Infection of Cultivated Gesneriads by Two Strains of Tobacco Mosaic Virus. F. W. Zettler, Professor, Plant Pathology Department, University of Florida, Gainesville 32611. J. Nagel, Graduate Student, Plant Pathology Department, University of Florida, Gainesville 32611. Plant Dis. 67:1123-1125. Accepted for publication 18 April 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1123.

The U₁ and U₂ strains of tobacco mosaic virus (TMV) were implicated as being widespread in cultivated gesneriads (family Gesneriaceae: Achimenes, Aeschynanthus, Chirita, Codonanthe, Episcia, Gloxinia, Kohleria, Nematanthus, Streptocarpus, Smithiantha, and Sinningia spp.). Infected plants were found in all six collections surveyed but not in 73 herbarium specimens representing plants collected from their native habitats in 16 South and Central American countries. Foliage symptoms of most infected plants were inconspicuous. Based on serological results, the U₂ strain was much more common than the U₁ strain (83 and 17% of 133 infected plants, respectively). In addition to the rigid rod-shaped TMV particles, flexuous rods with a modal length of 486 nm were seen in negatively stained leaf extracts of Smithiantha but not in any of the other gesneriads examined.

Keyword(s): × Achimenantha, × Codonatanthus, × Coltrichantha.