HIGH-LEVEL OF RESISTANCE IN POTATO TO POTATO MOP-TOP VIRUS-INDUCED BYTRANSFORMATION 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 soi l infested with viruliferous Spongospora subterranea (the vector of PM TV). 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 o ne transgenic Pentland Marble tuber of 261 tested from four lines was infected. Spraing symptoms were not seen in any Saturna tubers, but le ss than 1% of transgenic Pentland Marble tubers developed symptoms com pared to 12% of those from control Pentland Marble plants.