Peter E. Thomas

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Fifty-nine potato cultivars or breeding clones were planted near Umatilla, OR and/or Pasco, WA, in fields known to be infested with tobacco rattle virus (TRV) and vector nematodes,Paratrichodorus allius Jen. (Sid.). Tubers from these field plots were cut and examined for corky ringspot (CRS) symptoms. Reverse transcription-polymerase chain reaction (RT-PCR)(More)
A search was conducted to detect evidence for interactions between potato leafroll virus (PLRV)-derived transgenes expressed in Russet Burbank potato and viruses to which the transgenic plants were exposed and by which they were infected. More than 25000 plants in 442 lines transformed with 16 different coat protein gene (CP) constructs and nearly 40000(More)
Potato leafroll poleovirus and the Colorado potato beetle (Leptinotarsa decemlineata (Say)) are major pests of potato in the USA. The US Department of Agriculture estimates that over 50% of annual insecticide use on potato is applied to control the Colorado potato beetle and aphids that transmit potato leafroll virus (PLRV). To address this issue, Russet(More)
Potato germplasm was assessed for resistance to corky ringspot disease (CRS) incited by transmission of tobacco rattle virus (TRV). TRV is transmitted by the stubby root nematode,Paratrichodorus allius, in the Pacific Northwest, and characterized by necrotic areas in the tuber. Four tests were conducted at two different problem fields in Umatilla, OR and(More)
Tobacco rattle virus (TRV)-specific products were obtained by reverse transcription-polymerase chain reaction (RT-PCR) of nucleic acid extracts prepared from tubers exhibiting symptoms of corky ringspot (CRS) disease. Viral origin of amplification products was confirmed by hybridization of PCR products with a nonradioactively-labeled complementary DNA probe(More)
Soil samples from corky ringspot (CRS) problem fields of potato in the states of Washington and Oregon were collected and planted withNicotiana tabacum ‘Samsun NN’ tobacco to bait tobacco rattle virus (TRV) and to increaseParatrichodorus allius populations, the vector of TRV. Pathogenicity of three isolates of TRV was assessed on Russet Burbank and Russet(More)
Resistance to potato leafroll virus (PLRV) was detected in an accession of Solanum chacoense. Inoculations with viruliferous aphids and subsequent graft challenges using Datura tatula and potato as PLRV sources determined that resistance appears to be of an extreme type. Virus was not detectable using enzyme-linked immunosorbent assay (ELISA) in S.(More)
The ability of several weed species to serve as hosts for tobacco rattle virus (TKV), the causal agent of corky ringspot disease of potato (CRS), and its nematode vector,Paratrichodorus allius, was investigated in greenhouse studies. ViruliferousP. allius multiplied on 24 out of 37 weed species tested, indicating they were suitable hosts of the vector.(More)
The reliability of the standard double antibody sandwich enzymelinked immunosorbent assay (DAS-ELISA) was compared with a shorter, two-step DAS procedure in which sample and conjugate were mixed and incubated together in one step. The two assays were compared using beet western yellows virus and potato leafroll, M, S, X, and Y viruses. The two-step(More)
In vitro shoot tips from PVS-infected potato breeding clones and cultivars were exposed to a constant temperature of 34 C and 8,100 lux light. Meristems were excised from heat-treated shoot tips after 3 to 7 weeks of heat therapy. Serological tests were performed on shoot tips derived from meristems excised from heat-treated shoot tips. Additional(More)