Coat protein RNAs-mediated protection against Andean potato mottle virus in transgenic tobacco

The expression of translatable sequences of either one of the two Andean po tato mottle virus (APMoV) coat protein (CP) genes (CP22 and CP42) and of th e nontranslatable sequence of CP42 in transgenic tobacco provided protectio n against APMoV. Resistance was mediated by CP transgene RNAs rather than t he protein, as an inverse correlation between resistance and the accumulati on levels of CPs transgene mRNAs was observed. These data indicated that a post-transcriptional gene silencing (PTGS) mechanism is likely involved in the APMoV CP RNA-mediated protection. Moreover, the HindIII-AccI restrictio n pattern of the CP22 transgene was different in susceptible and resistant transgenic plants, suggesting the involvement of methylation in PTGS. South ern blot experiments also revealed that CPs transgene insertion loci and or ganisation in the plant genome may play a role in determining the degree of protection. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.