Methods controlling gene expression

The present invention is in the field of genetics， especially plant genetics， and provides agents capable of controlling gene expression. The present invention specifically provides sequences of naturally occurring， tissue-specifically expressed microRNAs. The invention further provides for transgenic expression constructs comprising sequences encoding such microRNAs. By incorporation of the microRNA encoding sequence the expression from the expression construct is specifically silenced in the tissue where the naturally occurring microRNA is naturally expressed. Thereby the expression profile resulting from the promoter is modulated and leakiness is reduced. The invention further provides for a method for modulating transgenic expression by incorporating sequences encoding the microRNAs into transgenic expression constructs. The compositions and methods of the invention can be used to enhance performance of agricultural relevant crops and for therapy， prophylaxis， research and diagnostics in diseases and disorders， which afflict mammalian species.