Virus-like particles associated with dieback symptoms in the brown alga Ecklonia radiata

Since 1991 epidemic dieback of the kelp Ecklonia radiata has been observed at the Leigh h4arine Reserve and other sites in northern New Zealand. As the dominant phaeophycean E. radiata is a very important component of the eastern coastal ecosystem, providing both food and refuge for many species. Examination of the E. radiata sap extracts by electron microscopy detected the presence of both straight (ca 280 nm) and flexuous (ca 700 to 900 nm) virus-like filamentous particles. Extracts from several dieback-affected plants also reacted positively with potyvirus group monoclonal antibody.