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.