Mild temperature "stress" and callose synthesis.

Seedlings of Zea mays L., Sorghum vulgare, Pisum sativum L., Phaseolus aureus, Glycine max L. and Lycopersicum esculentum were grown at 20°C and at 26°C. The seedlings were fixed in glutaraldehyde and sections were examined for aniline-blue-induced fluorescence, which is supposedly indicative of β-1,3-glucans or callose. There was much more aniline-blue fluorescence in Zea, Glycine and Phaseolus seedlings grown at 20°C compared with 26°C whereas Pisum and Lycopersicum seedlings grown at 26°C showed more fluorescence than those grown at 20°C. In Zea, large deposits of fluorescent material were particularly noticeable in the walls of elongating cells around the shoot apex and in root-cap cells, and appeared to be closely associated with a few of the pitfields. The remaining pitfields showed the normal, low level of aniline-blue fluorescence.