| abstract |
Disclosed are DNA constructs ('amplicons' TM) comprising a promoter operably linked to DNA which can be transcribed in a plant cell to an RNA transcript, which RNA transcript includes plant virus sequence (e.g. derived from potato virus X) which confers on the RNA transcript the ability to replicate in the cytoplasm of the plant cell. The constructs may lack portions of the viral genome not required for such replication (e.g. coat proteins) but preferably include targeting sequence which is capable of down-regulating (for instance gene silencing) expression of one or more target genes, which may be endogenous plant genes, transgenes, or pathogen genes. Also disclosed are corresponding vectors, host cells, plants (particularly having modified and/or silenced genes or being pathogen resistant) and plant products, plus also methods of producing and using these materials. |