Regulation of rice root development by a retrotransposon acting as a microRNA sponge

Transposable elements are known to affect their neighboring genes, but they were so far unknown to affect the function of distant genes. Cho and Paszkowski observed a high level of transposon transcription expressed in rice. A transposon with root specific expression, MIKKI, was found to contain an imperfect binding site for miRNA171, which in turn is known to target mRNAs of SCARECROW-like (SCL) transcription factors. Transgenic lines overexpressing MIKKI showed higher levels of SCL expression, resulting in abnormal flower development and sterility. On the other hand, lines where the recognition site for miRNA171 in  MIKKI was mutated showed reduced SCL expression and reduced root length. This is the first study to show that TE-derived RNA acts as a molecular sponge for miRNA and affects plant development. (Summary by Magdalena Julkowska) eLIFE 10.7554/eLife.30038

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