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Reduced water relocation of Arabidopsis pip2 aquaporin knockout mutants into rosette leaves using a novel non-invasive approach.

Vortrag: Plant Research in the Light of Climate Change - The benefits of environmental simulation, 15. April 2010, Munich, Germany. (2010)
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Aquaporins are intrinsic membrane proteins, which facilitate water exchange across cellular membranes. In plants numerous isoforms have been found in several membrane compartments. PIP (plasma membrane intrinsic proteins) are localized to the plasma membrane and thought to be involved in cellular water exchange, but also in routes of long distance transport depending on transcellular paths and in distribution within tissue. One tool to assess the role of individual isoforms is provided by pip knockout mutants in the model plant Arabidopsis thaliana. With regard to water relations several invasive techniques like root exudation or pressure probes may be applied. In contrast to these studies, in this work the source δD content of the medium of hydroponically grown Arabidopsis was artificially raised and the kinetics of δD increase in the aerial parts recorded until a new, enhanced δD equilibrium was reached. Leaf water possesses an elevated 2H (δD) steady state content due to the retarded evaporation and diffusion of water molecules containing the heavier isotopes. A basal version of the enrichment models was modified to establish an equation, which could be fitted to measured leaf δD values during uptake kinetics and allowed to estimate the relative water flux qleaf into the rosette leaves. Growth conditions providing controlled temperature, irradiation and ambient humidity are a prerequisite for such an experiment, since these environmental parameters strongly influence water uptake. In two Arabidopsis pip2;1 and pip2;2 knockout plants assayed qleaf was significantly reduced by about 20%. The organ and cellular expression patterns of both genes imply that changes in root hydraulic conductivity as well as in leaf water uptake and distribution were contributing in an integrated fashion to this reduced flux in intact plants. Thus, this novel approach offers a quasi non-invasive tool for an integrated analysis of plant water relations.
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Publication type Other: Lecture
Conference Title Plant Research in the Light of Climate Change - The benefits of environmental simulation
Conference Date 15. April 2010
Conference Location Munich, Germany