Self-incompatibility and the pollen-stigma interaction inTradescantia ohiensis rafin

Abstract

Self-incompatibility (SI) is reported for an accession ofTradescantia ohiensis. Pollen tube inhibition is stigmatic. The stigma is wet and papillate, the papillr surface bearing conspicuous blebs particularly in the mid- and basal regions of the cell. A proteinaceous pellicle is present on the surface of the papillar cuticle. The penetration of the stains calcofluor white and alcian blue into the cell wall of fresh stigma papillae strongly indicates that the permeability of the papillae is greatest at the mid-region of the cell and not at the tip. When single pollen grains are attached to the tip of a papilla there is either no response at all or the pollen adheres to the papilla. When attached in the mid-region pollen adheres, and often germinates. It is concluded that the sites of pollen receptivity are the mid- and basal regions of the papular cell.