Effects of the Ib-miR168-3p–IbKTN80 module on jasmonate biosynthesis in the systemic leaves of sweet potato after wounding

MicroRNAs (miRNAs) control their target genes by RNA cleavage or translation inhibition. The regulation of miRNA in the local leaves of plants after wounding has been studied, but its systemic effect is less understood. In this study, wounding-induced miR168-3p in the systemic leaves of sweet potato (Ipomoea batatas cv. Tainung 57) was analysed. Bioinformatics analysis indicated that the target gene of miR168-3p is IbKTN80, which encodes the katanin p80 subunit. The relationship between miR168-3p and IbKTN80 was confirmed by agroinfiltration with transient expression of primary miR168 and IbKTN80 transcript. Transgenic sweet potatoes with overexpressed or silenced miR168-3p further confirmed that IbKTN80 was the target gene of miR168-3p. Moreover, IbKTN80 is homologous to AtKTN80.2, and the expression of IbKTN80 could recover the functional defectiveness of AtKTN80.2 in Arabidopsis treated with abscisic acid. IbKTN80, similar to AtKTN80.2, regulated MYC2, which is involved in jasmonate signaling and biosynthesis. In conclusion, wounding induced the systemic generation of miR168-3p, which repressed the expression of IbKTN80. The miR168-3p-IbKTN80 module was involved in JA regulation and may participate in the signal transduction of systemic effects.