Genome-wide identification of MITE-derived microRNAs and their targets in bread wheat

Background Plant miRNAs are a class of small non-coding RNAs that can repress gene expression at the post-transcriptional level by targeting RNA degradation or promoting translational repression. There is increasing evidence that some miRNAs can derive from a group of non-autonomous class II transposable elements called Miniature Inverted-repeat Transposable Elements (MITEs). Results We used public small RNA and degradome libraries from Triticum aestivum to screen for microRNAs production and predict their cleavage target sites. In parallel, we also created a comprehensive wheat MITE database by identifying novel elements and compiling known ones. When comparing both data sets, we found high homology between MITEs and 14% of all the miRNAs production sites detected. Furthermore, we show that MITE-derived miRNAs have preference for targeting degradation sites with MITE insertions in the 3' UTR regions of the transcripts. Conclusions Our results revealed that MITE-derived miRNAs can underlay the origin of some miRNAs and potentially shape a regulatory gene network. Since MITEs are found in millions of insertions in the wheat genome and are closely linked to genic regions, this kind of regulatory network could have a significant impact on the post-transcriptional control of gene expression.

Automated summary

This study analyzed small RNA and degradome libraries from Triticum aestivum and found that MITEs (Miniature Inverted-repeat Transposable Elements) may be the origin of some miRNAs, and miRNAs derived from MITEs preferentially target degradation sites with MITE insertions in the 3' UTR regions of transcripts. This regulatory network could have a significant impact on the post-transcriptional control of gene expression.