Adaptive regulation of miRNAs/milRNAs in tissue-specific interaction between apple and .

In plant-pathogen interactions, pathogens display tissue specificity, infecting and causing disease in particular tissues. However, the involvement of microRNAs/microRNA-like RNAs (miRNAs/milRNAs) in tissue-specific regulation during plant-pathogen interactions remains largely unexplored. This study investigates the differential expression of miRNAs/milRNAs, as well as their corresponding target genes, in interactions between () and different apple tissues. The results demonstrated that both apple miRNAs and milRNAs exhibited distinct expression profiles when infected bark and leaves, with functionally diverse corresponding target genes. Furthermore, one apple miRNA (Mdo-miR482a) and one milRNA (Vm-milR57) were identified as exhibiting tissue-specific expression in interactions between and apple bark or leaves. Mdo-miR482a was exclusively up-regulated in response to infection in bark and target a nucleotide-binding leucine-rich repeat (NLR) gene of apple. When Mdo-miR482a was transiently over-expressed or silenced, the resistance was significantly reduced or improved. Similarly, transient expression of the NLR gene also showed an increase in resistance. Vm-milR57 could target two essential pathogenicity-related genes of . During infection in bark, the expression of Vm-milR57 was down-regulated to enhance the expression of the corresponding target gene to improve the pathogenicity. The study is the first to reveal tissue-specific characteristics of apple miRNAs and milRNAs in interactions between and different apple tissues, providing new insights into adaptive regulation in tissue-specific interactions between plants and fungi.