UV-B responsive microRNA genes in Arabidopsis thaliana

MicroRNAs are small, non-coding RNAs that play critical roles in post-transcriptional gene regulation. In plants, mature microRNAs pair with complementary sites on mRNAs and subse-quently lead to cleavage and degradation of the mRNAs. Many microRNAs target mRNAs that encode transcription factors, therefore, they reg-ulate the expression of many down-stream genes. In this study, we carry out a survey of Arabidop-sis microRNA genes in response to UV-B radia-tion, an important adverse abiotic stress. We de-velop a novel computational approach to identify microRNA genes induced by UV-B radiation and characterize their functions in regulating gene ex-pression. We report that in A. thaliana 21 mi-croRNA genes in 11 microRNA families are up-regulated under UVB stress condition. We also discuss putative transcriptional down-regulation pathways triggered by the induction of these mi-croRNA genes. Moreover, our approach can be directly applied to miRNAs responding to other abiotic and biotic stresses and extended to miR-NAs in other plants and metazoans. ∗These authors contributed equally to this research