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Aluminum-Dependent Root-Growth Inhibition in Arabidopsis Results from AtATR-Regulated Cell-Cycle Arrest

Aluminum (Al) toxicity is a global problem severely limiting agricultural productivity in acid-soil regions comprising upwards of 50% of the world's arable land [1, 2]. Although Al-exclusion mechanisms have been intensively studied [3–9], little is known about tolerance to internalized Al, whic...

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Published in:Current biology 2008-10, Vol.18 (19), p.1495-1500
Main Authors: Rounds, Megan A., Larsen, Paul B.
Format: Article
Language:English
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Summary:Aluminum (Al) toxicity is a global problem severely limiting agricultural productivity in acid-soil regions comprising upwards of 50% of the world's arable land [1, 2]. Although Al-exclusion mechanisms have been intensively studied [3–9], little is known about tolerance to internalized Al, which is predicted to be mechanistically complex because of the plethora of predicted cellular targets for Al 3+ [2, 10]. An Arabidopsis mutant with Al hypersensitivity, als3-1, was found to represent a lesion in a phloem and root-tip-localized factor similar to the bacterial ABC transporter ybbm, with ALS3 likely responsible for Al transfer from roots to less-sensitive tissues [10–12]. To identify mutations that enhance mechanisms of Al resistance or tolerance, a suppressor screen for mutants that mask the Al hypersensitivity of als3-1 was performed [13]. Two allelic suppressors conferring increased Al tolerance were found to represent dominant-negative mutations in a factor required for monitoring DNA integrity, AtATR [14–17]. From this work, Al-dependent root-growth inhibition primarily arises from DNA damage coupled with AtATR-controlled blockage of cell-cycle progression and terminal differentiation because of loss of the root-quiescent center, with mutations that prevent response to this damage resulting in quiescent-center maintenance and sustained vigorous growth in an Al-toxic environment.
ISSN:0960-9822
1879-0445
DOI:10.1016/j.cub.2008.08.050