OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 147/4/1750    most recent pp.108.121533v1 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 ISI 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 ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Kaneda, M. Articles by Samuels, A. L. Search for Related Content PubMed PubMed Citation Articles by Kaneda, M. Articles by Samuels, A. L. Agricola Articles by Kaneda, M. Articles by Samuels, A. L. Related Collections Membrane Trafficking

Tracking Monolignols during Wood Development in Lodgepole Pine^1,[W],[OA]

Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.K., K.H.R., J.C.T.W., B.B., A.L.S.); and Department of Wood Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (K.H.R., S.D.M.)

Secondary xylem (wood) formation in gymnosperms requires that the tracheid protoplasts first build an elaborate secondary cell wall from an array of polysaccharides and then reinforce it with lignin, an amorphous, three-dimensional product of the random radical coupling of monolignols. The objective of this study was to track the spatial distribution of monolignols during development as they move from symplasm to apoplasm. This was done by feeding [³H]phenylalanine ([³H]Phe) to dissected cambium/developing wood from lodgepole pine (Pinus contorta var latifolia) seedlings, allowing uptake and metabolism, then rapidly freezing the cells and performing autoradiography to detect the locations of the monolignols responsible for lignification. Parallel experiments showed that radioactivity was incorporated into polymeric lignin and a methanol-soluble pool that was characterized by high-performance liquid chromatography. [³H]Phe was incorporated into expected lignin precursors, such as coniferyl alcohol and p-coumaryl alcohol, as well as pinoresinol. Coniferin, the glucoside of coniferyl alcohol, was detected by high-performance liquid chromatography but was not radioactively labeled. With light microscopy, radiolabeled phenylpropanoids were detected in the rays as well as the tracheids, with the two cell types showing differential sensitivity to inhibitors of protein translation and phenylpropanoid metabolism. Secondary cell walls of developing tracheids were heavily labeled when incubated with [³H]Phe. Inside the cell, cytoplasm was most strongly labeled followed by Golgi and low-vacuole label. Inhibitor studies suggest that the Golgi signal could be attributed to protein, rather than phenylpropanoid, origins. These data, produced with the best microscopy tools that are available today, support a model in which unknown membrane transporters, rather than Golgi vesicles, export monolignols.

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: A. Lacey Samuels (lsamuels{at}interchange.ubc.ca).

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.108.121533

^* Corresponding author; e-mail lsamuels{at}interchange.ubc.ca.

Received April 25, 2008; accepted May 18, 2008; published June 11, 2008.

Related articles in Plant Physiol.:

On the Inside

Peter V. Minorsky
Plant Physiol. 2008 147: 1761-1762. [Full Text]  

This article has been cited by other articles:

				K. Marjamaa, E. M. Kukkola, and K. V. Fagerstedt The role of xylem class III peroxidases in lignification J. Exp. Bot., February 1, 2009; 60(2): 367 - 376. [Abstract] [Full Text] [PDF]

				A. Y. Cheung and S. C. de Vries Membrane Trafficking: Intracellular Highways and Country Roads Plant Physiology, August 1, 2008; 147(4): 1451 - 1453. [Full Text] [PDF]