Detection and phylogenetic analysis of saffron latent virus in saffron fields of South Khorasan and Razavi provinces

The Saffron Latent Virus (SaLV) is new species in the Potyvirus genus, which has been recently characterized from Iran. Even though most of the symptoms on infected plants remain hidden, it causes considerable damage to saffron fields. There is no data available on the phylogenetic relationship among different strains of this virus based on its coat protein, despite its high incidence and economic significance. To address this, we collected 152 samples of saffron leaves, flowers, and corms from fields in South Khorasan and Razavi Khorasan provinces, both with and without symptoms like stunting, yellowing, and twisting. After extracting RNA, the presence of SaLV was examined using reverse transcription-polymerase chain reaction (RT-PCR) with specific primers targeting the coat protein. The findings revealed that 92 out of 152 samples (60%) were infected with the virus. Subsequently, seven representative samples, each from a selected region were sequenced. Phylogenetic analysis using MEGAX software showed that the virus strains formed two distinct groups, and the strains studied were placed in the second group. Interestingly, strains from the same geographical region and product were distributed among different groups, suggesting that geographical separation and host type did not significantly impact the viral diversity. This study is the first in detecting of SaLV in saffron flowers and corms and pinpointing the diversity of its new strains based on the coat protein in Iran.