Transfer of genes from the mycoparasite Parasitella parasitica to its hosts

The infection of the zygomycete Absidia glauca and various other Mucor-like hosts by the facultative mycoparasite Parasitella parasitica is accompanied by the formation of a limited cytoplasmic continuum between the partners. Nuclei of the parasite invade the host's mycelium. We could show by simple genetic experiments that many different auxotrophic mutants of Absidia glauca are complemented by acquiring Parasitella's genetic material. We also showed at the molecular level that an artificial plasmid coding fore neomycin resistance is efficiently transferred. In any case gene transfer depends on formation of the typical infection structures.

At least for the host Absidia glauca successful infection requires that the partners belong to complementary mating types. This observation points towards a physiological relationship between parasitism and the sexual pathway. In Mucoraceae sexual differentiation depends on the synthesis of the sex hormone trisporic acid. In Absidia glauca trisporic acid is synthesized via the complementary action of both mating types. Also complementary combinations of Absidia glauca and Parasitella parasitica produce trisporic acid. Therefore we hypothesize that trisporic acid is also involved in host / parasite recognition.

Presently, this parasexual system is studied under two different but complementary aspects. Anke Burmester studies the expression of one of the genes involved in trisporic acid biosynthesis, the gene for 4-dihydro-methyltrisporic acid dehydrogenase. The second aspect covers the evolutionary aspects of this system. By analyzing gene transfer (auxotrophy-complementing markers; plasmid transfer; transfer of species specific repetitive DNA) under near-natural conditions in soil, we ask for the importance of this system for gene flow in zygomycetes.

Contact

Prof. Dr. Johannes Wöstemeyer
Tel.: +49 (0)3641 949310/1
Fax: +49 (0)3641 949312
e-mail: b5wojo@rz.uni-jena.de