5 Small RNAs in Fungi

The RNAi Machinery in the Fungus Fusarium fujikuroi Is Not Very Active in Synthetic Medium and Is Related to Transposable Elements

“…Among them, microRNAs (miRNAs) stand out as a large family of sRNAs with conserved regulatory functions in eukaryotes [ 1 ], usually involved in the suppression of gene expression through sequence-specific messenger RNA degradation, translational repression, or transcriptional inhibition [ 2 ]. RNA co-suppression was initially described in plants [ 3 ], but fungi have played an important role since the pioneering discovery of quelling in Neurospora crassa [ 4 ], and the subsequent finding of other RNAi mechanisms mediated by sRNAs in this and other fungi [ 5 , 6 ].…”

“…Fungal RNAi-related sRNAs can be divided into two main subclasses according to their biological role: protective sRNAs and regulatory sRNAs [ 6 ]. Those in the first group are involved in genome defense, which is probably the original evolutionary function of RNAi systems.…”

“…Their discovery in fungi started with miRNAs and other regulatory sRNAs in N. crassa [ 17 ] and Mucor circinelloides [ 18 ]. Those of N. crassa , termed miRNA-like small RNAs (milRNAs), are subdivided into four classes depending on the RNAi components required for their biogenesis [ 6 ] and are derived from single-strand RNA precursors that form a typical hairpin structure. Its dsRNA region is processed to generate two complementary sRNAs; one of them is predominantly conserved, while the other is degraded.…”