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

Abstract

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.

Effect of temperature on cucumber mosaic virus satellite-induced lethal tomato necrosis is helper virus strain dependent

“…2) suggest that here at higher temperature the accumulation (and therefore probably the rate of replication) of CARNA 5 had been affected, albeit in opposite directions. With CMV-D significant suppression of necrogenicity was observed in early stages of infection, which correlated with a decrease in D-CARNA 5 titer and corroborated the more detailed analysis of the preceding paper [24]. With CMV-1, however, acceleration of the onset of necrosis correlated clearly with an increase in D-CARNA 5 titer.…”

“…1B, lower panel). For CMV-D this attenuating effect of the higher temperature can also be seen in the disease progression scores of this infection (Table 1) and is in agreement with similar observations in the preceding paper [24]. At least 50% of the plants survived after 24 days and eventually recovered completely.…”

“…In the preceding paper it was shown that raising the temperature during bioassay of tomato necrosis caused by CMV strain D and its necrogenic satellite designated D-CARNA 5 (for c_C_MV-Associated RNA 5) from 24 °C to 32°C prevented the infected tomato seedlings from succumbing to necrosis within 3 weeks [24]. On the other hand, with a different CMV strain/satellite combination a similar temperature increase transforms the relative mild response of the infected tomato plant at 24 °C to a rapid death by necrosis at 28 °C or higher [26].…”

Effect of external and internal factors on the expression of reporter genes driven by theNresistance gene promoter

“…If a temperature-sensitized plant is brought back to a temperature below 28°C after infection, the N gene triggers global HR resulting in the death of the plant. Similar temperature-sensitive responses have been in past reported for cucumber mosaic virus infection of tomato 18 and Arabidopsis infection with Pseudomonas syringae pv tomato DC3000 19 . Although there might be many reasons for temperature sensitivity of plant immune responses, a recent report showed temperature-dependent changes in activity, stability and cellular localization of the SNC1 protein encoded by Arabidopsis NB-LRR type R gene 20 .…”

Mimicry of molecular pretenders: The terminal structures of satellites associated with plant RNA viruses

“…24,25 In addition, factors provided by host plants play crucial roles in the recognition of satRNAs or helper virus genomic RNAs as templates, because different combinations of host plant species, CMV strains, and satRNA strains result in differential effects on the accumulation of satRNAs or CMV RNAs and the symptom severity caused by the combinations. 4,[26][27][28][29][30] satRNAs associated with CMV are single-stranded and linear RNA molecules with varying lengths (ca. 307-405 nt).…”