Tomato spotted wilt virus on potato in eastern North Carolina

Leaf, stem, and tuber samples collected from diseased potato plants exhibiting tospovirus-like symptoms in eastern North Carolina (NC) were assayed for the presence of Tomato spotted wilt virus (TSWV) by serology (ImmunoStrips) and reverse transcription-polymerase chain reaction (RT-PCR) methods. All symptomatic samples tested positive for TSWV with serology and RT-PCR. Mechanical inoculation of the indicator host Nicotiana benthamiana with symptomatic leaf, stem, and tuber tissue resulted in plants with symptoms of systemic virus infection. The presence of TSWV in infected tissue of N. benthamiana was confirmed with serology, RT-PCR, and sequence analysis of the nucleocapsid (N) protein gene. Phylogenetic analysis of the predicted N protein of three isolates of TSWV from potato in NC and 11 isolates obtained from peanut, pepper, and tomato in Georgia and NC suggested that the isolates were related. One isolate of TSWV from potato in NC was selected for vector transmission tests, and the virus was transmitted to potato with tobacco thrips (Frankliniella fusca), but no vertical transmission from infected seed tubers to actively developing potato sprouts, stems or leaves was observed. This is the first documentation of the occurrence, isolation and characterization of TSWV from field-grown potato in North America.