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Localization of the auxin permease AUX1 suggests two functionally distinct hormone transport pathways operate in the Arabidopsis root apex

Localization of the auxin permease AUX1 suggests two functionally distinct hormone transport pathways operate in the Arabidopsis root apex
Localization of the auxin permease AUX1 suggests two functionally distinct hormone transport pathways operate in the Arabidopsis root apex
Auxins represent an important class of plant hormone that regulate plant development. Plants use specialized carrier proteins to transport the auxin indole-3-acetic acid (IAA) to target tissues. To date, efflux carrier-mediated polar auxin transport has been assumed to represent the sole mode of long distance IAA movement. Localization of the auxin permease AUX1 in the Arabidopsis root apex has revealed a novel phloem-based IAA transport pathway. AUX1, asymmetrically localized to the plasma membrane of root protophloem cells, is proposed to promote the acropetal, post-phloem movement of auxin to the root apex. MS analysis shows that IAA accumulation in aux1 mutant root apices is impaired, consistent with an AUX1 phloem unloading function. AUX1 localization to columella and lateral root cap tissues of the Arabidopsis root apex reveals that the auxin permease regulates a second IAA transport pathway. Expression studies using an auxin-regulated reporter suggest that AUX1 is necessary for root gravitropism by facilitating basipetal auxin transport to distal elongation zone tissues.
0890-9369
2648-2653
Swarup, Ranjan
01a7c8f9-9165-4aa8-8d7f-f84879894f97
Friml, Jirí
971a1dbb-e254-423c-8d5f-b6ceaa2ab36e
Marchant, Alan
3e54d51c-53b0-4df0-b428-2e73b071ee8e
Ljung, Karin
f5f984c4-e3a9-4283-9e4a-5410b7035ab8
Sandberg, Goran
5807cf0b-1e87-47d5-bd3f-d67f6ac83bf9
Palme, Klaus
3ca44a17-1d78-489d-b442-92f0d9de16e7
Bennett, Malcolm
1c8bd66c-2a22-49f0-a8e6-baebb9b7d42c
Swarup, Ranjan
01a7c8f9-9165-4aa8-8d7f-f84879894f97
Friml, Jirí
971a1dbb-e254-423c-8d5f-b6ceaa2ab36e
Marchant, Alan
3e54d51c-53b0-4df0-b428-2e73b071ee8e
Ljung, Karin
f5f984c4-e3a9-4283-9e4a-5410b7035ab8
Sandberg, Goran
5807cf0b-1e87-47d5-bd3f-d67f6ac83bf9
Palme, Klaus
3ca44a17-1d78-489d-b442-92f0d9de16e7
Bennett, Malcolm
1c8bd66c-2a22-49f0-a8e6-baebb9b7d42c

Swarup, Ranjan, Friml, Jirí, Marchant, Alan, Ljung, Karin, Sandberg, Goran, Palme, Klaus and Bennett, Malcolm (2001) Localization of the auxin permease AUX1 suggests two functionally distinct hormone transport pathways operate in the Arabidopsis root apex. Genes & Development, 15 (20), 2648-2653. (doi:10.1101/gad.210501).

Record type: Article

Abstract

Auxins represent an important class of plant hormone that regulate plant development. Plants use specialized carrier proteins to transport the auxin indole-3-acetic acid (IAA) to target tissues. To date, efflux carrier-mediated polar auxin transport has been assumed to represent the sole mode of long distance IAA movement. Localization of the auxin permease AUX1 in the Arabidopsis root apex has revealed a novel phloem-based IAA transport pathway. AUX1, asymmetrically localized to the plasma membrane of root protophloem cells, is proposed to promote the acropetal, post-phloem movement of auxin to the root apex. MS analysis shows that IAA accumulation in aux1 mutant root apices is impaired, consistent with an AUX1 phloem unloading function. AUX1 localization to columella and lateral root cap tissues of the Arabidopsis root apex reveals that the auxin permease regulates a second IAA transport pathway. Expression studies using an auxin-regulated reporter suggest that AUX1 is necessary for root gravitropism by facilitating basipetal auxin transport to distal elongation zone tissues.

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Published date: 1 October 2001

Identifiers

Local EPrints ID: 55945
URI: http://eprints.soton.ac.uk/id/eprint/55945
ISSN: 0890-9369
PURE UUID: ea916270-c641-4424-84db-9851e41002d8

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Date deposited: 08 Aug 2008
Last modified: 15 Mar 2024 10:58

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Contributors

Author: Ranjan Swarup
Author: Jirí Friml
Author: Alan Marchant
Author: Karin Ljung
Author: Goran Sandberg
Author: Klaus Palme
Author: Malcolm Bennett

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