Identification of the primary lesion of toxic aluminum in plant roots

Date

2015

Authors

Kopittke, P.M.
Moore, K.L.
Lombi, E.
Gianoncelli, A.
Ferguson, B.J.
Blamey, F.P.C.
Menzies, N.W.
Nicholson, T.M.
McKenna, B.A.
Wang, P.

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Journal article

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Plant Physiology, 2015; 167(4):1402-1411

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Abstract

Despite the rhizotoxicity of aluminum (Al) being identified over 100 years ago, there is still no consensus regarding themechanisms whereby root elongation rate is initially reduced in the approximately 40% of arable soils worldwide that areacidic. We used high-resolution kinematic analyses, molecular biology, rheology, and advanced imaging techniques to examinesoybean (Glycine max) roots exposed to Al. Using this multidisciplinary approach, we have conclusively shown that the primarylesion of Al is apoplastic. In particular, it was found that 75 mM Al reduced root growth after only 5 min (or 30 min at 30 mM Al),with Al being toxic by binding to the walls of outer cells, which directly inhibited their loosening in the elongation zone. Analteration in the biosynthesis and distribution of ethylene and auxin was a second, slower effect, causing both a transientdecrease in the rate of cell elongation after 1.5 h but also a longer term gradual reduction in the length of the elongationzone. These findings show the importance of focusing on traits related to cell wall composition as well as mechanismsinvolved in wall loosening to overcome the deleterious effects of soluble Al

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Data source: Supplementary data, http://www.plantphysiol.org/content/167/4/1402/suppl/DC1

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Copyright 2015 American Society of Plant Biologists

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