Viruslike particles in the brown alga Ectocarpus

Mature plants of Ectocarpus fasciculatus were sectioned and the plurilocular sporangia of some plants were found to contain polyhedral viruslike particles. The particles are ca. 170 nm in diameter, possessing both a shell and core, and are confined to the nuclear regions of the developing spores. A possible cylindrical form of this presumed virus is found in some nuclei. The “infection” could be systemic within the plant, and lysis of the zoospores occurs if large numbers of the viruslike particles are present.