ULTRASTRUCTURAL STUDIES OF BINDING OF CONCANAVALIN-A TO PLASMALEMMA OF HIGHER PLANT PROTOPLASTS

The binding of Concanavalin A to the plasmalemma of higher plants was studied using protoplasts of 2 species. The lectin aggregates both tobacco (Nicotiana tabacum L.) leaf protoplasts and protoplasts prepared from a suspension cell culture of grapevine (Vitis vinifera L.). Differences in lectin binding were investigated using Concanavalin A conjugated to ferritin or bound to colloidal gold. Tobacco protoplasts exhibit continuous and saturated labeling of the plasmalemma surface with gold-Concanavalin A mixtures. Vine protoplasts under the same conditions show a discontinuous and patchy distribution of label. These results are discussed in terms of a possible binding mechanism.