Journal Article

Systemic suppression of cluster-root formation and net P-uptake rates in <i>Grevillea crithmifolia</i> at elevated P supply: a proteacean with resistance for developing symptoms of ‘P toxicity’

Michael W. Shane and Hans Lambers

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 57, issue 2, pages 413-423
Published in print January 2006 | ISSN: 0022-0957
Published online December 2005 | e-ISSN: 1460-2431 | DOI: https://dx.doi.org/10.1093/jxb/erj004
Systemic suppression of cluster-root formation and net P-uptake rates in Grevillea crithmifolia at elevated P supply: a proteacean with resistance for developing symptoms of ‘P toxicity’

More Like This

Show all results sharing this subject:

  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

Grevillea crithmifolia R. Br. is a species of Proteaceae that is resistant to developing P-toxicity symptoms at phosphorus supplies in the root environment that induce P-toxicity symptoms in the closely related Hakea prostrata (Proteaceae). It was discovered previously that development of P-toxicity symptoms in H. prostrata is related to its low capacity to down-regulate net P-uptake rates (i.e. its low plasticity). The plasticity of net P-uptake rates and whole-plant growth responses in G. crithmifolia has now been assessed in two separate experiments: (i) a range of P, from 0 to 200 μmol P d−1, was supplied to whole root systems; (ii) using a split-root design, one root half was supplied with 0, 3, 75, or 225 μmol P d−1, while the other root half invariably received 3 μmol P d−1. Fresh mass was significantly greater in G. crithmifolia plants that had received a greater daily P supply during the pretreatments, but symptoms of P toxicity were never observed. Cluster-root growth decreased from about half the total root fresh mass when the leaf [P] was lowest (c. 0.1 mg P g−1 DM) to complete suppression of cluster-root growth when leaf [P] was 1–2 mg P g−1 DM. Split-root studies revealed that cluster-root initiation and growth, and net P-uptake rates by roots were regulated systemically, possibly by shoot P concentration. It is concluded that, in response to higher P supply, G. crithmifolia does not develop symptoms of P toxicity because of (i) greater plasticity of its net P-uptake capacity, and (ii) its greater plasticity for allocating P to growth and P storage in roots. This ecologically important difference in plasticity is most probably related to a slightly higher nutrient availability in the natural habitat of G. crithmifolia when compared with that of H. prostrata.

Keywords: Hakea prostrata; net P uptake; phosphorus toxicity; plant growth; proteoid roots; split-root design; systemic regulation

Journal Article.  7360 words.  Illustrated.

Subjects: Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content. subscribe or purchase to access all content.