The replication of a necrogenic cucumber mosaic virus satellite is temperature-sensitive in tomato

Summary 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 °C is shown to be impaired. CARNA 5 accumulation in tomato at 32 °C is reduced about 100-fold compared to accumulation in plants held at 24 °C, while viral RNA accumulation is reduced about 5-fold. CMV-infected tomato held for 3 days at 24 °C prior to shift to 32 °C do not develop lethal necrosis. Longer incubations at 24 °C prior to shift to 32 °C allow necrosis to develop. CMV-infected plants held for up to 4 weeks at 32 °C required an additional 8–10 days at 24 °C to develop necrosis. Necrogenic CMV-infected plants held at 24 °C and analyzed 3 days p.i. contained detectable amounts of ss- and ds-CARNA 5; upon shift to 32 °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.