Journal Article

Radial transport of abscisic acid conjugates in maize roots: its implication for long distance stress signals

Angela Sauter and Wolfram Hartung

in Journal of Experimental Botany

Volume 51, issue 346, pages 929-935
Published in print May 2000 | ISSN: 0022-0957
Published online May 2000 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jexbot/51.346.929
Radial transport of abscisic acid conjugates in maize roots: its implication for long distance stress signals

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Conjugated, alkaline hydrolysable ABA (predominantly abscisic acid glucose ester, ABA‐GE), which is transported in the xylem from roots to shoots of Zea mays L. plants, has its origin in the root symplast rather than from soil, although it was detectable in soil solution with concentrations up to 30 nM. External ABA glucose ester cannot be dragged with the water flow across the exodermis and the endodermis because of its hydrophobic properties. Experimental evidence is presented that enzymes in the cortical apoplast cleave ABA‐GE thus releasing ABA from its conjugates. Liberated ABA can then be translocated apoplastically and symplastically to the xylem vessels. Endogenous ABA‐GE can be released from isolated cortical and stelar tissues to the surrounding media, with rates that are up to 5‐fold higher from stelar tissues than those from cortical tissues. Release of ABA‐GE is highest under conditions of inhibited ABA‐metabolism.

Keywords: ABA and ABA glucose ester; Zea mays L.; roots; xylem sap; soil.; ABA, abscisic acid; ABA‐GE, abscisic acid glucose ester; \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathit{C}_{X}^{ABA}\) \end{document}, ABA concentration in the xylem; \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathit{C}_{X}^{ABA{-}GE}\) \end{document}, ABA‐GE concentration in the xylem; JVr, volume flow per unit root surface area.

Journal Article.  3848 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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