Mno‐miR164a and MnNAC100 regulate the resistance of mulberry to Botrytis cinerea

Abstract Although microRNAs (miRNAs) regulate the defense response of a variety of plant species against a variety of pathogenic fungi, the involvement of miRNAs in mulberry's defense against Botrytis cinerea has not yet been documented. In this study, we identified responsive B. cinerea miRNA mno‐miR164a in mulberry trees. After infection with B. cinerea , the expression of mno‐miR164a was reduced, which was fully correlated with the upregulation of its target gene, MnNAC100 , responsible for encoding a transcription factor. By using transient infiltration/VIGS mulberry that overexpressed mno‐miR164a or knocked‐down MnNAC100 , our study revealed a substantial enhancement in mulberry's resistance to B. cinerea when mno‐miR164a was overexpressed or MnNAC100 expression was suppressed. This enhancement was accompanied by increased catalase (CAT) activity and reduced malondialdehyde (MDA) content. In addition, mno‐miR164a‐mediated inhibition of MnNAC100 enhanced the expression of a cluster of defense‐related genes in transgenic plants upon exposure to B. cinerea . Meanwhile, MnNAC100 acts as a transcriptional repressor, directly suppressing the expression of MnPDF1.2 . Our study indicated that the mno‐miR164a‐ MnNAC100 regulatory module manipulates the defense response of mulberry to B. cinerea infection. This discovery has great potential in breeding of resistant varieties and disease control.