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چکیده
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Strawberry (Fragaria × ananassa Duch.) is grown primarily in the west (Kurdistan Province) and north (Golestan, Mazandaran, and Guilan) of Iran on approximately 2,650 and 1,650 ha, respectively. In the past several years, viral diseases have emerged as a serious threat to strawberry production in the country (Hajizadeh et al. 2022; Zandan et al. 2022). To determine which viruses are present, a sample, KM (Fragaria × ananassa var. Kurdistan), with chlorosis and leaf and fruit deformation symptoms was sequenced using the MinION platform, as described by Liefting et al. (2021). A total of 50,600 raw reads (mean length of 548 nt) were analyzed using VirFind (Ho and Tzanetakis 2014), which identified partial genomic sequences of multiple viruses, including strawberry pallidosis-associated virus (Crinivirus, MN747002), strawberry mottle virus (Stramovirus, MZ328097), strawberry crinkle virus (Cytorhabdovirus, MH129615), strawberry crinivirus 4 (MZ326667), and strawberry virus 3 (StrV-3). StrV-3 has only been reported in the United States so far (Medberry et al. 2023). It belongs to the family Rhabdoviridae and is a putative member of a new genus in the family. To obtain more information on the Iranian StrV-3 isolate, the sample KM was also subjected to Illumina sequencing, as previously described (Villamor et al. 2022). A total of 887,477 reads were obtained after removing the reads mapped to the host genome. There were 16,986 StrV-3 reads that were de novo assembled in a contig of 14,406 nt, representing 99.8% of the virus genome (GenBank accession no. OR365282) and having 98.3% nt sequence identity to the type isolate “Fragaria 7” (GenBank accession no. MW503935). The presence of the virus was further verified using reverse transcription polymerase chain reaction (RT-PCR) with the primers StrV-3 L1352F (5′-CTGTGCCCACAGGTATGAACATAGC-3′) and StrV-3 L2148R (5′-TAGGACCTGGTTGTCCCCTCC-3′) (Medberry et al. 2023), yielding a 796-bp fragment, which was sequenced bidirectionally. To determine the virus presence in Iran, a small field survey was conducted at two main production areas. Among the 45 strawberries sampled (30 samples from western Iran and 15 samples from northern Iran), two symptomatic plants (K and SS2) from western Iran tested positive for StrV-3 as well as other strawberry viruses (data not shown). The RT-PCR fragment obtained from the StrV-3 isolate K was cloned and sequenced directionally. The obtained sequence was submitted to GenBank under accession number OR365281 which shared 99.1 and 98.0% nt identity with the StrV-3 isolate KM and the isolate Fragaria 7, respectively. To the best of our knowledge, this is the first report of StrV-3 outside of the United States. The low incidence of StrV-3 suggests that this virus is not widespread in Iran. Routine monitoring and detection of StrV-3 are required to prevent further spread of the virus in the country. Even though there is limited knowledge of StrV-3 impact on single infections, the presence of an additional virus infecting the crop is of concern because in the majority of cases, symptom severity increases with the number of viruses infecting the plant (Tzanetakis and Martin 2017).
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