ABA plays a central role in mediating the regulatory effects of nitrate on root branching in Arabidopsis.
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.
Signora
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Division of Crop Performance and Improvement, IACR-Rothamsted, Harpenden, Hertfordshire, AL5 JQ, UK.
De Smet
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Foyer
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Zhang
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D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D009154:Mutation; D009566:Nitrates / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D015398:Signal Transduction
D009566:Nitrates; D000040:Abscisic Acid