PRESUMED PHYLOGENETIC BASIS OF THE CORRELATION OF PECTIN DEPOSITION PATTERN IN POLLEN-TUBE WALLS AND THE STYLAR STRUCTURE OF ANGIOSPERMS

Using monoclonal antibody (MAb) JIM5 as an immunofluorescent marker fo r polygalacturonic acid (pectin), we examined the pectin deposition pa ttern in the walls of in vitro grown pollen tubes of 30 species belong ing to 18 families and in vivo grown pollen tubes of Lilium longifloru m (hollow style) and Petunia hybrida (solid style). Based on the plant evolutionary scheme, it seems that primitive species have a hollow st yle and a moderately uniform pectin sheath in the pollen tube wall, wh ereas advanced species have a solid style and periodic ring-like struc tures in the pectin layer of the tube wall. This might suggest evoluti onary adaptation of the pollen tube wall to the increasing physical re sistance encountered in the style.