISSN 1365-313X
R&D Projects: GA MŠMT(CZ) LC06034; GA ČR(CZ) GAP305/11/0797
Institutional research plan: CEZ:AV0Z50380511
Keywords : auxin * auxin transporters * ATP-binding cassette B4
Subject RIV: EB - Genetics ; Molecular Biology
Impact factor: 6.582, year: 2012

Arabidopsis ATP-binding cassette B4 (ABCB4) is a root-localised auxin efflux transporter with reported auxin uptake activity in low auxin concentrations. Results reported here demonstrate that ABCB4 is a substrateactivated regulator of cellular auxin levels. The contribution of ABCB4 to shootward auxin movement at the root apex increases with auxin concentration, but in root hair elongation assays ABCB4-mediated uptake is evident at low concentrations as well. Uptake kinetics of ABCB4 heterologously expressed in Schizosaccharomyces pombe differed from the saturation kinetics of AUX1 as uptake converted to efflux at IAA concentrations. The concentration dependence of ABCB4 appears to be a direct effect on transporter activity, as ABCB4 expression and ABCB4 plasma membrane localisation at the root apex are relatively insensitive to changes in auxin concentration. Moreover, ABCB4 mediates uptake, but not efflux, of the synthetic auxin 2,4-D in cells lacking AUX1 activity. Results presented here suggest that 2,4-D is a non-competitive inhibitor of IAA transport by ABCB4 and indicate that ABCB4 is a target of 2,4-D herbicidal activity.
Permanent Link: http://hdl.handle.net/11104/0211331