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Etiology

Tomato White Leaf: The Relation of an Apparent Satellite RNA and Cucumber Mosaic Virus. D. Gonsalves, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; R. Provvidenti(2), and M. C. Edwards(3). (2)(3)Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456. Phytopathology 72:1533-1538. Accepted for publication 23 April 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1533.

In 1970, an apparently new disease of tomato (Lycopersicon esculentum) was observed near Geneva, New York. Affected plants had a striking whitish green mottle on the leaf laminae, whereas petioles and stems were greenish white instead of the normal purplish green. Immature fruit were almost white, but eventually developed normal red color at maturity. Although affected plants were small, the disease was not lethal. Cucumber mosaic virus, designated CMV-WL, was consistently recovered from symptomatic plants. In sucrose density gradients, RNA extracted from CMV-WL sedimented as five components designated as RNAs 1+2, 3, 4, 4a, and 5 in order of decreasing sedimentation velocities, respectively. While only RNAs 1+2+3 were required for infectivity, tomatoes inoculated with these RNAs did not develop white leaf symptoms, but developed a downward leaf curling along the midvein and greatly reduced leaf lamina. However, white leaf symptoms developed on tomatoes inoculated with CMV-WL RNAs 1+2+3+5. Inoculum that contained CMV-WL RNA 5 and RNAs 1+2+3 of the CMV-C strain also produced white leaf on tomato, but symptoms were milder. Nicotiana tabacum ‘Havana 423’ often developed a brilliant chlorosis when inoculated with CMV-WL RNAs 1+2+3, but were symptomless when inoculated with CMV-WL RNAs 1+2+3+5.