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Water uptake by roots of maize and sunflower affects the radial transport of abscisic acid and its concentration in the xylem

Title data

Freundl, Elenor ; Steudle, Ernst ; Hartung, Wolfram:
Water uptake by roots of maize and sunflower affects the radial transport of abscisic acid and its concentration in the xylem.
In: Planta. Vol. 207 (1998) Issue 1 . - pp. 8-19.
ISSN 0032-0935
DOI: https://doi.org/10.1007/s004250050450

Abstract in another language

The radial movement of cis-abscisic acid (ABA) has been investigated in young excised roots of Zea mays L. and Helianthus annuus I,. which were grown hydroponically. In addition to the symplastic path, ABA was largely translocated across the root apoplast by solvent drag with the water in the transpiration stream. On the apoplastic path ABA may even cross the endodermis. Depending on the ABA concentration of the medium (range: 5-500 nM) and in the root apoplast, the solvent-drag component of the flow of ABA counteracted the dilution of ABA in the xylem caused by transpirational water how. Acidification of the rhizosphere and of the root apoplast increased the apoplastic transport component. In sunflower, the apoplastic flow of ABA was significantly weaker than in maize roots. This was also indicated by the larger apparent reflection coefficient (sigma(ABA)) of sunflower roots for ABA (sunflower: sigma(ABA) = 0.97 +/- 0.02, n = 6 roots; maize: sigma(ABA) = 0.68 +/- 0.06, n = 6 roots; +/-SD). For both species, sigma(ABA) was smaller than unity. Root reflection coefficients were affected by factors such as pH, ABA concentration of the medium, and by the suction force applied to excised root systems. Due to the complex composite structure of the permeation barrier in the root, the reflection coefficient estimated from solvent drag is also complex. Since unstirred layers affected the absolute value of the reflection coefficient, sigma(ABA) has been termed 'apparent'. It is concluded that the pH and ABA concentration of the soil solution as well as the transpiration rate (suction force) modify the intensity of the root-to-shoot signal which is influenced by an apoplastic bypass flow of ABA. The latter may be substantially affected by the existence of Casparian bands in the exodermis, which were lacking in the roots studied in this paper.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER33651
Institutions of the University: Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Biology > Chair Plant Ecology
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Biology
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 24 Sep 2015 09:38
Last Modified: 24 Sep 2015 09:38
URI: https://eref.uni-bayreuth.de/id/eprint/19728