Sporophyte-gametophyte interactions in the pollen-pistil system. 1. Cell wall lectins

Location, time-course of accumulation, and carbohydrate specificity of lectins 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 pistil 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 hours after compatible pollination, lectin activity increased and their carbohydrate specificity changed. The highest lectin activity was recorded in sporophytic stylar tissues, the site of pollen recognition, which determines further growth (compatible pollination) or abortion (incompatible pollination) of pollen tubes. Lectins are presumed to participate in pollen-pistil cell interactions.