Identification of two functional xyloglucan galactosyltransferase homologs and in brassicaceous vegetables.

Xyloglucan (XyG) is the predominant hemicellulose in the primary cell walls of most dicotyledonous plants. Current models of these walls predict that XyG interacts with cellulose microfibrils to provide the wall with the rigidity and strength necessary to maintain cell integrity. Remodeling of this network is required to allow cell elongation and plant growth. In this study, homologs of (), which encodes a XyG-specific galactosyltransferase, were obtained from () to (. Genetic complementation showed that and rescue the phenotypic defects of the mutant. Xyloglucan subunit composition analysis provided evidence that and encode a galactosyltransferase, which transfers a galactose residue onto XyG chains. The detection of XXFG and XLFG XyG subunits (restoration of fucosylated side chains) in mutants overexpressing or show that MUR3 from to are comparable as they add Gal to the third xylosyl residue of the XXXG subunit. Our results provide additional information for functional dissection and evolutionary analysis of genes derived from brassicaceous species.