Occurrence of fucosylated and non-fucosylated xyloglucans in the cell walls of monocotyledons: An immunofluorescence study.

The xyloglucans of monocotyledons are known to vary in the abundance of fucosylated side chains, with most commelinid monocotyledons having xyloglucans with lower proportions than non-commelinid monocotyledons. In many commelinid species, and some non-commelinid species that have lower proportions of fucosylated side chains, these side chains have been shown to be cell-type specific. To determine whether it is just the fucosylated side chains that are cell-type specific, or whether xyloglucan is cell-type specific in these species, we used the monoclonal antibody LM15 in conjunction with immmunofluorescence microscopy. We examined the distribution of cell-wall labelling among cell types in these species. The primary walls of all cell types were shown to contain xyloglucans in all species that had cell-type specific distributions of fucosylated side chains. This indicates that it is the fucosylated side chains of xyloglucans that is cell-type specific. Although the functional significance of xyloglucan fucosylation remains unknown, such cell-type specificity supports hypotheses that the fucosylated side chains may indeed have a functional role within the cell wall.