In this study, a novel double-stranded RNA (dsRNA) mycovirus, named Cordyceps chanhua alternavirus 1 (CcAV1), was detected in the entomogenous fungus Cordyceps chanhua from China. The complete genome of CcAV1 contained three dsRNA genome segments, dsRNA 1 (3,512 bp), dsRNA 2 (2,655 bp), and dsRNA 3 (2,415 bp). All the three dsRNAs possess a single open reading frame (ORF). DsRNA 1 with 3,512 bp long encoded a putative RNA-dependent RNA polymerase (RdRp), while dsRNA 2 with 2,655 bp long and dsRNA 3 with 2,415 bp long encoded a hypothetical protein 1 (HP 1) and a hypothetical protein 2 (HP 2), respectively. The RdRp, HP 1 and HP 2 sequences had the highest identity of 66.99%, 49.30% and 56.91%, respectively, to those of Aspergillus foetidus dsRNA mycovirus. A maximum-likelihood phylogenetic tree from RdRp sequence revealed that CcAV1 was placed in the clade of the proposed family "Alternaviridae". Hence, we proposed that Cordyceps chanhua alternavirus 1 is a novel member of the proposed "Alternaviridae".

No abstract

Cicada flower, scientifically named Cordyceps chanhua, is an important and well-known Chinese cordycipitoid medicinal mushroom. Although most mycoviruses seem to induce latent infections, some mycoviruses cause host effects. However, the effects of mycovirus on the fungal development and stress tolerance of C. chanhua remain unknown. In this study, we report a novel mycovirus designated Cordyceps chanhua partitivirus 1 (CchPV1) from C. chanhua isolate RCEF5997. The CchPV1 genome comprises dsRNA 1 and dsRNA 2, 1784 and 1563 bp in length, respectively. Phylogenetic analysis using the aa sequences of RdRp revealed that CchPV1 grouped with members of the genus Gammapartitivirus in the family Partitiviridae. We further co-cultivated on PDA donor strain RCEF5997 and recipient C. chanhua strain RCEF5833 (Vf) for 7 days, and we successfully obtained an isogenic line of strain RCEF5833 with CchPV1 (Vi) through single-spore isolation, along with ISSR marker and dsRNA extraction. The biological comparison revealed that CchPV1 infection slows the growth rate of the host, but increases the conidiation and formation of fruiting bodies of the host. Furthermore, the assessment of fungal tolerance demonstrated that CchPV1 weakens the multi-stress tolerance of the host. Thus, CchPV1 infection cause changes in fungal development and multi-stress tolerance of the host C. chanhua. The findings of this study elucidate the effects of gammapartitivirus on host entomogenous fungi and provide a novel strategy for producing high-quality fruiting bodies of C. chanhua.

No abstract

In this study, a novel double-stranded RNA (dsRNA) mycovirus, named Cordyceps chanhua alternavirus 1 (CcAV1), was detected in the entomogenous fungus Cordyceps chanhua from China. The complete genome of CcAV1 contained three dsRNA genome segments, dsRNA 1 (3,512 bp), dsRNA 2 (2,655 bp), and dsRNA 3 (2,415 bp). All the three dsRNAs possess a single open reading frame (ORF). DsRNA 1 with 3,512 bp long encoded a putative RNA-dependent RNA polymerase (RdRp), while dsRNA 2 with 2,655 bp long and dsRNA 3 with 2,415 bp long encoded a hypothetical protein 1 (HP 1) and a hypothetical protein 2 (HP 2), respectively. The RdRp, HP 1 and HP 2 sequences had the highest identity of 66.99%, 49.30% and 56.91%, respectively, to those of Aspergillus foetidus dsRNA mycovirus. A maximum-likelihood phylogenetic tree from RdRp sequence revealed that CcAV1 was placed in the clade of the proposed family “Alternaviridae”. Hence, we proposed that Cordyceps chanhua alternavirus 1 is a novel member of the proposed “Alternaviridae”.