THE REPLICATION OF A NECROGENIC CUCUMBER MOSAIC-VIRUS SATELLITE IS TEMPERATURE-SENSITIVE IN TOMATO

Lethal necrosis development in tomato plants infected with cucumber mosaic virus (CMV) strain D containing the necrogenic satellite D-CARNA 5 and held at 32 degrees C is shown to be impaired. CARNA 5 accumulation in tomato at 32 degrees C is reduced about 100-fold compared to accumulation in plants held at 24 degrees C, while viral RNA accumulation is reduced about 5-fold. CMV-infected tomato held for 3 days at 24 degrees C prior to shift to 32 degrees C do not develop lethal necrosis. Longer incubations at 24 degrees C prior to shift to 32 degrees C allow necrosis to develop. CMV-infected plants held for up to 4 weeks at 32 degrees C required an additional 8-10 days at 24 degrees C to develop necrosis. Necrogenic CMV-infected plants held at 24 degrees C and analyzed 3 days p.i. contained detectable amounts of ss- and ds-CARNA 5; upon shift to 32 degrees C, such CARNA 5 declined to undetectable levels and lethal necrosis did not occur. There appear to be temperature-sensitive factors that are required for efficient satellite replication which are not required for efficient viral RNA replication. Whether these factor(s) are of host or satellite origin is uncertain.