The mur2 mutant of Arabidopsis thaliana lacks fucosylated xyloglucan because of a lesion in fucosyltransferase AtFUT1

doi:10.1073/pnas.052450699

The mur2 mutant of Arabidopsis thaliana lacks fucosylated xyloglucan because of a lesion in fucosyltransferase AtFUT1

^*Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269; ^‡Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; and ^§Michigan State University–Department of Energy Plant Research Laboratory, East Lansing, MI 48824

Edited by Christopher R. Somerville, Carnegie Institution of Washington, Stanford, CA, and approved January 3, 2002 (received for review August 27, 2001)

Abstract

Cell walls of the Arabidopsis mutant mur2 contain less than 2% of the wild-type amount of fucosylated xyloglucan because of a point mutation in the fucosyltransferase AtFUT1. The mur2 mutation eliminates xyloglucan fucosylation in all major plant organs, indicating that Arabidopsis thaliana fucosyltransferase 1 (AtFUT1) accounts for all of the xyloglucan fucosyltransferase activity in Arabidopsis. Despite this alteration in structure, mur2 plants show a normal growth habit and wall strength. In contrast, Arabidopsis mur1 mutants that are defective in the de novo synthesis of l-fucose exhibit a dwarfed growth habit and decreased wall strength [Reiter, W. D., Chapple, C. & Somerville, C. R. (1993) Science 261, 1032–1035]. Because the mur1 mutation affects several cell wall polysaccharides, whereas the mur2 mutation is specific to xyloglucan, the phenotypes of mur1 plants appear to be caused by structural changes in fucosylated pectic components such as rhamnogalacturonan-II. The normal growth habit and wall strength of mur2 plants casts doubt on hypotheses regarding roles of xyloglucan fucosylation in facilitating xyloglucan–cellulose interactions or in modulating growth regulator activity.

Footnotes

↵ † Present address: National Renewable Energy Laboratory, Golden, CO 80401.
↵ ¶ To whom reprint requests should be addressed at: Department of Molecular and Cell Biology, University of Connecticut, 75 North Eagleville Road, Storrs, CT 06269-3125. E-mail: wdreiter{at}uconnvm.uconn.edu.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

AtFUT1,

Arabidopsis thaliana fucosyltransferase 1;

BAC,

bacterial artificial chromosome;

RG,

rhamnogalacturonans