Tomato White Leaf: The Relation of an Apparent Satellite RNA and Cucumber Mosaic Virus

Abstract

In 1970, an apparently new disease of tomato (L. esculentum) was oberved near Geneva, New York [USA]. 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 RNA 1 + 2, 3, 4, 4a, and 5 in order of decreasing sedimentation velocities, respectively. While only RNA 1 + 2 + 3 were required for infectivity, tomatoes inoculated with these RNA 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 RNA 1 + 2 + 3 + 5. Inoculum that contained CMV-WL RNA 5 and RNA 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 RNA 1 + 2 + 3, but were symptomless when inoculated with CMV-WL RNA 1 + 2 + 3 + 5.