Distribution and genetic diversity analysis of fig mosaic virus in Kermanshah Province, Iran

Abstract

Fig mosaic disease (FMD) poses a significant threat to fig (Ficus carica) trees globally. Fig mosaic virus (Emaravirus fici, Family Fimoviridae) is one of the main causes involved in FMD. E. fici has been reported in many countries, including Iran. This research investigated the genetic diversity and distribution of this virus in Kermanshah Province, the third fig-producing region in Iran. In 2021 and 2022, 128 samples, mainly displaying FMD symptoms, were collected from fig trees across nine counties. Using DAS-ELISA with polyclonal antibodies, 86 samples tested positive for fig mosaic virus. The 2-year-old healthy fig saplings grafted with scions from infected trees exhibited mosaic symptoms and tested positive for the virus in DAS-ELISA. Reverse transcription-polymerase chain reaction (RT-PCR) by RdRp-specific primers (E5-s and E5-a) also amplified a DNA fragment with the expected size of about 302 bp from the ELISA-positive samples. Five of the 12 symptomless samples showed positive results in both DAS-ELISA and RT-PCR. This indicates that the absence of symptoms in propagation sources does not imply that they are virus-free. Nucleotide sequences of RT-PCR products confirmed the fig mosaic virus infection. BLAST analysis of 20 samples (GenBank accession numbers OQ552535 to OQ552554) revealed that 19 sequences show high nucleotide identity (93.4%–96.8%) with an isolate from Lorestan Province, Iran (GenBank accession number KT732024). Notably, isolate FM203 showed distinct genetic divergence (86.6%–90.2% nucleotide identity) and shared similarities with some other Iranian isolates, including those from Kermanshah and Mazandaran provinces. Phylogenetic analysis grouped most isolates with the Lorestan isolate, while FM203 was placed in a separate cluster. This study highlighted the widespread presence of fig mosaic virus in Kermanshah Province, emphasizing varying infection rates across different counties, with Dalahoo County (Rijab) showing the highest prevalence.