CA2-HYBRIDA HORT. DURING GROWTH OF THE POLLEN-TUBE - CYTOCHEMICAL ANDRADIOGRAPHIC STUDIES( IN THE PISTIL OF PETUNIA)

The aim of the present study was to find the source of postpollination increase in calcium content in the transmitting tract in the style of Petunia hybrida Hort. Cytochemical and radiographic studies revealed a progressive increase in the level of free and loosely bound calcium ions in the course of successive developmental stages of the pollen tu bes in the pistil. A surprising phenomenon was the increase in Ca2+ co ntent in the extracellular regions of the transmitting tract preceding the penetration of the pollen tubes therein. We suggest that the main sources of postpollination increase in calcium in the pistil are the walls of the transmitting cells and the intercellular matrix and, prob ably, additional Ca2+ uptake, initiated by pollination.