XRN1‐associated long non‐coding RNAs may contribute to fungal virulence and sexual development in entomopathogenic fungus Cordyceps militaris

Abstract

BACKGROUND Numerous long non‐coding RNAs (lncRNAs) identified and characterized in mammals, plants, and fungi have been found to play critical regulatory roles in biological processes. However, little is known about the role of lncRNAs in insect pathogenic fungi. RESULTS By profiling the transcriptomes of sexual and asexual development in the insect‐pathogenic fungus Cordyceps militaris, 4140 lncRNAs were identified and found to be dynamically expressed during fungal development. The lncRNAs had shorter transcript lengths and lower numbers of exons compared to protein‐coding genes. The expressed target genes (neighboring and cis‐regulated) of various expressed lncRNAs were predicted, and these genes showed significant enrichment in energy metabolism and signaling pathways, such as ‘Glycolysis/Gluconeogenesis’ and “MAPK signaling pathway”. To better understand how lncRNAs function in the fungus, xrn1, the final gene of the NMD pathway, which determines the fate of lncRNAs, was disrupted. The Δxrn1 deletion mutant displayed significant (P < 0.05) attenuation of virulence and a lower growth rate in C. militaris. Quantitative RT‐PCR results revealed 10 lncRNAs with significantly higher expression, while 8 of these 10 lncRNA target genes (virulence‐ and sexual development‐related) showed significantly lower expression in Δxrn1 compared to in the wild‐type, suggesting that lncRNA expression regulates fungal virulence and sexual development by affecting gene expression. CONCLUSION These findings suggest that lncRNAs in C. militaris play important roles in the fungal infection progress and fruiting body production, providing a broad repertoire and resource for further studies of lncRNAs. © 2019 Society of Chemical Industry

Genome-Wide Identification and Functional Prediction of Long Non-coding RNAs Involved in the Heat Stress Response in Metarhizium robertsii

“…Deletion of the lncRNA gene (Gene_ID: LXLOC_012667, Transcript_ID: TCONS_00017175, referred to herein as mrLncRNA1 ) was performed by introducing a glufosinate ammonium (bar) resistance marker in the lncRNA gene of interest by Agrobacterium -mediated fungal transformation as described previously (Chacko et al, 2015; Wang y. et al, 2019; Wang Z.X. et al, 2019).…”

“…For complementation, the mrLncRNA1 transcript together with its promoter region was amplified by PCR, and the product was digested with Spe I and inserted into the binary vector pDHt-SK- ben (conferring resistance to benomyl) for ectopic integration into Δ mrLncRNA1 to obtain the complemented strain (Comp). The positive transformants were confirmed by PCR and RT-PCR as previously described (Wang y. et al, 2019; Wang Z.X. et al, 2019) (Supplementary Figures S1B,C).…”

“…In recent years, the number of lncRNAs identified in yeast has increased rapidly (Till et al, 2018a); in particular, an increasing number of stress-responsive lncRNAs have been found in yeast (Sun et al, 2019). Furthermore, several recent studies have examined the lncRNA-associated growth and development of filamentous fungi such as Neurospora crassa (Arthanari et al, 2014; Cemel et al, 2017), Fusarium graminearum (Kim et al, 2018), Trichoderma reesei (Till et al, 2018b), and Cordyceps militaris (Wang y. et al, 2019). However, there are only a few comprehensive surveys regarding the lncRNAs involved in the response to heat stress in filamentous fungi, including M. robertsii .…”

Long noncoding RNAs are potentially involved in the degeneration of virulence in an aphid-obligate pathogen, Conidiobolus obscurus (Entomophthoromycotina)

“…Recently, long noncoding RNAs (lncRNAs) have been found to be related to the virulence of insect-pathogenic fungi [ 6 ]. lncRNAs are loosely defined as noncoding transcripts that are longer than 200 nucleotides and are primarily transcribed by RNA polymerase II, while lacking an open reading frame (ORF) [ 7 ].…”

“…Their transcriptional regulation could act in cis or in trans modes, while either negatively or positively controlling protein-coding gene expression [ 7 ]. Multiple biological processes, including disease resistance, sexual development, stress response, and metabolite biosynthesis, were found to be related to lncRNA regulation [ 6 , 8 , 9 ]. Thus, lncRNAs may play a role in virulence attenuation during long-term serial culture of mycopathogens.…”