Regulation of root growth by auxin and ethylene is influenced by phosphate supply in white clover (<Emphasis Type="Italic">Trifolium repens</Emphasis> L.) |
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Authors: | Phuong T Y Dinh Marissa Roldan Susanna Leung Michael T McManus |
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Institution: | (1) Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North, New Zealand;(2) Present address: Department of Plant Pathology, Washington State University, Pullman, WA, USA;(3) AgResearch Limited, Private Bag 11008, Tennent Drive, Palmerston North, New Zealand; |
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Abstract: | The influence of P-supply on root system architecture (primary root length, number and total length of lateral roots) through
the effects of ethylene (ACC) and auxin 1-naphthylacetic acid (NAA)] has been examined in the legume white clover (Trifolium repens L.). Higher concentrations (1 and 10 μM) of ACC and NAA (100 nM) inhibited growth, while lower concentrations (100 nM ACC,
5 nM NAA) either had no effect or stimulated growth in P-sufficient (1 mM Pi) roots. In response to low (10 μM) P, a stimulation
of primary root growth, number of lateral roots and mean length of lateral roots was observed, while a super-stimulation of
these growth parameters occurred in response to subsequent 100 nM ACC treatment suggesting that the low P treatment increased
the sensitivity of the roots to ethylene. Examination of the primary roots of DR5p::GUS transformants suggests that this change in sensitivity induced by low P occurs through the promotion of auxin signalling/transport
to the root apex. These results are discussed in terms of the role of ethylene and the significance of changes in sensitivity
to the hormone in modulating root system architecture in response to low P-supply. |
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