CHANGES OF ELECTRIC-POTENTIAL IN PISTILS OF PETUNIA-HYBRIDA HORT. ANDBRASSICA-NAPUS L. DURING POLLINATION

The pattern of electric signals accompanying compatible and incompatib le pollination were studied in pistils of petunia (Petunia hybrida L.) and rape (Brassica napus L). Electric potential was recorded for 4-7 hours with non-polarizable Ag/AgCl electrodes implanted into the ovary and beneath the sigma. At the end of measurements, pistils were fixed and the growth of pollen tubes was analyzed under a fluorescent micro scope. Action potentials appeared in both species. In rape the potenti al dropped by 10 mV for few minutes after pollination regardless of th e compatibility of the cross. In this species, during compatible polli nation action potentials with amplitudes of 15-20 mV were recorded up to one hour after pollination. They were followed by a long lasting de crease of the potential by 10 to 50 mV. Contrary, after the self-incom patible pollination, action potentials were rare and of lower amplitud es and the potential gradually raised in comparison to the initial lev el. During the first hour after the compatible pollination of Petunia hybrida series of action potentials with amplitudes reaching 10-20 mV were recorded. Al the time corresponding to the pollen tubes entrance to the transmitting tissue of the style, action potentials reaching up to 40 mV were followed by a steady decrease of the potential. The ele ctric signals traveled along the style with velocity of 25 mm/s. Incom patible pollination in petunia resulted only in minor oscillation and gradual increase of the potential up to 100 mV in comparison to the in itial level. The present investigation demonstrated that each phase of pollen-stigma recognition events, germination and growth of pollen tu bes within the style have its characteristic pattern of electric chang es which was species specific and depended on compatibility of the cro ss.