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Shoot-derived auxin is essential for early lateral root emergence in Arabidopsis seedlings

Shoot-derived auxin is essential for early lateral root emergence in Arabidopsis seedlings
Shoot-derived auxin is essential for early lateral root emergence in Arabidopsis seedlings
Lateral root formation is profoundly affected by auxins. Here we present data which indicate that light influences the formation of indole-3-acetic acid (IAA) in germinating Arabidopsis seedlings. IAA transported from the developing leaves to the root system is detectable as a short-lived pulse in the roots and is required for the emergence of the lateral root primordia (LRP) during early seedling development. LRP emergence is inhibited by the removal of apical tissues prior to detection of the IAA pulse in the root, but this treatment has minimal effects on LRP initiation. Our results identify the first developing true leaves as the most likely source for the IAA required for the first emergence of the LRP, as removal of cotyledons has only a minor effect on LRP emergence in contrast to removal of the leaves. A basipetal IAA concentration gradient with high levels of IAA in the root tip appears to control LRP initiation, in contrast to their emergence. A significant increase in the ability of the root system to synthesize IAA is observed 10 days after germination, and this in turn is reflected in the reduced dependence of the lateral root emergence on aerial tissue-derived auxin at this stage. We propose a model for lateral root formation during early seedling development that can be divided into two phases: (i) an LRP initiation phase dependent on a root tip-localized IAA source, and (ii) an LRP emergence phase dependent on leaf-derived IAA up to 10 days after germination.
auxin, IAA, lateral root, Arabidopsis thaliana
0960-7412
325-332
Bhalerao, Rishikesh P.
7d29fc1b-920b-4f81-b805-14b4a45b7bb0
Eklof, Jan
683699e6-2ab1-4c18-abd7-9e9105c8fb95
Ljung, Karin
f5f984c4-e3a9-4283-9e4a-5410b7035ab8
Marchant, Alan
3e54d51c-53b0-4df0-b428-2e73b071ee8e
Bennett, Malcolm
1c8bd66c-2a22-49f0-a8e6-baebb9b7d42c
Sandberg, Goran
5807cf0b-1e87-47d5-bd3f-d67f6ac83bf9
Bhalerao, Rishikesh P.
7d29fc1b-920b-4f81-b805-14b4a45b7bb0
Eklof, Jan
683699e6-2ab1-4c18-abd7-9e9105c8fb95
Ljung, Karin
f5f984c4-e3a9-4283-9e4a-5410b7035ab8
Marchant, Alan
3e54d51c-53b0-4df0-b428-2e73b071ee8e
Bennett, Malcolm
1c8bd66c-2a22-49f0-a8e6-baebb9b7d42c
Sandberg, Goran
5807cf0b-1e87-47d5-bd3f-d67f6ac83bf9

Bhalerao, Rishikesh P., Eklof, Jan, Ljung, Karin, Marchant, Alan, Bennett, Malcolm and Sandberg, Goran (2002) Shoot-derived auxin is essential for early lateral root emergence in Arabidopsis seedlings. The Plant Journal, 29 (3), 325-332. (doi:10.1046/j.0960-7412.2001.01217.x).

Record type: Article

Abstract

Lateral root formation is profoundly affected by auxins. Here we present data which indicate that light influences the formation of indole-3-acetic acid (IAA) in germinating Arabidopsis seedlings. IAA transported from the developing leaves to the root system is detectable as a short-lived pulse in the roots and is required for the emergence of the lateral root primordia (LRP) during early seedling development. LRP emergence is inhibited by the removal of apical tissues prior to detection of the IAA pulse in the root, but this treatment has minimal effects on LRP initiation. Our results identify the first developing true leaves as the most likely source for the IAA required for the first emergence of the LRP, as removal of cotyledons has only a minor effect on LRP emergence in contrast to removal of the leaves. A basipetal IAA concentration gradient with high levels of IAA in the root tip appears to control LRP initiation, in contrast to their emergence. A significant increase in the ability of the root system to synthesize IAA is observed 10 days after germination, and this in turn is reflected in the reduced dependence of the lateral root emergence on aerial tissue-derived auxin at this stage. We propose a model for lateral root formation during early seedling development that can be divided into two phases: (i) an LRP initiation phase dependent on a root tip-localized IAA source, and (ii) an LRP emergence phase dependent on leaf-derived IAA up to 10 days after germination.

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More information

Published date: 13 February 2002
Keywords: auxin, IAA, lateral root, Arabidopsis thaliana

Identifiers

Local EPrints ID: 55924
URI: http://eprints.soton.ac.uk/id/eprint/55924
ISSN: 0960-7412
PURE UUID: ed9e3db3-bc34-4833-b842-1a036a01694a

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Date deposited: 06 Aug 2008
Last modified: 15 Mar 2024 10:58

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Contributors

Author: Rishikesh P. Bhalerao
Author: Jan Eklof
Author: Karin Ljung
Author: Alan Marchant
Author: Malcolm Bennett
Author: Goran Sandberg

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