DETECTION OF VIRUS-DNA IN ECTOCARPUS-SILICULOSUS AND E-FASCICULATUS (PHAEOPHYCEAE) FROM VARIOUS GEOGRAPHIC AREAS

The filamentous marine brown algae Ectocarpus siliculosus and E. fasci culatus are frequently infected by DNA viruses. We used polymerase cha in reaction amplification (PCR) of a virus-specific nucleotide sequenc e to detect the presence of viral DNA in extracts of Ectocarpus plants , and applied this technique to a collection of 97 unialgal Ectocarpus cultures from coasts of all oceans and continents. We found that 42 i solates contained viral DNA. Among these were four sporophytes, which produced gametophytes free of virus DNA. This observation supports pre vious studies showing that the viral genome segregates like a Mendelia n trait during meiosis. The pandemy and epidemiology of the host-virus relationship in Ectocarpus is discussed.