METHODS AND COMPOSITIONS FOR GENE SILENCING

摘要

Methods and compositions are provided for reducing the level of expression of a target polynucleotide in an organism. The methods and compositions selectively silence the target polynucleotide through the expression of a chimeric polynucleotide comprising the target for a sRNA (the trigger sequence) operably linked to a sequence corresponding to all or part of the gene or genes to be silenced. In this manner, the final target of silencing is an endogenous gene in the organism in which the chimeric polynucleotide is expressed. In a further embodiment, the miRNA target is that of a heterologous miRNA or siRNA, the latter of which is coexpressed in the cells at the appropriate developmental stage to provide silencing of the final target when and where desired. In a further embodiment, the final target may be a gene in a second organism, such as a plant pest, that feeds upon the organism containing the chimeric gene or genes. Compositions further comprise vectors, seeds, grain, cells, and organisms, including plants and plant cells, comprising the chimeric polynucleotide of the invention.