MiR393-targeted TIR1-like (F-box) gene in response to inoculation to R. Solani in Zea mays

MicroRNAs (miRNAs) are a class of small non-coding RNAs that negatively regulate special target mRNAs at the post-transcriptional level by directing target mRNA cleavage or translational inhibition. Plant miRNAs regulate gene expression mainly by guiding cleavage of target mRNAs and subsequently play important roles in diverse developmental processes, nutrient homeostasis and responses to biotic and abiotic stresses. MiRNA393 plays important and diverse roles in defense against bacterial pathogens by negatively targeting transport inhibitor response 1 (TIR1) in plant development. It will be essential for understanding complex feedback regulations in the development pathway by unraveling the miR393 network in a temporal and spatial manner. Here, we report that Zma-miR393b down-regulates its putative target TIR1-like (F-box) gene by guiding the cleavage of their mRNAs in development of leaf sheaths in response to R. Solani infection, Zma-miR393b and its putative target gene TIR1 were confirmed through Q-PCR and the spatial expression of Zma-miR393b was further analyzed by in situ hybrid- ization. These findings suggested that, as a negative feed- back regulation of TIR1-like (F-box) gene, Zma-miR393b plays an important role in defense against R. Solani infection.