Solanum berthaultii P.I. 265858; a possible source of protection against all strains of PVX

Summary A clone ofSolanum berthaultii P.I. 265858 was not systemically infected when manually inoculated with isolates of PVX groups 1 to 3 but developed top-necrosis when grafted-inoculated, demonstrating it is hypersensitive. Plants sap- or graft-inoculated with an isolated of PVX group 4 or with PVX_HB (a recently-discovered strain overcoming all reported sources of resistance to PVX) were infected systematically. The plants were extremely sensitive to these isolates, young leaves becoming necrotic and the plant dying within a few weeks and, whilst still alive, plants contained little virus and were a poor source of infection. These characteristics suggest that this clone could provide a means of breeding cultivars that would be protected against all known strains of PVX.