Abstract

The filamentous marine brown algae Ectocarpus siliculosus and E. fasciculatus are frequently infected by DNA viruses. We used polymerase chain reaction amplification (PCR) of a virus-specific nucleotide sequence 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 isolates contained viral DNA. Among these were four sporophytes, which produced gametophytes free of virus DNA. This observation supports previous studies showing that the viral genome segregates like a Mendelian trait during meiosis. The pandemy and epidemiology of the host-virus relationship in Ectocarpus is discussed.