P15 hairpin constructs and use

摘要

The present invention concerns a method of genetic modification of a TGB-3 wild type viral sequence for reducing or suppressing the possible deleterious effects of the agronomic properties of a transformed plant or plant cell by said TGB-3 viral sequence, comprising the following successive steps: submitting said sequence to point mutation(s) which allow the substitution of at least one amino-acid into a different amino-acid; selecting genetically modified TGB-3 wild type viral sequences having said point mutation(s) and which are not able to promote cell-to-cell movement of a mutant virus having a dysfunctional TGB-3 wild type viral sequence, when expressed in trans from a replicon; further selecting among said genetically modified TGB-3 viral sequences, the specifically genetically modified sequence which inhibits infection with a co-inoculated wild type virus when the mutant form was expressed from a replicon, and recovering said specifically genetically modified TGB-3 viral sequence. The invention further relates to genetically modified TGB-3 viral sequences suitable to induce gene silencing. In particular hairpin constructs based on such sequences proved highly efficient to induce a PTGS mechanism and degradation of the whole of RNA2 thereby. When plants are transformed accordingly the spread of the virus in the plant is significantly reduced or blocked.