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.
Prof. Dr. Johannes Wöstemeyer
Tel.: +49 (0)3641 949310/1
Fax: +49 (0)3641 949312