Indirect immunofluorescence detection of the arabinan (LM6) epitope in transverse sections of fern petioles and lycophyte stems. Calcofluor White fluorescence (a, d, g, k, m, n, p, q, u) shows the full extent of cell walls. (a–c) Detection of the LM6-epitope in parenchymatous cell types of vascular bundles of Todea sp.
(a–c) and Blechnum brasiliense
(d–f). (g–m) Similar distribution pattern of the LM6-epitope is found in the vascular bundle (g–j) of Asplenium theciferum. Higher magnification (k–m) showing binding of LM6 to the cell walls of phloem parenchyma (pp), xylem parenchyma (xp) and pericycle (p). (n–p) LM6 binding to epidermal (e) cell walls, including the guard cell walls (gc) of stomata. (q–t) Detection of LM6 epitope in cortical parenchyma after pectate lyase (PL) treatment (s). (u–x) LM6-epitope is not detected in the lycophyte Huperzia squarrosum, even after pectate lyase treatment (w). Abbreviations: p, pericycle; phl, phloem; xp, xylem parenchyma; pp, phloem parenchyma; par, parenchyma; coll, collenchymatous tissue; e, epidermis. No primary antibody controls are provided (c, f, j, t, x). Scale bars: 40 μm.