Changes in Lectin Activity in Plants Treated with Resistance Inducers

We studied the changes in lectin activity in tobacco leaf discs and potato tubers treated with polysaccharides (chitosan, glucomannan, and dextran sulfate), enzymes (cellulase and pectinase), or monosaccharides (glucose and glucosamine). All these substances changed lectin activity to a certain extent (significantly or as a tendency). The content of membrane lectins in the chloroplasts (tobacco leaf discs) usually decreased considerably immediately after the treatment (1–2 days) but increased later (2–4 days). Generally, a higher lectin activity was characteristic of potato tubers treated with the inducers. The enzymes increased lectin activity during the whole observation period (5 days). A pronounced antiviral activity was observed in the hypersensitive tobacco–tobacco mosaic virus system only after treatment with chitosan and glucomannan.