The first report of the occurrence of alfalfa mosaic virus on Tropaeolum majus and Rudbeckia hirta in Iran

Tropaeolum majus (garden nasturtium) and Rudbeckia hirta are common ornamental plants that can be susceptible to plant virus infections, leading to symptoms that adversely affect their ornamental appeal and commercial production. In this research, severe leaf chlorosis was observed on T. majus and R. hirta plants in green spaces in Shiraz and Bushehr, Iran (2023). Total RNA was extracted from five symptomatic leaf samples of each species, as well as one asymptomatic sample as a negative control. RT-PCR with alfalfa mosaic virus (AMV)-specific primers successfully amplified the expected 780 bp fragment in all symptomatic samples, but not in the asymptomatic control. Nucleotide sequencing confirmed the 780 bp size of the amplicon, and analysis revealed that the AMV isolates infecting T. majus (IR-GN01-Shiraz and IR-GN02-Bushehr) were most similar to an Iranian AMV isolate (Acc. No. MW_014931.1), while those infecting R. hirta (IR-AN04-Shiraz and  IR-AN03-Bushehr) were the most similar to Chinese AMV isolates. This study is the first report of AMV infecting T. majus and R. hirta in Iran, a noteworthy finding, considering the extensive cultivation of these ornamental plants and the potential impact of AMV on their visual and economic value.