Development of a Real-Time RT-PCR SYBR Green Assay for Tomato ring spot virus in Grape.

Grapevines infected with Tomato ring spot virus (ToRSV) pose an economic risk for growers in the northeastern United States. This study describes a one-step real-time reverse-transcription polymerase chain reaction (RT-PCR) SYBR Green assay for detecting ToRSV in grapevines. Two newly designed primer pairs based on the ToRSV coat protein gene sequence were evaluated for specificity and optimized for a SYBR Green assay. The primer pair ToRSV1f/1r yielded a 130-bp product with strong primer-dimer products, whereas the primer pair ToRSV2f/2r yielded a 330-bp product with weak primer dimer products. Real-time RT-PCR detected ToRSV in more naturally infected grapevines maintained in the greenhouse than did enzyme-linked immunosorbent assay. The nucleotide sequences of the fragments amplified from grapevine growing in Pennsylvania using real-time PCR were divergent from previously published sequences.