Location of (1 → 3)- and (1 → 3),(1 → 4)-β-D-glucans in vegetative cell walls of barley (Hordeum vulgare) using immunogold labelling.

•  (1 → 3),(1 → 4)-β-Glucans occur only in the cell walls of the family Poaceae (grasses and cereals) and related families, but little is known about their distribution among walls of different cell types or within walls. •  The locations of (1 → 3)- and (1 → 3),(1 → 4)-β-glucans in the walls of the coleoptile, first leaf and root tip of barley (Hordeum vulgare) seedlings were determined using immunogold labelling. •  All the walls were labelled with the (1 → 3),(1 → 4)-β-glucan antibody, except those of the outer root cap cells. Labelling of the primary walls was heavy in the coleoptile and leaf, but light or very light in the root tip. Two types of primary wall labelling occurred: in the coleoptiles (except the walls of the epidermis and two layers of parenchyma under this) and in the leaf, labelling was throughout the walls; in the root tips, labelling was only adjacent to the plasma membrane. Small amounts of labelling occurred with the (1 → 3)-β-glucan antibody, mostly over plasmodesmata. Both antibodies labelled cell plates. •  (1 → 3),(1 → 4)-β-Glucans occur widely in the cell walls of vegetative organs of the barley seedlings, including the walls of meristematic tissues.