Dicer-Like Proteins Regulate Sexual Development via the Biogenesis of Perithecium-Specific MicroRNAs in a Plant Pathogenic Fungus Fusarium graminearum

Ascospores act as the primary inoculum of , which causes the destructive disease Fusarium head blight (FHB), or scab. MicroRNAs (miRNAs) have been reported in the vegetative stage, and is involved in microRNA-like RNA (milRNA) biogenesis but has no major impact on vegetative growth, abiotic stress or pathogenesis. In the present study, we found that ascospore discharge was decreased in the deletion mutant, and completely blocked in the double-deletion mutant of and . Besides, more immature asci were observed in the double-deletion mutant. Interestingly, the up-regulated differentially expressed genes (DEGs) common to and were related to ion transmembrane transporter and membrane components. The combination of small RNA and transcriptome sequencing with bioinformatics analysis predicted 143 novel milRNAs in wild-type perithecia, and 138 of these milRNAs partly or absolutely depended on , while only 5 novel milRNAs were still obtained in the and double-deletion mutant. Furthermore, 117 potential target genes were predicted. Overall, and genes were partly functionally redundant in ascospore discharge and perithecium-specific milRNA generation in , and these perithecium-specific milRNAs play potential roles in sexual development.