Fig. 3

Relative S-adenosyl l-methionine (AdoMet) content and the degree of GX methylation in fpgs1 and wild-type plants. a SAM content in wild-type (WT) and fpgs1 stem tissue samples analyzed according to the method of Castro et al. [37]; a twofold reduction in AdoMet was observed in the fpgs1-1 compared to WT plants. Five biological replicates were used during the measurement. b Determination of the degree of GlcA O-methylation of 4-O-methyl glucuronoxylan (GX) isolated from fpgs1-1 and wild-type stem cell walls. Xylo-oligosaccharides were generated by endoxylanase treatment of the 1 N KOH-soluble GXs and analyzed using 600-MHz 1H NMR spectroscopy. The H-1 and H-5 resonances of α-D-GlcpA residues are labeled U1 and U5, respectively. The M1 and M5 labels correspond to H-1 and H-5 of 4-O-methyl α-D-GlcpA. Resonances assigned as H-1 of α-D-GalpA, α-L-Rhap, and β-D-Xylp linked to Rha residues are labeled G, R and X, respectively. The degree of GlcA methylation was determined by integration of U1 and M1 in the 1-D spectra (dotted box). c The NMR analyses of GX oligosaccharides were generated by two independent endoxylanase treatments showed a 10 % reduction of the degree of GlcA O-methylation of fpgs1-1 GX compared with wild-type GX