vealed a typical “patchy” pattern of callose accumulation, identical to the one observed by Radford et al.
(1998), along the transverse and longitudinal walls of
epidermal and cortical cell layers, suggesting their
preferential localization to PD regions (Fig. 2, D–F).
This patchy pattern of callose was ostensible especially in sections where the cell wall and membraneous regions in the cytoplasmic areas were preserved
(paradermal sections). The specificity of dye binding
to callose enriched PD/pit field regions was confirmed by the accurate detection of naturally occurring callose from the sieve tube elements of control
root PD (Fig. 2C).