Studies on poplar mosaic virus and its relation to the host

An extended survey of poplar species and cultivars yielded data on susceptibility to poplar mosaic virus (PMV). Three symptom types were distinguished: two different leaf variegations and a necrosis on veins and leaf-stalks. This venal and petiolar necrosis and a diffuse leaf spotting caused considerable losses to clones of Populus deltoides angulata. Careful observations did not yield evidence for any relation between symptoms on a leaf and those on the shoot grown from its axillary bud the following season. As well as observations, results of inoculation tests on the local lesion host Vigna unguiculata with extracts from young sprouts grown from one-bud cuttings suggested an uneven distribution of PMV in diseased cuttings. A number of herbaccous hosts were found to be susceptible to PMV. Systematically infected leaves of N. glutinosa and N. debney proved suitable sources for further purification of the virus. The examination of highly purified virus preparations revealed a sedimentation coefficient of 165 S. By repeated immunization of rabbits with the virus, antisera were obtained with a titre of 1/2048. Investigations on the serological relationship between PMV and other viruses of about the same size and shape revealed that PMV belonged neither to the potato virus S group nor to the potato virus Y group.