VIRUS-INFECTIONS IN 3 MARINE BROWN-ALGAE - FELDMANNIA-IRREGULARIS, F-SIMPLEX, AND ECTOCARPUS-SILICULOSUS

Culture studies with healthy and virus-infected isolates of Ectocarpus siliculosus, Feldmannia simplex and F. irregularis gave the following results: Virus particles are produced in deformed reproductive organs (sporangia or gametangia) of the hosts and are released into the surr ounding seawater. Their infective potential is lost after several days of storage under laboratory conditions. New infections occur when gam etes or spores of the host get in contact with virus particles. The vi rus genome enters all cells of the developing new plant via mitosis. V irus expression is variable, and in many cases the viability of the ho st is not impaired. Infected host plants may be partly fertile and pas s the infection to their daughter plants. Meiosis of the host can elim inate the virus genome and generate healthy progeny. The genome of the Ectocarpus virus consists of dsDNA. Meiotic segregation patterns sugg est an intimate association between virus genome and host chromosomes. An extra-generic host range has been demonstrated for the Ectocarpus virus. Field observations suggest that virus infections in ectocarpale an algae occur on all coasts of the world, and many or all Ectocarpus and Feldmannia populations are subject to contact with virus genomes.