ABA plays a central role in mediating the regulatory effects of nitrate on root branching in Arabidopsis

Authors

  • Laurent Signora,

    1. 1 Division of Crop Performance and Improvement, IACR-Rothamsted, Harpenden, Hertfordshire, AL5 2 JQ, UK, and2Centre for Plant Sciences, Leeds Institute of Biotechnology and Agriculture (LIBA), School of Biology, University of Leeds, Leeds, LS2 9JT, UK
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  • 1,2 Ive De Smet,

    1. 1 Division of Crop Performance and Improvement, IACR-Rothamsted, Harpenden, Hertfordshire, AL5 2 JQ, UK, and2Centre for Plant Sciences, Leeds Institute of Biotechnology and Agriculture (LIBA), School of Biology, University of Leeds, Leeds, LS2 9JT, UK
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    • Present address: Vlaams Instituut voor Biotechnologie, Department of Genetics, University of Gent, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium.

  • 2, Christine H Foyer,

    1. 1 Division of Crop Performance and Improvement, IACR-Rothamsted, Harpenden, Hertfordshire, AL5 2 JQ, UK, and2Centre for Plant Sciences, Leeds Institute of Biotechnology and Agriculture (LIBA), School of Biology, University of Leeds, Leeds, LS2 9JT, UK
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  • and 1 Hanma Zhang 2,

    Corresponding author
    1. 1 Division of Crop Performance and Improvement, IACR-Rothamsted, Harpenden, Hertfordshire, AL5 2 JQ, UK, and2Centre for Plant Sciences, Leeds Institute of Biotechnology and Agriculture (LIBA), School of Biology, University of Leeds, Leeds, LS2 9JT, UK
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For correspondence (fax +44 (0) 113 233 2835; e-mail h.m.zhang@leeds.ac.uk).

Summary

The formation of lateral roots (LR) is a major post-embryonic developmental event in plants. In Arabidopsis thaliana, LR development is inhibited by high concentrations of NO3. Here we present strong evidence that ABA plays an important role in mediating the effects of NO3 on LR formation. Firstly, the inhibitory effect of NO3 is significantly reduced in three ABA insensitive mutants, abi4-1, abi4-2 and abi5-1, but not in abi1-1, abi2-1 and abi3-1. Secondly, inhibition by NO3 is significantly reduced, but not completely abolished, in four ABA synthesis mutants, aba1-1, aba2-3, aba2-4 and aba3-2. These results indicate that there are two regulatory pathways mediating the inhibitory effects of NO3 in A. thaliana roots. One pathway is ABA-dependent and involves ABI4 and ABI5, whereas the second pathway is ABA-independent. In addition, ABA also plays a role in mediating the stimulation of LR elongation by local NO3 applications.

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