In Apr. 2008, commercially purchased processed potato chips were observed with dark brown arcs and rings typical of corky ringspot disease. This disease is caused by infection with tobacco rattle virus (TRV). A portion of RNA 1 of TRV was amplified by reverse transcription polymerase chain reaction (RT-PCR) from each of eight discolored chips from three different bags purchased at three locations. Sequence analysis of the 463-bp amplicons confirmed that the products were indeed TRV in origin and were 97% identical to TRV sequences of isolates originating in Washington, Florida, and Wisconsin. Extracts from the symptomatic RT-PCR-positive chips were not infectious when mechanically inoculated onto tobacco leaves. To the author's knowledge, this is the first report of the detection of plant virus RNA in a food product after high-temperature frying.
Kathleen Heuss-LaRosa, Rosemarie Hammond, James M. Crosslin, Christine Hazel', and Freddi A. Hammerschlag
In vitro micrografting was tested as a technique for inoculating peach [Prunus persica (L.) Batsch] shoot cultures with Prunus necrotic ringspot virus (PNRSV). Cultured `Suncrest' shoots derived from a naturally infected tree (as indicated by ELISA testing) maintained virus in vitro, with virus concentrations in growing tips and folded leaves being several times those of fully expanded leaves. Infected shoots served as graft bases and source of the virus. Grafted tips were derived from `Suncrest' trees that had tested negative for the virus. Leaf samples were collected from the tips following grafting and analyzed for the presence of virus by slot-blot hybridization with a (DIG)-labeled cRNA probe derived from PNRSV RNA 3. Rates of successful grafting ranged from 55% to 73% in three trials and PNRSV was found in all tips analyzed. Virus concentrations approximated those found in source shoots, suggesting that in vitro micrografting should be useful for screening transformed peach shoots for coat protein-mediated resistance to PNRSV. Chemical name used: digoxigenin (DIG).