Cucumber Mosaic Virus Associated RNA 5: Causal Agent for Tomato Necrosis

Abstract

A small replicating RNA, encapsidated with and dependent on, but not part of the viral genome, modifies disease expression depending on the host. In tomato plants, it causes a lethal necrotic disease which is probably the same as that which, in 1972, destroyed most of the field tomato crop in large regions of the French Alsace.

Cucumber Mosaic Virus D Satellite RNA-Induced Programmed Cell Death in Tomato

“…Tomato plants infected with CMV and D-satRNA were characterized by necrosis throughout the plants at the late stage of infection (Kaper and Waterworth, 1977). The extent of necrosis in the plants was influenced by environmental factors, such as temperature, and infected plants at a particular developmental stage were more susceptible to cell death (Kaper et al, 1995).…”

“…D-satRNA (335 nucleotides long) induces a lethal systemic necrosis in tomato that has been reported as epidemic in France, Italy, and Spain (Kaper and Waterworth, 1977;Jordá et al, 1992). The molecular and cellular mechanisms of the disease, which can cause a catastrophic reduction in tomato production, remain unknown, although the sequences in D-satRNA responsible for the lethal necrosis have been determined (Sleat and Palukaitis, 1990;Sleat et al, 1994).…”

“…The conspicuous symptom of tomato plants infected by D-satRNA and CMV is cell death, the cause of the lethal systemic necrosis (Kaper and Waterworth, 1977). In recent years, plant cell death has been studied extensively (Dangl et al, 1996;Jones and Dangl, 1996;Greenberg, 1997;Pennell and Lamb, 1997).…”

“…For some specific CMV and satRNA combinations, RNA 2 of CMV has been shown to be involved in determining pathogenicity (Sleat et al, 1994). Recently, however, the minus-strand D-satRNA expressed from a potato virus X vector was shown to induce similar necrosis in tomato, thereby excluding the specific role of CMV in the pathogenicity of D-satRNA, except for its function as a helper virus in the host plants (Taliansky et al, 1998).The conspicuous symptom of tomato plants infected by D-satRNA and CMV is cell death, the cause of the lethal systemic necrosis (Kaper and Waterworth, 1977). In recent years, plant cell death has been studied extensively (Dangl et al, 1996;Jones and Dangl, 1996;Greenberg, 1997;Pennell and Lamb, 1997).…”

Replication of cucumber mosaic virus satellite RNA in vitro by an RNA‐dependent RNA polymerase from virus‐infected tobacco

“…In addition CMV encapsidates a satellite RNA with the designation CARNA 5 (CMV-associated RNA 5), which comprises a group of sequencerelated variants 334-386 nucleotides (nt) long [2,3]. Although CARNA 5 is essentially sequence-unrelated to the CMV genome, it depends on the farter's presence for replication [4,5]. Because CARNA 5 can modify virgl disease symptoms in widely varying ways, from inducing plant death at one extreme to complete amelioration of symptoms at the other (reviewed in [6,7]), and due to its usefulness in practical agriculture [8,9], this satellite has become by far the one most intensively studied among several now characterized [I0].…”