Resistance to potato virus Y and potato virus X in Solanurn brevidens

Although Solanum brevidens could be infected with potato virus X (PVX), potato virus Y0 (PVY0) and PVYN, no symptoms of infection were apparent and tests by double antibody sandwich ELISA, electron microscopy and sap transmission to local lesion test plants indicated that the titres of PVX were less than a tenth of those of PVY0 and PVYN were less than a hundredth of those in infected plants of PDH40, a susceptible dihaploid clone of S. tuberosum cv. Pentland Crown. Furthermore, PVY0‐ and PVYN‐ infected leaves of S. brevidens were a poor source of inoculum in aphid transmission tests. The possibility of a common mechanism and genetic basis of resistance to PVY, PVX and potato leaf roll virus in S. brevidens is discussed