Distribution of tobacco rattle virus in tubers of resistant and susceptible potatoes and systemic movement of virus into daughter plants

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 vir us (TRV) and vector nematodes, Paratrichodorus allius Jen. (Sid.). Tubers f rom these field plots were cut and examined for corky ringspot (CRS) sympto ms, Reverse transcription-polymerase chain reaction (RT-PCR) for TRV was co nducted on tissue samples from symptomatic and asymptomatic tubers. Sixty-f ive percent of the symptomatic and 42% of the asymptomatic tissue samples f rom CRS symptomatic tubers contained detectable TRV. Approximately 2% of pl ants grown from either symptomatic or asymptomatic tubers contained TRV whe n tested by ELISA, whereas 20% and 12% of plants grown from symptomatic and asymptomatic tubers, respectively, were positive for TRV by RT-PCR. These results suggest that RT-PCR is a more sensitive assay for detection of TRV. Systemic infections by TRV were detected more often in foliage of CRS-susc eptible genotypes. Daughter tubers exhibiting symptoms of CRS, and which co ntained RT-PCR-detectable TRV, were produced on plants of three genotypes, including one from an asymptomatic parent tuber.