Actin Rearrangements in Pollen Tubes are Stimulated by the Self-Incompatibility (SI) Response in Papaver Rhoeas L.

Abstract

Self-incompatibility (SI) is a genetically-controlled system used by many flowering plants to prevent self-fertilization. We have been investigating SI in Papaver rhoeas for a number of years, and have begun to build up a picture of some of the signalling events and mechanisms involved in this specific inhibition of pollen tube growth. Pollen tubes elongate by tip growth, which is dependent upon the actin cytoskeleton, the structure of which is controlled by actin-binding proteins. To date, no studies, to our knowledge, have investigated the effect that a self-incompatible response may have on actin organisation in pollen tubes. Our investigations provide clear evidence that the actin cytoskeleton of incompatible pollen tubes undergoing SI is dramatically altered. These data strongly suggest that the actin cytoskeleton is targetted by the signalling pathway stimulated in the SI response. These findings may have implications for our understanding of regulation of pollen tube growth.