This Article Full Text Full Text (PDF) All Versions of this Article: 133/2/630    most recent pp.103.027797v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in Plant Physiol. Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (21) Citing Articles via Google Scholar Google Scholar Articles by Sakr, S. Articles by Chrispeels, M. J. Search for Related Content PubMed PubMed Citation Articles by Sakr, S. Articles by Chrispeels, M. J. Agricola Articles by Sakr, S. Articles by Chrispeels, M. J.

ENVIRONMENTAL STRESS AND ADAPTATION

Plasma Membrane Aquaporins Are Involved in Winter Embolism Recovery in Walnut Tree¹

Unité Mixte de Recherche 547–Physiologie Integreé de d'Arbre Fruitier Institut National de la Recherche Agronomique, Site des Cézeaux, Université Blaise Pascal, 24 Avenue des Landais, 63177Aubière cedex, France (S.S., G.A., K.M., M.D., A.G., J.-L.J.); Division of Biological Sciences, University of California San Diego, La Jolla, California 92093–0116 (R.M., M.J.C.); and Unité Mixte de Recherche Centre National de la Recherche Scientifique 6161, Bâtiment Botanique, 40 Avenue Recteur Pineau, 86022 Poitiers, France (P.F.-L.)

In perennial plants, freeze-thaw cycles during the winter months can induce the formation of air bubbles in xylem vessels, leading to changes in their hydraulic conductivity. Refilling of embolized xylem vessels requires an osmotic force that is created by the accumulation of soluble sugars in the vessels. Low water potential leads to water movement from the parenchyma cells into the xylem vessels. The water flux gives rise to a positive pressure essential for the recovery of xylem hydraulic conductivity. We investigated the possible role of plasma membrane aquaporins in winter embolism recovery in walnut (Juglans regia). First, we established that xylem parenchyma starch is converted to sucrose in the winter months. Then, from a xylem-derived cDNA library, we isolated two PIP2 aquaporin genes (JrPIP2,1 and JrPIP2,2) that encode nearly identical proteins. The water channel activity of the JrPIP2,1 protein was demonstrated by its expression in Xenopus laevis oocytes. The expression of the two PIP2 isoforms was investigated throughout the autumn-winter period. In the winter period, high levels of PIP2 mRNA and corresponding protein occurred simultaneously with the rise in sucrose. Furthermore, immunolocalization studies in the winter period show that PIP2 aquaporins were mainly localized in vessel-associated cells, which play a major role in controlling solute flux between parenchyma cells and xylem vessels. Taken together, our data suggest that PIP2 aquaporins could play a role in water transport between xylem parenchyma cells and embolized vessels.

¹ This work was supported in part by the Ministère de la Recherche et de l'Education Nationale and Institut National de la Recherche Agronomique (to S.S., M.D., A.G., and J.-L.J.) and by the U.S. Department of Agriculture, National Research Initiative Competitive Grants Program (to R.M. and M.J.C.).

² Present address: Station de Recherche Agronomique, Institut National de le Recherche Agronomique-Centre de Coopération Internationale en Recherche Agronomique pour le Développement, 20230 San Giuliano, France.

^* Corresponding author; e-mail Soulaiman.Sakr{at}piaf.univbpclermont.fr; fax 33–4–73–40–79–16.

Received May 30, 2003; returned for revision June 30, 2003; accepted June 30, 2003.

Related articles in Plant Physiol.:

Peter V. Minorsky
Plant Physiol. 2003 133: 425-426. [Full Text]  

This article has been cited by other articles:

				A. Dusotoit-Coucaud, N. Brunel, P. Kongsawadworakul, U. Viboonjun, A. Lacointe, J.-L. Julien, H. Chrestin, and S. Sakr Sucrose importation into laticifers of Hevea brasiliensis, in relation to ethylene stimulation of latex production Ann. Bot., June 30, 2009; (2009) mcp150v1. [Abstract] [Full Text] [PDF]

				G.-W. Li, M.-H. Zhang, W.-M. Cai, W.-N. Sun, and W.-A. Su Characterization of OsPIP2;7, a Water Channel Protein in Rice Plant Cell Physiol., December 1, 2008; 49(12): 1851 - 1858. [Abstract] [Full Text] [PDF]

				H. Cochard, J.-S. Venisse, T. S. Barigah, N. Brunel, S. Herbette, A. Guilliot, M. T. Tyree, and S. Sakr Putative Role of Aquaporins in Variable Hydraulic Conductance of Leaves in Response to Light Plant Physiology, January 1, 2007; 143(1): 122 - 133. [Abstract] [Full Text] [PDF]

				E. M. Herman, K. Rotter, R. Premakumar, G Elwinger, R. Bae, L. Ehler-King, S. Chen, and D. P. Livingston III Additional freeze hardiness in wheat acquired by exposure to -3 {degrees}C is associated with extensive physiological, morphological, and molecular changes J. Exp. Bot., November 1, 2006; 57(14): 3601 - 3618. [Abstract] [Full Text] [PDF]