Journal Article

Auxin transport in maize roots in response to localized nitrate supply

Jinxin Liu, Xia An, Lei Cheng, Fanjun Chen, Juan Bao, Lixing Yuan, Fusuo Zhang and Guohua Mi

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 106, issue 6, pages 1019-1026
Published in print December 2010 | ISSN: 0305-7364
Published online October 2010 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcq202
Auxin transport in maize roots in response to localized nitrate supply

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Roots typically respond to localized nitrate by enhancing lateral-root growth. Polar auxin transport has important roles in lateral-root formation and growth; however, it is a matter of debate whether or how auxin plays a role in the localized response of lateral roots to nitrate.

Methods

Treating maize (Zea mays) in a split-root system, auxin levels were quantified directly and polar transport was assayed by the movement of [3H]IAA. The effects of exogenous auxin and polar auxin transport inhibitors were also examined.

Key Results

Auxin levels in roots decreased more in the nitrate-fed compartment than in the nitrate-free compartment and nitrate treatment appeared to inhibit shoot-to-root auxin transport. However, exogenous application of IAA only partially reduced the stimulatory effect of localized nitrate, and auxin level in the roots was similarly reduced by local applications of ammonium that did not stimulate lateral-root growth.

Conclusions

It is concluded that local applications of nitrate reduced shoot-to-root auxin transport and decreased auxin concentration in roots to a level more suitable for lateral-root growth. However, alteration of root auxin level alone is not sufficient to stimulate lateral-root growth.

Keywords: Nitrate; auxin transport; lateral roots; maize; Zea mays

Journal Article.  5234 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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