A common group I intron between a plant parasitic fungus and its host.

The self-splicing RNAs known as group I introns exist in many organisms, but their distribution is difficult to explain. We hypothesize that group I introns have been transferred between a parasite and its host. We describe here the discovery of a common group I intron sequence between a plant-parasitic fungus, Protomyces inouyei, and its host, Youngia japonica. It strongly supports our theory that the group I intron had been transferred from the host plant to the parasitic fungus in the course of evolution.