Location, time-course of accumulation, and carbohydrate specificity of lect
ins were studied in the male gametophyte and sporophytic pistil tissues of
Petunia hybrida L. and Allium cepa L., using the method of hemagglutination
of trypsinized rabbit erythrocytes. Prior to pollination, sporophytic pist
il tissues manifested higher hemagglutinating activity and a higher content
of cell-wall lectins than the pollen; besides, the two organs differed in
their profiles of lectin carbohydrate specificity. During the first two hou
rs after compatible pollination, lectin activity increased and their carboh
ydrate specificity changed. The highest lectin activity was recorded in spo
rophytic stylar tissues, the site of pollen recognition, which determines f
urther growth (compatible pollination) or abortion (incompatible pollinatio
n) of pollen tubes. Lectins are presumed to participate in pollen-pistil ce
ll interactions.