Studien an Cuscuta reflexa Roxb.: III. Zur Frage einer cytokininabhängigen Nährstoffaufnahme )

Abstract

Summary The content of cytokinin-active substances was shown to be lower in haustoria bearing sections of the parasite Cuscuta reflexa than in the tissue of the attacked axes of the host Vicia faba. The transport of radioactive sugars from the host axis to its roots is drastically decreased by the parasite, and removal of the Toot is without influence on the sugar uptake of Cuscuta. From these observations the mechanism of uptake into the root and Cuscuta is suggested to be different. Pretreating a host leaf with kinetin did not decrease the transport of [U-14C]-sucrose to the parasite. When kinetin was applied to Cuscuta axis it maintained the green colour at the site of application, inhibited stem lengthening, and increased stem thickening. Papillae similar to the early stages of haustoriae were formed. The reason for the strong parasitic deprivation of nutrients is regarded as the action of enzymes mediating a direct connexion of the parasite to the phloem of the host, and consequently, a rapid uptake of the nutrients. A hormone-induced “attraction power” seems not to be the mechanism involved in the host-parasite relations.