الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 152 |  |  |
| | | from | 152 | | |
Abstract
Mycoviruses are widespread in members of all major groups of fungi. Most mycoviruses seem to be associated with asymptomatic persistent infections of their hosts. However, there are several important exceptions. Some mycoviruses mediate phenotypic debilitation in their hosts; they have been investigated for their use as biocontrol agents against plant pathogenic fungi. The current study was designed to reveal the prevalence of mycoviruses in soil fungi from Damietta governorate. Pure cultures of 47 fungal isolates from Damietta governorate, Egypt were obtained using traditional culturing techniques. All isolates were identified based on their morphological characteristics. Isolates were screened for the presence of RNA mycoviruses using dsRNA purification based on the selective binding of dsRNAs to CF11 cellulose in the presence of 16.5% ethanol and electrophoresis. Isolate NDC1 was associated with an RNA mycovirus with a non-segmented genome of approximately 3 kbp. Molecular identification revealed that this isolate belongs to Nigrospora oryzae (accession number OQ299130). Sequencing of the dsRNA segment from isolate NDC1 using Illumina sequencing revealed that it is 2858 nts long and comprises two ORFs with the potential to encode two viral proteins. ORF1 is 525 nts long and encodes a 174 aa long hypothetical protein with an estimated molecular mass of 19.24 kDa. ORF2 is 2184 nts long and codes for a 727 aa long protein with an estimated molecular mass of 82.84 kDa. The RdRp contains the aa conserved motifs of RdRp proteins, including the GDD region, which is highly conserved in motif C. NoNRV1-NDC1 encoded proteins share identities with other isolates of the same virus and with other unassigned closely related mycoviruses. The 5´ and 3´ terminal sequences of NoNRV1-NDC1 (+) RNA could form stem-loop secondary structures with ∆G values of -4.8 and -18.6 kcal/mole, respectively. Phylogenetic analysis confirmed the previous findings that NoNRV1-NDC1 is related to a group of yet to be assigned RNA mycoviruses.