A relationship between callose and ectodesmata in epidermal cells of Allium cepa L.

The outer wall of adaxial epidermal cells of onion bulb scales shows punctate callose deposits. The abundance of these callose deposits is highly variable, and seems to correlate with the distribution of ectodesmata. It is proposed that callose is involved in the regulation of ectodesmata as a waterflow regulator and/or molecular filter, thus influencing the cell-environment interaction.