Ultrastructural Observations on the Dikaryotic Haustorium ofCronartium Flaccidum(Alb. & Schw.) Wint. inVincetoxicum HirundinariaMedicus

Abstract

SUMMARYThe haustorium of the uredial stage of Cronartium flaccidum in Vincetoxicum hirundinaria was studied with TEM. The observations concern the haustorial mother cell and its relation to the host cell wall, the penetration peg, the shape and the cytoplasm of the haustorium and some host cell organelles in relation to the haustorium. The presence of collars was noted. These features are similar to those described for host-dikaryotic haustorium relationship in other rusts. The extrahaustorial matrix however shows a unusual development. In fact, it wraps the whole length of haustorial neck although it is separated from the haustorial neck wall by the extrahaustorial membrane doubled in this region. The probable significance of this host-parasite interface, perhaps limited to the genus Cronartium, is discussed.