The involvement of miR2111 in wounding response of sweet potato (Ipmoea batatas cv. Tainung 57)

Plant microRNAs (miRNAs), which are 20-24 nucleotides small non-coding RNAs, play crucial roles not only in the various developmental processes but also in the responses to biotic and abiotic stresses. One of the most severe stresses is wounding, which affects plant growth and development and causes food production lost. In this study, a wounding-reduced miRNA, miR2111, was identified in sweet potato (Impomoea batatas cv. Tainung 57). It was found that expression of miR2111 reduced after mechanical wounding. Furthermore, the target gene of miR2111 is IbFBK, which encodes the F-box/kelch repeat protein. Wounding can induce the expression of IbFBK, and IbFBK mRNA is cleaved in the region between 10th and 11th nucleotides of miR2111. In addition, wounding treatment in pre-miR2111 overexpressing transgenic sweet potato showed that IbFBK is downregulated. This results further indicated the existence of the relationship between miR2111 and IbFBK. IbFBK was predicted to be a component of E3 ligase SCF (SKP1-Cullin1-F-box) complex. Results of yeast two-hybried suggest that IbFBK, as a Kelch-type F-box protein, forms an SCF complex with IbSKP1, and binds to IbCNR8 for ubiquitin modification.