Transmission of tobacco rattle virus (TRV) via seed potatoes

Susceptibility of potato varieties for tobacco rattle virus (TRV) and sensitivity for spraing in potato tubers both depend on the interaction between cultivar and virus strain. Of the six potato cultivars investigated in this research, cultivar Santana was the most susceptible to TRV, the cultivars Roxy and Saturna were the least susceptible. In general, potato cultivars were most susceptible to the virus type transmitted by P. pachydermus and least for the virus type transmitted by T. primitivus. Potato cultivars showed a large difference in susceptibility for various TRV types. This was the most obvious for cultivar Wilja. Wilja showed high virus concentrations (susceptible) for a virus type transmitted by P. pachydermus but very low concentrations (resistant) for virus types transmitted by P. teres and T. primitivus. Cultivar Santana was the most sensitive for spraing, cultivar Wilja was the least sensitive. As Wilja is very susceptible to the virus strain transmitted by P. pachydermus, but is insensitive for spraing caused by this strain, this cultivar is called a "symptomless carrier" for this type of TRV. All six investigated potato cultivars can pass on TRV via seed potatoes to the next generation (secondary infection) but the degree of this virus transmission depended on potato cultivar, virus type and the interaction between cultivar and TRV and seems to be connected with the susceptibility for TRV. Transmission of the TRV type of P. pachydermus via seed potatoes was the highest in the cultivars Santana and (to a lesser degree) Santé and in cultivar Wilja. Even in the very sensitive cultivar Santana, TRV was passed on via seed potatoes. The prevailing theory that in sensitive potato cultivars TRV particles are immobilized in the necrotic 'spraing' tissue, therefore seems to be inaccurate. Since virus-vector combinations show specific interactions with cultivars, it is recommended to do potato variety research in several fields with different viruliferous trichodorid species.