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Barrowclough, David E. ; Peterson, Carol A. ; Steudle, Ernst:
Radial hydraulic conductivity along developing onion roots.
In: Journal of Experimental Botany.
Bd. 51
(2000)
Heft 344
.
- S. 547-557.
ISSN 1460-2431
DOI: https://doi.org/10.1093/jexbot/51.344.547
Abstract
Although most studies have shown that water uptake varies along the length of a developing root, there is no consistent correlation of this pattern with root anatomy. In the present study, water movement into three zones of onion roots was measured by a series of mini-potometers. Uptake was least in the youngest zone (mean hydraulic conductivity, Lp(r) = 1.5 x 10(-7) +/- 0.34 x 10(-7) m MPa-1 s (-1); +/- SE, n = 10 roots) in which the endodermis had developed only Casparian bands and the exodermis was immature. Uptake was significantly greater in the middle zone (Lp(r) = 2.4 x 10(-7) +/- 0.43 x 10(-7) m MPa-1 s(-1); +/- SE, n = 10 roots) which had a mature exodermis with both Casparian bands and suberin lamellae, and continued at this level in the oldest zone in which the endodermis had also developed suberin lamellae (Lp(r) = 2.8 x 10(-7) +/- 0.30 x 10(-7) m MPa-1 s(-1); +/- SE, n = 10 roots). Measurements of the hydraulic conductivities of individual cells (Lp) in the outer cortex using a cell pressure probe indicated that this parameter was uniform in all three zones tested (Lp = 1.3 x 10(-6) +/- 0.01 x 10(-6) m MPa-1 s(-1); +/- SE, n = 60 cells). Lp of the youngest zone was lowered by mercuric chloride treatment, indicating the involvement of mercury-sensitive water channels (aquaporins), Water flow in the older two root zones measured by mini-potometers was also inhibited by mercuric chloride, despite the demonstrated impermeability of their exodermal layers to this substance. Thus, water channels in the epidermis and/or exodermis of the older regions were especially significant for water flow. The results of this and previous studies are discussed in terms of two models. The first, which describes maize root with an immature exodermis, is the 'uniform resistance model' where hydraulic resistances are evenly distributed across the root cylinder. The second, which describes the onion root with a mature exodermis, is the 'non-uniform resistance model' where resistances can be variable and are concentrated in a certain layer(s) on the radial path.
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| Publikationsform: | Artikel in einer Zeitschrift |
|---|---|
| Begutachteter Beitrag: | Ja |
| Zusätzliche Informationen: | BAYCEER33628 |
| Institutionen der Universität: | Forschungseinrichtungen > Forschungszentren > Bayreuther Zentrum für Ökologie und Umweltforschung - BayCEER Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Biologie > Lehrstuhl Pflanzenökologie Fakultäten Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Biologie Forschungseinrichtungen Forschungseinrichtungen > Forschungszentren |
| Titel an der UBT entstanden: | Ja |
| Themengebiete aus DDC: | 500 Naturwissenschaften und Mathematik |
| Eingestellt am: | 11 Sep 2015 06:34 |
| Letzte Änderung: | 11 Sep 2015 06:34 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/19345 |