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ENVIRONMENTAL STRESS AND ADAPTATION TO STRESS

Response of the Leaf Cell Wall to Desiccation in the Resurrection Plant Myrothamnus flabellifolius¹

Department of Molecular and Cellular Biology, University of Cape Town, Rondebosch 7701, South Africa (J.P.M., G.G.L., W.F.B., J.M.F.); and Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6037, Institut Fédératif de Recherche Multidisciplinaire sur les Peptides 23, Centre Commun de Microscopie Electronique, Université de Rouen, 76821 Mont Saint Aignan cedex, France (E.N.-O., L.C., P.L., A.D.)

The Myrothamnus flabellifolius leaf cell wall and its response to desiccation were investigated using electron microscopic, biochemical, and immunocytochemical techniques. Electron microscopy revealed desiccation-induced cell wall folding in the majority of mesophyll and epidermal cells. Thick-walled vascular tissue and sclerenchymous ribs did not fold and supported the surrounding tissue, thereby limiting the extent of leaf shrinkage and allowing leaf morphology to be rapidly regained upon rehydration. Isolated cell walls from hydrated and desiccated M. flabellifolius leaves were fractionated into their constituent polymers and the resulting fractions were analyzed for monosaccharide content. Significant differences between hydrated and desiccated states were observed in the water-soluble buffer extract, pectin fractions, and the arabinogalactan protein-rich extract. A marked increase in galacturonic acid was found in the alkali-insoluble pectic fraction. Xyloglucan structure was analyzed and shown to be of the standard dicotyledonous pattern. Immunocytochemical analysis determined the cellular location of the various epitopes associated with cell wall components, including pectin, xyloglucan, and arabinogalactan proteins, in hydrated and desiccated leaf tissue. The most striking observation was a constitutively present high concentration of arabinose, which was associated with pectin, presumably in the form of arabinan polymers. We propose that the arabinan-rich leaf cell wall of M. flabellifolius possesses the necessary structural properties to be able to undergo repeated periods of desiccation and rehydration.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: George G. Lindsey (lindsey{at}science.uct.ac.za).

Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.106.077701.

^* Corresponding author; e-mail lindsey{at}science.uct.ac.za; fax 27–21–689–7573.

Received January 24, 2006; returned for revision March 14, 2006; accepted March 22, 2006.

This article has been cited by other articles:

				J. P. Moore, G. G. Lindsey, J. M. Farrant, and W. F. Brandt An Overview of the Biology of the Desiccation-tolerant Resurrection Plant Myrothamnus flabellifolia Ann. Bot., February 1, 2007; 99(2): 211 - 217. [Abstract] [Full Text] [PDF]