Co-infection of tomato brown rugose fruit virus and cucumber mosaic virus in tomato in Iran

During surveys conducted in several greenhouses in northwestern and southwestern Iran in the fall of ۲۰۲۱-۲۰۲۲, viral symptoms such as leaf mosaic, leaf deformation, and shoestring were observed in several tomato plants. Reverse transcription polymerase chain reaction (RT-PCR) was performed using specific primers to detect the tomato brown rugose fruit virus (ToBRFV). A ۴۵۸ base pair fragment corresponding to a part of the coat protein gene was amplified in all symptomatic samples. Sequence blast analysis and multiple alignment of the sequenced isolate with those of the isolates obtained from GenBank revealed ۹۹.۷۶% nucleotide sequence identity with existing GenBank isolates. Phylogenetic analysis grouped ToBRFV isolates into three clades, the Iranian isolate (Jol-F-۲۰۲۲) fell into clade II. The possibility of mixed infection in the samples with important viruses was investigated using universal orthotospovirus primers, pepper mild mottle virus (PMMoV), tomato mosaic virus (ToMV), and cucumber mosaic virus (CMV)-specific primers. In five samples, CMV-specific primers amplified a ۶۵۷-base pair fragment of the envelope protein gene, whereas no fragment was amplified with general primers for the orthotospovirus genus and specific primers for PMMoV, ToMV. Nucleotide blast (BLASTn) analysis revealed a nucleotide sequence identity around ۹۵.۱۳-۹۸.۸۵ between the Iranian CMV isolate and the corresponding sequences in the GenBank. Phylogenetic analysis based on the nucleotide sequences of the coat protein gene grouped the CMV isolates into three major groups, the Iranian isolate grouped with the Indian CMV isolates in the subgroup IB. Biological studies were performed by mechanical inoculation of an infected sample on Nicotiana rustica. The inoculated plants showed severe mosaic symptoms at ۱۵ days post inoculation (dpi), and infection by both viruses was confirmed through RT-PCR using specific primers. This study presents the first report of mixed infection of tomato plants with ToBRFV and CMV in Iran.

کلیدواژه ها:

Phylogentic Analysis ، Tomato ، Emerging threat ، Subgroup IB ، Mixed infection