CORESTA Meeting, Agronomy/Phytopathology, Montreux,1997, AP62

In vitro germination of Orobanche seeds in presence of tobacco root exudates and plant growth regulators

Institute of Genetic Engineering, Kostinbrod, Bulgaria.
Broomrape ( Orobanche ramosa L.) is an obligate root parasite which causes severe reduction of tobacco quality and yield. Seeds of the parasite germinate only in the presence of the host plant. An in vitro system for seed germination was established in order to give more insight of plant-parasite interactions. Tobacco root exudates released from intact tobacco roots originated from three different tobacco cultivars had a positive effect on germination of Orobanche seeds. Plant growth regulators as: GA3, IAA and kinetin stimulated germination and calli formation of broomrape seeds from 20 to 91% depending on their concentration in the medium. Different type of calli with many root-like protrusions were formed. The histological examination the place of the contact between calli of broomrape and host roots in vitro proved that there is penetration of the parasite calli into tobacco root. This system can be used for studying the biochemistry of host-parasite interactions and also the stimulatory effect of the compounds of root exudates.