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Root hydraulic conductance: diurnal aquaporin expression and the effects of nutrient stress

Title data

Clarkson, David T. ; Carvajal, Micaela ; Henzler, Tobias ; Waterhouse, Rosemary N. ; Smyth, Audra J. ; Cooke, David T. ; Steudle, Ernst:
Root hydraulic conductance: diurnal aquaporin expression and the effects of nutrient stress.
In: Journal of Experimental Botany. Vol. 51 (2000) Issue 342 . - pp. 61-70.
ISSN 1460-2431
DOI: https://doi.org/10.1093/jexbot/51.342.61

Abstract in another language

It has been shown that N-, P- and S-deficiencies result in major reductions of root hydraulic conductivity (Lp(r)) which may lead to lowered stomatal conductance. but the relationship between the two conductance changes is not understood. In a variety of species, Lp(r) decreases in the early stages of NO3-, H2PO42- and SO42- deprivation. These effects can be reversed in 4-24 h after the deficient nutrient is re-supplied. Diurnal fluctuations of root Lp(r) have also been found in some species, and an example of this is given for Lotus japonicus. In nutrient-sufficient wheat plants, root Lp(r) is extremely sensitive to brief treatments with HgCl2; these effects are completely reversible when Hg is removed. The low values of Lp, in N- or P-deprived roots of wheat are not affected by Hg treatments. The properties of plasma membrane (PM) vesicles from wheat roots are also affected by NO3--deprivation of the intact plants. The osmotic permeability of vesicles from N-deprived roots is much lower than that of roots adequately supplied with NO3- and is insensitive to Hg treatment. In roots of Lp(r) japonicus, gene transcripts are found which have a strong homology to those encoding the PIP1 and PIP2 aquaporins of Arabidopsis. There is a very marked diurnal cycle in the abundance of mRNAs of aquaporin gene homologues in roots of L. japonicus. The maxima and minima appear to anticipate the diurnal fluctuations in Lp(r) by 2-4 h. The temporal similarity between the cycles of the abundance of the mRNAs and root Lp(r) is most striking. The aquaporin encoded by AtPIP1 is known to have its water permeation blocked by Hg binding. The lack of Hg-sensitivity in roots and PMs from N-deprived roots provides circumstantial evidence that lowered root Lp(r) may be due to a decrease in either the activity of water channels or their density in the PM. It is concluded that roots are capable, by means completely unknown, of monitoring the nutrient content of the solution in the root apoplasm and of initiating responses that anticipate by hours or days any metabolic disturbances caused by nutrient deficiencies. It is the incoming nutrient supply that is registered as deficient, not the plant's nutrient status. At some point, close to the initiation of these responses, changes in water channel activity may be involved, but the manner in which monitoring of nutrient stress is transduced into an hydraulic response is also unknown.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER33637
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: 11 Sep 2015 06:34
Last Modified: 11 Sep 2015 06:34
URI: https://eref.uni-bayreuth.de/id/eprint/19351