High level of resistance in potato to potato mop-top virus induced by transformation with the coat protein gene

Transgenic plants of potato cvs Saturna and Pentland Marble expressing the potato mop-top virus (PMTV) coat protein (CP) gene were produced. Plants contained transgene RNA transcript and CP. In resistance tests made in a screenhouse, plants were grown in pots containing field soil infested with viruliferous Spongospora subterranea (the vector of PMTV). PMTV infection of the daughter tubers was determined by ELISA; 10% and 17%, respectively, of tubers from non-transformed control plants of Saturna and Pentland Marble became infected. However, tubers from six transgenic Saturna lines were immune to PMTV infection, and only one transgenic Pentland Marble tuber of 261 tested from four lines was infected. Spraing symptoms were not seen in any Saturna tubers, but less than 1% of transgenic Pentland Marble tubers developed symptoms compared to 12% of those from control Pentland Marble plants.