Studies on peach mosaic virus
Peach mosaic virus (EPPO A1 quarantine pest as peach American mosaic closterovirus) has been studied by two different teams of researchers in US and Canada. ;It can be recalled that peach mosaic was first found in 1931 in Texas and Colorado (US), then in other states and in Mexico. However, its spread and incidence were limited by quarantine programmes in the USA (see EPPO RS 97/194). This disease affects several Prunus species and is spread by the peach bud mite Eriophyes insidiosus. The virus associated with this disease has been found to be serologically related to cherry mottle leaf closterovirus.
Gispert et al. (1998) have purified the virus (from symptomatic leaves of Chenopodium amaranticolor mechanically inoculated with the virus) which is consistently found with peach mosaic disease. The particles observed by electron microscopy are long, flexuous filamentous rods with an average length of 888 nm. They have also studied physio-chemical properties of the virus (capsid protein size of 27 kD, genomic RNA 8.1 kb, etc.) and found that it has similarities with closteroviruses, capilloviruses and trichoviruses, but felt that it appears to be most closely related to trichoviruses (James ; Howell had previously suggested a closterovirus). Polyclonal antibody produced against the purified virus, reacted with samples from peach mosaic and cherry mottle leaf infected plants.
James ; Howell (1998) have also purified a filamentous virus (752 nm long, 9.25 nm wide, with striations of 3.47 nm in pitch, coat protein subunit 20.5 kD) from C. quinoa (mechanically inoculated from diseased peach). The herbaceous host range of peach mosaic virus includes C. amaranticolor, C. quinoa and Nicotiana occidentalis. The virus could successfully be bud-transmitted from infected peach to peach indicator plants (P. persica cv. Elberta) which showed typical symptoms. Transmission to P. avium cv. Bing and P. mahaleb was unsuccessful. In serological assays, peach mosaic virus polyclonal antibody gave a cross-reaction with cherry mottle leaf closterovirus; and monoclonal and polyclonal antibodies for cherry mottle leaf closterovirus cross-reacted with all tested isolates of peach mosaic virus. The authors felt that the virus isolated is probably the causal agent of peach mosaic disease. In addition, it is stated again that peach mosaic virus is clearly different from peach latent mosaic viroid (quarantine status under review).
Sources
Gispert, C.; Perring, T.M.; Creamer, R. (1998) Purification and characterization of peach mosaic virus.
Plant Disease, 82(8), 905-908.
James, D.; Howell, W.E. (1998) Isolation and partial characterization of a filamentous virus associated with peach mosaic disease.
Plant Disease, 82(8), 909-913