Biological and Molecular Characterization of the Cucumber Mosaic Virus Infecting Purple Coneflowers in China

Purple coneflower (Echinacea purpurea L.), which is a perennial herbaceous plant belonging to the Asteraceae family, is extensively cultivated because of its medicinal applications. However, in Hohhot, Inner Mongolia, China, purple coneflowers in the field exhibited symptoms such as mottle, mosaic, and crinkle. This study aimed to explore the biological and molecular characteristics of the cucumber mosaic virus (CMV) infecting the purple coneflowers in China. We observed isometric particles approximately 30 nm in diameter in the symptomatic leaf specimens. Infection with the CMV was confirmed via high-throughput sequencing and RT-PCR validation. Mechanical inoculation assays demonstrated that the CMV-SGJ isolate could infect both Nicotiana benthamiana and Nicotiana tabacum. Three viral genomic components were identified: RNA1 with 3321 nucleotides, RNA2 with 3048 nucleotides, and RNA3 with 2209 nucleotides. Phylogenetic analysis revealed that the CMV-SGJ isolate clustered into phylogenetic subgroup IA, exhibiting a nucleotide identity of 92.2-95% with subgroup IA CMV isolates in GenBank. This report is the first documentation of the complete genome of the CMV infecting purple flowers in China.