A Novel DCL2-Dependent Micro-Like RNA -PC-3p-92107_6 Affects Pathogenicity by Regulating the Expression of - in .

Dicer proteins are mainly responsible for generating small RNAs (sRNAs), which are involved in gene silencing in most eukaryotes. In previous research, two DCL proteins in , the pathogenic fungus causing apple tree canker, were found associated with both the pathogenicity and generation of sRNAs. In this study, the differential expression of small interfering RNAs (siRNAs) and miRNA-like RNAs (milRNAs) was analyzed based on the deep sequencing of the wild type and - mutant, respectively. Overall, the generation of 40 siRNAs and 18 milRNAs was evidently associated with - The target genes of milRNAs were then identified using degradome sequencing; according to the prediction results, most candidate targets are related to pathogenicity. Further, expression of -PC-3p-92107_6 was confirmed in the wild type but not in the - mutant. Moreover, the pathogenicity of -PC-3p-92107_6 deletion mutants (Δ-PC-3p-92107_6) and the over-expression transformants (-PC-3p-92107_6-OE) was significantly increased and decreased, respectively. Based on those degradome results, vacuolar protein sorting 10 (-) was identified as the target of -PC-3p-92107_6. Co-expression analysis in tobacco leaves further confirmed that -PC-3p-92107_6 could suppress the expression of -. Meanwhile, the expression levels of -PC-3p-92107_6 and - displayed divergent trends in Δ-PC-3p-92107_6 and -PC-3p-92107_6-OE, respectively. Perhaps most importantly, Δ- featured a significant reduction in pathogenicity. Taken together, our results indicate that a DCL2-dependent milRNA -PC-3p-92107_6 plays roles in pathogenicity by regulating the expression of -. This study lays a foundation for the comprehensive analysis of pathogenic mechanisms of and deepens our understanding of the generation and function of fungal sRNA.